The Converter`s Guide to the Galaxy and EV Conversions

The Converter’s Guide to
the Galaxy and EV
Conversions
By
Richard W. Marks
President
EnVironmental Transportation
Solutions, LLC
rev. December 15, 2008
Rev. April 24, 2015
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Table of Contents
Introduction:.................................................................................................................................... 3
Chapter 1: The Art of Designing a “Real” Vehicle or an EV Conversion Vehicle ........................ 8
Chapter 2: High Voltage Safety and Overall Vehicle Safety/Reliability/Durability ................... 18
Chapter 3: EV Batteries for Conversion Vehicles ........................................................................ 24
Chapter 4: EV Chargers for Conversion Vehicles ........................................................................ 37
Chapter 5: Drive Systems for EV Conversions ............................................................................ 41
Chapter 6: Automotive Electrical Systems for EV Conversions .................................................. 59
Chapter 7: Original ICE vehicle and its systems .......................................................................... 66
Chapter 8: Conversion Process .................................................................................................... 73
Chapter 9: Example of an “OEM-grade” conversion ................................................................... 77
Chapter 10: Conclusions about Conversions .............................................................................. 108
Chapter 11: Bibliography............................................................................................................ 110
Chapter 12: Appendices .............................................................................................................. 112
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Introduction:
Welcome to the Converter’s Guide to the Galaxy and EV Conversions. Why
the Galaxy? Well, EV’s or Electric Vehicles work just about any where. We
put EV rovers on the Moon and they work great. EV’s do not burn anything!
They do not need oxygen to function. Solar energy can easily be converted
to electricity and is exactly what powers most satellites in outer space. So
when you take your EV into the Galaxy, you are ready to rock and roll on the
highways in the Galaxy. But putting aside this meager bit of humor, I want
to get serious about electric vehicles and in particular their high voltage
safety and the use of proper design elements in building a conversion
vehicle.
This book is not a how to do guide although Chapter 9 speaks to converting
a vehicle as an example of how the principles are applied to a create a
“road-worthy” conversion vehicle. The Guide provides insight that is not
readily available for electric vehicle converters today. The author’s
experience in the automobile industry is extensive and he brings that
knowledge to help converters understand the reasons for doing things “OEM
automotive-like” and the potential consequences for not doing items that
way. The choice is yours on how to build your EV Conversion; this book
gives insight into how to do your conversion with proper focus on safety
from many different perspectives. I recommend that you read this book
carefully with an open mind; the only difference in doing it better is
knowledge that you can gain here and a few extra steps and pennies.
I have read many preambles from suppliers about their parts/services and
the need to be careful. I am going to paraphrase what is stated very well in
CafeElectric’s Owner’s Manual. Please read this.
WARNING!
READ THIS PAGE TO SAVE LIVES
This book is only intended to provide basic guidance for elements of
doing an electric vehicle conversion and should be used by qualified
and experienced installers/builders. Electric Vehicles use Fatal
Voltages (120 to 300+ volts). Do not attempt to work on them
unless you are trained in safe design and working practices specific
to Electric Vehicles.
A vehicle using the various components described in this book can
be capable of killing people!
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This can occur both from high voltage shocks and due to many other
methods including driver error and unintended acceleration. It is the
responsibility of the vehicle designer, installer and builder to insure a safe
work-process and finished product.
The fine print: Very Important!!
The author of this Converter’s Guide to the Galaxy has no control of third
party procedures used in the selection and installation of the components
mentioned in this book or the modifications that may be made to a vehicle
based on guidance provided. The author assumes no liability for vehicle
functionality or safety after third party installation of the EV conversion parts
either recommended or not recommended or advice given. It is the
responsibility of the vehicle designer and component installer to test and
qualify their application and to insure proper safety and functionality. The
author assumes no responsibility for the applicability of these guidance
principles and recommendations in any use.
Futhermore:
The recommendations and guidance given are intended for use in
experimental vehicles and can be very dangerous if not operated properly
and responsibly, therefore the reader/modifier/operator assumes all
liabilities and risks associated therewith.
With the purchase of this book the reader/modifier/operator assumes all
risks and acknowledges acceptance of said risk with the purchase and use of
this book to modify, convert and operate electric drive vehicles. Additionally,
with regard to design or other recommendations and/or product
recommendations, the reader/modifier/operator is solely responsible for
determining their applicability and suitability for use, for the purpose
intended by the reader/modifier/operator.
The purchaser(s) of this book agree(s) that they will insure that the
purchased products and methods used to convert an existing vehicle will
only be used in a safe and lawful manner consistent with the laws, rules, and
regulations of the geographic area of the product operation and will assume
all risks and liabilities associated therewith and will hold the author, its
agents, employees, officers, suppliers, publisher, and vendors harmless.
Please note that is not to indicate that EV’s are unsafe or dangerous. If
done properly EV’s are very safe. The purpose of this introduction is give
this simple advise:
Be careful and respectful of high voltage, it can kill you.
Enjoy this guide and please update me with your experiences and
suggestions to improve this book. Technology changes daily in our lives and
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it will not take long before there are better ways to do things than what is
indicated here.
But most important is to enjoy your experience converting your gas
car/truck to electric drive...it is the future and the future starts today. That
you can count on!
Respectively submitted,
Richard W. Marks
President
EnVironmental Transportation Solutions, LLC
Detroit, MI
www.EcoVElectric.com
RWMarks@EcoVElectric.com
Biographical background on author:
The author has always been interested in mechanical and electrical things.
From early ages he took things apart and put them back together. He took
that interest to college and graduated from University of Maryland with a
BSME (Mechanical Engineering). He then went on to Cornell University and
graduated with a MSME. He was recruited by General Motors Research Labs
and went to work with GM in Warren, MI. He decided early on he wanted to
get the experiences necessary to become a Car Division Chief Engineer.
While that never happened, he did get a variety of great experiences in
areas of vehicle structure, safety, durability, ride pleasibility, weight control,
international structures program coordination, aero dynamics, chassis
systems, and electric vehicles.
He spent 25 years with GM, but his last 5 years were involved the EV1
electric vehicle program and with EV conversion programs. He worked on
the vehicle systems and assembly side and was involved with all the
engineers and management team on the entire vehicle. He then initiated an
activity to develop EV conversions that GM and its manufacturing partners
could build in their own plants. While the EV1 was exceptional, it was also
very expensive to develop and build. Conversions offered GM an opportunity
to market and sell a much lower price EV to the commercial and consumer
markets. He and his team built the first Chevy S10 conversion for GM and
GM took that to production, but not with the author involved or in the way
he had originally intended. The S10 GM built was costly and did not do very
well in the market for many reasons.
After the S10, he pursued a relationship with Toyota to build a Geo Prizm
conversion in the Fremont, CA plant. That project got relatively far along,
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until GM and Toyota could not resolve financial issues. Then his team
converted a Geo Tracker 4 door to electric drive for a management
demonstration and it was accepted as a worthwhile project to continue. The
team pursued a relationship with Suzuki to convert the Tracker in the CAMI
plant in Canada. Suzuki got very involved in the project and wanted to do
this. Between the Toyota and Suzuki projects, the author made many trips
to Japan and Europe and met with many of the suppliers making EV parts.
Tracker was coming in initially too expensive and the team was told to
reduce the cost by 30% if it was ever to reach production. Six months later
the team had reduced costs more than 30% but GM decided they had
changed their minds. The author then went off and pursued a couple other
conversions.
One was going to be a low cost Postal Truck conversion (never built), well
before the USPS issued their RFP for one in the 1998 time-frame. The other
was to convert a small car, the “Chevy,” being built for the Mexican market
(Actually it was a German Opel small car produced in Mexico). This project
was coordinated and guided with two outside suppliers who had a great deal
of electric vehicle experience. Two cars were converted. The one selected
was outstanding and demonstrated how simple and low-cost a small car
conversion could be. The car did not have air conditioning, but did have
everything else. It went 65 mph and about 50-60 miles on a charge. It
could be assembled in Mexico on the assembly line and brought to the US
and certified. But again GM got cold feet and it was at that point that the
author decided that his commitment to EV’s was far greater than GM’s. He
left GM and walked out the door after nearly 25 years.
The over the next 6 years, the author took on two jobs with a couple of Tier
1 suppliers to the major US OEM’s. He got great experiences to complement
his GM experiences. He learned how to quote projects, work with Tier 2 & 3
suppliers, did supplier development, learned quality systems, did Process
Sign-Offs and Production Part Approval Processes, worked with
manufacturing sites and even set up a low volume assembly line to build a
specialty automotive truck. All of this was done as he continued to be in
charge of the Engineering & Design Teams, and responsible for Project
Management and Profit/Loss. Both jobs ended when both companies reorganized under new management from outside of the US.
At that point the author came back to his passion for electric vehicles and
started a consulting company on EV’s, EnVironmental Transportation
Solutions, LLC. He consulted for two companies trying to develop
neighborhood and highway electric vehicles. Both companies failed to find
investors and pay him for his work so finally he left to do his own roadworthy electric Low Speed Vehicle. He brought his work back to Michigan
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which included several prototypes he, with the help of others, had built (at
his expense.) The EcoVElectric is the product his company is working on to
get funded. Hopefully, if there are any proceeds from this book, they will go
to help EcoV become a reality. So thank you for buying the Guide! It should
help the EV cause in many different ways.
Lastly, in 2007 he joined the Electric Automobile Association
(www.EAAEV.org) and got involved in creating a new Michigan Chapter. His
goal was to help the EV converters of the EAA to understand better how to
improve their conversions in many different regards. His focus has been on
safety and reliability. This Guide is a result of that desire.
Join EAA; it is a great organization and they will help you with your
conversion, too.
UPDATE: A lot has happened since I started this book. In 2008 there were
only rumors of up and coming electric vehicles and plug-in hybrid electric
vehicles. Today, in 2015, there are more and more choices for people
interested in EV’s. Unfortunately most are very expensive but to reduce the
price there are number of incentives or tax credits, both at Federal and State
levels. While I don’t particularly support tax breaks for the wealthy, they do
exist and if you make enough money or lease an EV you will benefit.
The interest in doing EV Conversions has lessened since a good EV
conversion can still cost a lot of money and hardly competes with today’s
EV’s and all their fancy electronics. One should note that EV’s are being
greatly subsidized by both the Government and more by the automakers.
Nobody today is making any money on EV’s, NOBODY.
What is missing in today’s World are affordable EV’s for the masses. Be sure
to check out my company EcoVElectric.com. Conversions can be an attempt
to build an affordable EV and if that is your intent then my book may be of
help to you doing it safer.
Best of Luck to you!
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Chapter 1: The Art of Designing a “Real” Vehicle or an EV
Conversion Vehicle
Congratulations! You have made a conscious decision to learn more about
converting old generation, oil-addicted Internal Combustion Engine (ICE)
vehicles into next generation clean technology transportation solutions.
Electric vehicles are coming and the pressure for the automotive OEM’s
(Original Equipment Manufacturer) to build them is growing daily. There is
much available to read about EV’s and why they make so much sense.
There is controversy as well: are EV’s really good for the environment? But
besides that, there is definite certainty that EV’s will reduce our Nation’s
dependency on foreign oil, improve the air quality in our cities, and can
provide new long lasting jobs in America through the building of EV’s and
their associated parts and systems. All it takes is action and desire. You
have shown the desire! Now let’s take some action!
Electric vehicle technology is a disruptive technology today for the OEM’s
and for all the industries supporting ICE technology (Interestingly, 100years
ago, EV’s were the mainstream and oil burning gas engines were coming on
strong because of cheap oil.) EV’s will change everything we know about
cars today and the consumers will love them. They will require a whole new
way for the auto industry and support industries to function and operate
profitably. EV’s do not have the complexity of ICE’s resulting in less
maintenance and repair. There are no gas fill-ups, no oil changes, no
emissions controls, no tune ups, no exhaust systems and with some advance
technologies, like regenerative braking, there will be significantly less brake
service. All these items will affect auto dealership and after market service
industry dramatically.
For us the consumer, it sounds great and we can’t wait; but there are dark
forces in the Galaxy that do not want this to happen and are dragging their
feet. We have seen these forces operate particularly over the last 15 years,
since 1994 when California proposed a ZEV (zero emission vehicle) standard
which would have require 10% of a large OEM sales in California to be ZEV’s.
I was at General Motors at that time and joined forces with the GM EV team
to develop and produce the GM EV1. In 1993 actually diverted myself away
from the EV1 to get involved in conversion vehicles. GM spent nearly a
$1,000,000,000 to develop and produce the 1000 EV1’s (This translates to
about $1,000,000 a piece for the each EV1 they built and leased and it
included all the R&D, tooling, purchase of very limited production parts,
manufacturing and sales/marketing).
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Competing with the clean sheet design of the EV-1 were conversion vehicles
that were much more likely to be significantly lower cost to the consumer.
The GM EV technology people were against conversions at first because they
could do so much better theoretically with a clean sheet design; but
someone has to pay for all of the newer technology and that person is you,
the consumer or GM Corporate as a longer term investment.
These were exciting times and the GM technology people were eager to
make ground-up EV’s happen. But EV’s are not new and in fact have been
around and continue to come around about every 10 years for the last 100
years. But today, the times have really started to change. Oil this week was
nearly $140/barrel and the price of gasoline has hit $4.10/gal as a National
average and everyone expects gas will continue to rise higher; $4, $5, $6,
$8, $10/gal? Climate change and carbon emissions from burning oil are in
the forefront of everyone’s mind as well as. Also air quality is a concern in
every populated region of the World. So the question is when will I be able
to buy an EV? The answer provided in this guide is RIGHT NOW!!!
How hard can a conversion really be?
The task to design a “real” or a production-like product that behaves the
same way as contemporary vehicles of today, is complex and not easily
understood by those who have never done it by way of working with an
automotive OEM at the engineering level.
First, let me explain my term “real.” A “real” vehicle is designed to meet
specific customer expectations and when produced in quantity delivers on
that promise and does so within the budget planned and the time allotted.
What does a real vehicle have to do? It is the integration of hundreds of
parts working together in the context of a higher basic plan. Things do not
happen by accident; they happen because of the plan.
Systems integration is one of the least understood terms and is the one task
that separates the good, the bad and the ugly from the great. Systems
integration is making the whole greater than the sum of the individual parts.
How is that possible? Here is a simple case in point. Search the whole
galaxy (Earth will do) and find the very best parts you can find from cars all
over. Find the best engine, best transmission, best seats, best doors, best
chassis, etc. Now assemble them to build the best car in the world. It will
not work, because the parts do not even fit together, they were never
designed to work together; that is the job of system integration.
Second, let’s define what is complex. The customer is complex in terms of
how he or she will use the product and what he or she will expect (you as a
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converter are a customer and so are the people you show your car to.)
Customer satisfaction is a mult-level list of factors that go into determining
how well the product will be received, ultimately sell and return satisfaction
over time. There are performance factors, such as ride comfort, handling,
quietness, driveability, operating range on a full charge (EV’s remember!),
and how well the vehicle handles the daily missions the driver gives it.
There are reliability and durability factors like economy of operation,
carefree operation, and quality of parts and systems. There are market
factors: perceived value (performance/$), styling, size and image. There
are safety factors like damageability, safety and security. And lastly there
are outside factors like repair costs, insurance cost, company provided
service & assistance, and warranty. Overall the task is to balance all these
factors and end up with a long-term happy customer.
Looking at recent history only supports how difficult the car business is. The
auto industry has not seen new competitors coming into the market. There
are exceptions in Asia, but even there, these new companies are learning
from older companies through partnerships. One area of interest in the US
has been alternative fueled vehicles including electric conversions. There
have been many new companies started and then collapse as they learn
about the complexities. In order to be successful at any thing, there are: 1.)
things you know, you know; 2.) things you know you don’t know but can get
help to solve those before it is too late and; 3.) (these are the killers) the
things you don’t know, you don’t know. If this last group is significant, you
will fail or worse, you will kill or injure someone, if not yourself.
This Guide will hopefully greatly reduce the #3 items and help you make
sound decisions based on knowledge, not just gut feel.
If you want to build a hobby car or a toy car, that is one goal, but if you
want a serious EV that you or anyone can use and depend on, that is
another higher level goal. So what does a real EV need to be able to do and
what are the issues that need to be addressed:
Range/Performance:
1. Battery life in miles
2. How far at highway speeds
3. How far at city driving speeds
4. 0-60 mph acceleration time
5. 60-0 stopping distance, feet
6. Curb mass, lbs or kg
7. How steep a hill and for how long and at what speed?
Vehicle Energy Efficiency:
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1.
2.
3.
4.
5.
6.
7.
8.
Energy consumption at 55 mph, Watt-hours/mile
Energy consumption on city driving schedule, Watt-hours/mile
Tire rolling resistance coefficient
Transmission efficiency
Motor efficiency
Controller efficiency
Charger efficiency
Battery charge efficiency, self-discharge characteristics, and storage
life.
9. Brake rotary drag, Nm
10. Aerodynamic drag coefficient
11. Accessory loads, Watts
Packaging
1. Impact speed at which damage starts to occur to drive system parts,
mph
2. Front and rear end packaging for crush
3. Crash deceleration pulse, g’s
4. Maintenance and service accessibility
5. Cargo volume, liters or cubic feet
6. Heating and cooling for passengers
Risk and Failure Modes:
1. Handling high voltages
2. Battery failure modes, consequences and prevention (this includes
everything from batteries gassing and exploding, leaking chemicals,
thermal issues, battery failures that leave you stranded, to even
containment of batteries and high voltage in accidents and roll-overs)
3. Protection of people inside and outside of vehicle in accidents
Vehicle Dynamics
1. Steering efforts
2. Steering response
3. Understeer
4. Coarse road noise
5. Vehicle structural bending frequency, Hz
Environmental Issues:
1. Ambient temperatures in which vehicle will be operated
2. Peak low temperature
3. Peak high temperature
4. Road conditions: salty, dusty, humid, dirt roads, rough roads,
potholes, twisty, up and down hills
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5. Typical weather conditions: rain, snow, fog, hot and sunny, mild, cool
and cloudy
6. Other issues, like car washes, alignment equipment, tire repair or
rotation, and service repair station jacking locations
7. On a broader scale: end to end lifecycle carbon footprint and
environmental impact (Meaning the total impact of
producing,(planning, designing, and testing) the vehicle; mining,
growing, refining, transporting, etc, the raw materials and
subcomponents; assembling and transporting finished vehicles;
operating (fuel, maintenance, waste products, storage, etc.) and
recycling (landfills, materials recovery), etc)
What does my conversion have to do?
This is an important question you need to think about carefully. If you plan
to build it and drive it on Sundays to EV events, that is one thing. If you
plan to use it daily to accomplish a specific set of missions, that is something
else. If you plan to use it to promote a business of converting cars, that is
great but also more complex because you have to do it right and safe so
nobody gets hurt regardless how stupid they might be and what dumb
things they might try.
The only thing that all EV conversions must be is SAFE. There are no
excuses for not taking the time, effort, and expense to insure no one will get
hurt with your EV conversion. This is not an absolute black or white, but
rather various shades of grey or understanding the risks and consequences
with each decision you make. This guide will tell you how a reasonable high
quality conversion on a limited budget should be done as if it were done by
someone who understands the issues an OEM would consider. Why mention
OEM’s? Well think about the complexities of modern automobiles and how
reliable today’s cars are and how long they last. This is not by accident. In
a conversion we are using maybe 75% of the original car that the OEM built
(frame, suspension, brakes, steering, body, accessories, handling, ride,
crash worthiness, etc.). This saves you time, money, and aggravation. This
is important and this is why you don’t want to screw up what the OEM’s have
spent millions of dollars validating and testing.
Where Do I Start?
The first question is how much do you want to spend converting an existing
vehicle? This answer will change as you learn more about your options.
The second question is how far do you want it to go on a charge? This is
based on how fast (top speed) do you want your EV to go and how fast do
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you want it to accelerate? You will need to decide what will be your typical
driving cycle (speed, distance and terrain.)
Answering these questions starts to frame your choices.
Limits to consider:
1.)
Vehicle rated Gross Vehicle Weight, Front Axle GVW and Rear Axle
GVW. (Grosse Vehicle Weight Rating is base vehicle, all fluids, all
options, all passengers @ 68kg (150 lbs) each and all rated luggage
capacity) These are important because they are the limits that
OEM use to design, test and validate the safety, durability,
reliability and integrity of their vehicles and in particular their
chassis and drivetrains. For crashworthiness, the problem gets
sticky since testing is done at maximum curb weight plus driver and
passenger. EV conversions can approach GVW, but special care is
needed relative to crashworthiness, since the battery weight is part
of curb weight. (Curb weight is base vehicle with options and all
fluids) GVW numbers are usually posted on a sticker in the front
door opening.
2.)
Weight of conversion vehicle as received and its front and rear axle
weights. Note what is missing, like full fuel or various missing
parts.
3.)
Weight of vehicle’s Internal Combustion Engine (ICE) parts
4.)
Weight of the EV parts that will be added back in to make the
conversion a functional vehicle. This needs to be as complete as
possible because many little missing things will add up significantly.
(To help you calculate and estimate how the center of gravity (CG)
will be affected by your choices, I suggest building a spreadsheet
that will calculate CG (example is in Chapter 9.) This requires
knowing the weight of the object and fore/aft location in the
vehicle. For the fore/aft location, I suggest using the front axle as
the 0” point from which everything else is measured.
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-x”
5.)
0”
+x”
Weight
IN
+Plus
Weight
OUT
- Minus
104.1”
The rear axle location is simply 0 + wheelbase. Any object in front
of the front axle is a negative dimension. You multiply (weight x
location) to get a value (note, added parts are + weight and
deleted parts are - weights.) Do this for all the parts and then add
all the weights in a total sum of total vehicle weight and add all the
weight x location products into a sum. Then divide the weight x
location sum by total vehicle weight and you get the location of the
CG relative to front axle center.
For an example, we will use our recent Cavalier conversion
(Chapter 9). We took the weight of the Cavalier as received
without engine, fuel tank, fuel, exhaust system, AC system, and
cooling system. We used race car scales to get the four corner
weights. The first two entries into our spreadsheet were front axle
weight: 1690 lbs and rear axle weight: 951 lbs. Front axle is at 0”
and rear axle is 104.1” We then estimate everything we could
possibly think about going into and out of the vehicle. For
example, we eliminated the spare tire with jack & tools. The
weight is coming out so it is negative or -38.9 lbs at 113”. The
electric motor is an addition at 156 lbs and is located just forward
of front axle or -2” (note the negative location). As you complete
this analysis you have a complete Bill of Materials, with a running
total of the weight of your conversion and the CG location. You can
compare front and rear axle weights to the limits you have set.
You can take your model and add passengers & cargo to see where
the vehicle is at GVW. But what is really useful is to put the
batteries in different locations and see the effect on overall vehicle
CG.
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6.)
Add and subtract all the above to calculate and set your GVW limit.
The differences will tell you how much battery weight you have
available to complete your vehicle.
7.)
There are things you can do to help yourself gain more reserve for
batteries. Remove content from the vehicle that is not needed,
such as insulation materials in the interior or hood blankets for
noise control, all the miscellaneous brackets, tubes, hoses, clips,
shields associated with a gas engine vehicle. Installing lighter seats
or aluminum wheels are other options if available. If you have a 5
or 6 passenger vehicle, you can eliminate the center seating
positions and pick up 150 lbs person in the GVW (but make it
obvious that those positions are no longer available for seating.) If
you need more, you can look at substitute materials for body
exterior panels, sometimes the OEM’s will make steel hoods
standard but have an aluminum hood for use in heavier models.
Just find yourself a good race car guy and ask him what he would
do to lighten a car!
Some basic observations.
1.)
People like pickups because they can carry a lot of cargo weight
(GVW) and have lots of space for batteries. But remember if you
substitute 800 lbs of batteries for the 1000 lbs payload capacity,
you have a truck that can only carry 200 lbs. But on occasion you
can typically exceed GVW for short periods since many
manufacturers understand pickup trucks are often overloaded and
they are designed for a slight reserve.
2.)
EV’s do not carry a lot of “fuel” or energy. The 800 lbs of
batteries is equal to about the energy in a quart of gasoline! (1
gallon of gas is about 125,000 BTU’s or 36.4 kWh) So how can an
EV go 40 miles on a quart of energy? EV’s are very efficient where
as gas engine powered vehicles are not. Internal combustion
engines operate as heat engines and all of this heat generated from
the burning of fuel and the friction of the moving parts must be
removed; the cooling system and exhaust system do that by
throwing it away. The best ICE’s operate at about 20% efficiency
or in other words, 80% of the energy is thrown away and does not
move you down the road.
3.)
Because the energy requirement for moving a vehicle down the
road is little, the more work you have to do moving a heavy vehicle
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down the road fast or up the hill eats up your energy quickly. EV’s
like to be light weight so they do not consume less energy to move.
This is most apparent when you consider the rolling resistance of
your tires. The rolling resistance coefficient relates the force
required to turn the tire over with a given load on it. Typical tire
rolling resistance coefficients are in the range of 0.010-0.015. This
means if you have a truck and it weighs 4000 lbs, the force
required to move it down the road is 60 lbs. (4000X0.015). Force
is related to work (or energy), which is force times distance, ft-lbs
(N-m) and force is related to power, which is force times distance
per unit of time, ft-lbs/sec. (N-m/sec or Watt) Note that power is
the rate you are doing work so as you go faster you need more
power to continue to move.
Let’s take the 4000 lb (17,792 N) truck and drive it at 62 mph (100
km/h). It takes 7.4 kW of power to just roll down the road (17792N
x 0.015 x 100000m/hr/3600sec/hr/1000W/kW) and 5.9kW at 48
mph (80km/h) and 4.4 kW at 36 mph (60 km/h). So if you are
driving for an hour at those speeds, the energy you take out of
your batteries to overcome rolling resistance at 62 mph is 7.4kWh,
but you did go 62 miles!
But that is not all that is coming out of your batteries to move you
down the road. Aerodynamic drag is proportional to the square of
the speed, the drag coefficient (Cd,) the frontal area, and density of
air. Trucks are bad for aero (high Cd) and have large frontal areas.
A truck could be taking another 15 kW at 60 mph, 8 kW at 50 mph
and 3.4 kW at 35 mph. All these are additive so now your truck
doing 62 mph is consuming 7.4 + 15 = 22.4 kW and if you do this
for an hour that is 22.4kWh, which means you won’t be able to go
for an hour and will probably be limited to under 30 miles.
4.)
Size does matter here and the power and energy consumption for a
pickup is 50% more than a subcompact car. Now you know what
your trade offs are. (But there are more losses too; there are
motor/controller/gear box efficiencies, brake drag, electrical
accessory load to just hit the top five. We will not deal with them
here at this time. In the examples that follow, you will see why we
do the things we do to try minimize these other losses, too.)
16
Industry Standards, Guidelines and Federal Safety Standards that
should be noted.
1. Federal Motor Vehicle Safety Standards (FMVSS) identify testing
conditions and standards for those tests that are all OEM’s are
required to satisfy. These can be found at
http://www.nhtsa.dot.gov/cars/rules/standards/FMVSSRegs/pages/Part571.htm Title 49: Chapter V - National Highway
Traffic Safety Administration; Department of Transportation; Part 571
Federal Motor Vehicle Safety Standards ; Subpart B—Federal
Motor Vehicle Safety Standards 571.101– 571.500
2. SAE (Society of Automotive Engineers, International) publishes
engineering guidelines (May 2008), often referenced in FMVSS.
a) J1715 Electric Vehicle Terminology
b) J1766 Recommended Practice for Electric and Hybrid
Electric Vehicle Battery Systems Crash Integrity Testing.
c) J1772 SAE Electric Vehicle Conductive Charge Coupler
d) J1773 SAE Electric Vehicle Inductive Coupling
e) J1797 Recommended Practice for Packaging of Electric
Vehicle Battery Modules
f) J1798 Recommended Practice for Performance Rating of
Electric Vehicle Battery Modules
g) J2288 Life Cycle Testing of Electric Vehicle Battery
Modules
h) J2289 Electric Driver Battery Pack System Functional
Guidelines.
i) Energy Transfer System for Electric Vehicle – Part 1:
Functional Requirements and Systems Architectures.
j) J2344 Guidelines for Electric Vehicle Safety
k) J2464 Electric Vehicle Battery Abuse Testing
l) J2380 Vibration Testing of Electric Vehicle Batteries
m) J2358 Electric Low Speed Vehicles
n) J1742 Connections for High Voltage On-Board Road
Vehicle Electrical Wiring Harnesses – Test Methods and
General Performance Requirements
o) J1673 High Voltage Automotive Wire Assembly Design.
UPDATE: SAE continues to publish new Standards for
Electric Vehicles; please check SAE Standards for new
information.
3. IEEE
4. UL
17
Chapter 2: High Voltage Safety and Overall Vehicle
Safety/Reliability/Durability
This is a subject that is critical for all to understand. I will try to provide
“facts” by which you can make your own decisions. My purpose is to
educate you with my knowledge of what OEM’s are concerned about so at
least you will hopefully understand better the compromises you are making
and the specific consequences you and others will face.
Most of us would like our conversions to be:
1. More than science-fair projects on wheels
2. Reliable so we count on our conversion to do certain jobs for us day in
and day out without wondering if it will complete its mission.
3. Safe to operate reliably both electrically and mechanically, regardless
of weather.
4. Safe as any normal vehicle and if we are in an accident we or anybody
else would not get hurt because of what or how we have done the
conversion.
5. Comfortable that if we take riders or children out in our vehicles that
we are not exposing them to something that could cause harm to
them.
6. Reliable and not require a lot of maintenance and service work or
“adjustments” all the time to keep it working. I call it “Plug and Play.”
7. Fail safe enough that if we forget to do something, somebody
unknowingly won’t get hurt including ourselves.
These are choices you have to make and if you decide to make trade offs on
safety, performance or reliability, then go ahead and do it, but BE AWARE of
the consequences that might result for you and others.
High Voltage Warnings:
High voltage can kill you! IEEE has established that any voltage over 44 V
has the potential to overcome normal skin resistance and cause electrical
shock. This varies by individual but it is a scientific fact. But it is not the
high voltage as much as the current that will kill you. We have all probably
worked with 120 VAC electricity in our homes. And have at least once
touched the wrong wires and got a shock; maybe even tripped the circuit
breaker. Household current is usually on a 15 Amp circuit breaker which
limits the current exposure to 15A.
In your EV you maybe operating at 120 to 170 VDC or more, but your
batteries maybe be capable of putting out in excess of 1000 A! This will
kill or burn you if you do something wrong or unintentional.
18
Does this mean EV’s are inherently dangerous? No, EV’s can be very safe
and perhaps even safer than standard gasoline vehicles but it does not come
without significant study, planning and sound execution. If you don’t
understand this danger, you will likely get into trouble and not even realize
it. Our purpose is to provide you with education so you can do it right and
do it with the proper precautions. That is our purpose.
What should you do about this? CAUTION and RESPECT are the words.
Some basic rules:
1. Get advise or help from “knowledgeable” experts (the issue is what
is a “knowledgeable expert?”) I would look into their tool box. If all of
their tools are covered in black electrical tape, that is a step in the
right direction because they have had accidents and have learned
something (hopefully). Check the tools again and see how many are
burnt from dropping on high voltage connections, the fewer burnt tools
the better unless they are just plain lucky. Last check their hands and
see how many burn marks they have from shorting batteries with
wrenches in their hands. I have seen people where their wedding
rings were literally melted off their fingers (very ugly burn). In fact,
many mechanics will take off all conductive jewelry when working with
high voltage. Good advice.
2. Never, Never, Ever work alone with high voltage. If you do
something wrong it is important to have someone there who can help
you and get you help. Never grab the person being electrocuted, use
a non conducting device to break the connection, like a wood broom
stick.
I am not trying to scare you, only put the fear of respect into what you
are doing. You are working with deadly levels of electricity. With
proper precautions, none of this is ever going to happen or cause you
any harm.
3. Plan for the worse and then plan to avoid those things. This is
basic Design Failure Mode and Effects Analysis (DFMEA). This is a
science of understanding what the potential failures could be, the
effects of those failures and how to make changes to eliminate those
failures. In this case the failure is electrical shock. This science was
developed by aerospace and automotive and is used world wide with
almost all product design today. For example, we have all dropped a
wrench accidentally. It happens to the best of us. If you drop a
19
wrench on a battery what are the possible failure modes? The wrench
shorts out a battery. A shorted battery like this can deliver 1000A
across the wrench and will be very dangerous. It will cause sparks
and even flames. It will melt the wrench and if you are holding it, you
can get burnt very badly. So now we understand the failure mode and
the effects, so how do you prevent this? Insulating all of your
connections and battery posts is one preventative solution, eliminating
the need to connect batteries with mechanical tools, and possibly
wrapping all your tools in insulating materials. And there are other
ways that I am sure you can come up with, the issue is there is a need
to do something to prevent this failure mode from occurring.
4. Use gloves or better yet use insulated gloves
5. Never put your hands across a potential short – electricity
entering one hand and exiting the other puts the current across your
heart, which is not good.
6. Don’t stand in water – since your body becomes the ground circuit
particularly if your high voltage has a ground to earth (and it should
not!).
7. Wrap your tools in insulating material – if you drop a wrench you
will not created a short as easily
8. Provide a Master Disconnect Switch for Service – this is used to
open the pack so as to not expose the person doing service to the
whole pack battery voltage.
9. Insulate all your connections so as to not leave exposed
conducting connections
10. Simply be careful and respectful of high voltage. It
can kill you.
High Voltage Requirements for a “Safe” Electric Vehicle (these are
adapted from 1999 EV America Technical Specifications; see bibliography):
20
1. Vehicles shall not contain exposed conductors, terminals, and contact
blocks of devices of any type that create the potential for personnel to
be exposed to 50V or greater. Access to any high voltage component
shall require the removal of at least one bolt, screw or latch. Devices
considered being high voltage components shall be clearly marked as
HIGH VOLTAGE with wiring in orange color or orange sleeving, if at all
possible (orange battery cable needs to be specially ordered and then
still may not be available in small quantities. I have used orange
electrical tape on the ends high voltage wiring. Standard automotive
gage orange wiring (10 AWG to 22 AWG) is readily available.) These
markings should be installed at any point the voltage can be accessed
by the end user.
2. Propulsion power shall be isolated from the vehicle chassis such that
leakage current does not exceed 0.5 MIU (Measurement Indication
Units; at 120 VAC at 60Hz: 1 MIU = 1 mA). The human body is less
sensitive to higher frequencies, such as what might come out of a high
frequency controller, so the current is expressed in MIU (there are
devices you can buy to make these measurement, called current
leakage testers). To make these measurements, simply place a low
current ammeter between potential high voltage and ground on the
chassis and ground (earth).
3. Charging circuits shall be isolated from the vehicle chassis such that
ground current from the grounded chassis does not exceed 5 ma at
any time the vehicle is connected to an off board power supply in
accordance with UL Standards. Read charger section for more
information.
4. Vehicles shall be equipped with an automatic disconnect for the main
propulsion batteries. The disconnect device shall operate to isolate the
propulsion circuits any time the chassis becomes energized from
contact with the propulsion battery or its associated circuits. This
disconnect shall be capable of interrupting maximum rated controller
currents.
5. A manual service disconnect shall also be required. A decal or label
should be affixed to driver’s sun visor. A similar decal should be
affixed to the inside of the vehicle such that it is clearly visible to
individuals located outside the vehicle through the lower left-hand
corner of the rear window. This disconnect should be operable from
the driver’s seated position. It shall require the following capabilities
a. Manual action to break the connection
b. The disconnection is physically verifiable
21
c. The disconnection does not create exposed conductors capable
of becoming energized while exposed.
d. The key-switch may be used to satisfy the operability portion of
the manual service disconnect requirement, if it interrupts all
control power going to the controller and the main battery
contactor(s). This disconnect is not required to operate under
load.
6. Safety interlock system – The vehicle shall be prevented from being
driven with the key turned on and the drive selector in the drive or
reverse position while the Vehicle’s charge cord is attached.
Additionally, the following interlocks shall be present:
a. The controller shall not initially energize to move the vehicle with
the gear selector in any position other than PARK or NEUTRL.
b. The start key shall be removed only when the ignition switch in
the “OFF” position
c. With pre-existing accelerator input, the controller shall not
energize or excite such that the vehicle can move under its own
power from this condition.
7. Operation of Hazard lights – Hazard lights should be capable of at least
one hour of continuous operation in the event of shutdown or isolation
of the main battery pack or failure of the DC-DC converter system.
This subject can be debated; there are two options. First, my
recommendation is rather than carry around a weight of a standard
extra car battery to provide 12VDC along with its charger, simply use
a good reliable DC-DC converter to reduce your battery voltage to a
regulated 13.6VDC. Wire the DC-DC directly to the batteries so that it
uses half of the pack for voltage & power. Second method is probably
safer and involves adding a small SLI battery with the DC-DC tied
across the pack to charge the battery. The SLI battery is not a deep
discharge battery so your 12V system will be basically powered off the
DC-DC anyway. However in case of a high voltage shut down, the SLI
could power your hazards lights. The question is if your EV batteries
or major system fails and you lose all power, will your DC-DC lose
power as well. This may depend on how the DC-DC is wired into the
system and what the failure occurrence is.
8. State of Charge Indicator – The vehicle shall include a state of charge
indicator for the main propulsion batteries. Indications should be
accurate to ±5% of full scale.
9. Connectors – Low voltage connectors should follow SAE or standard
automotive requirements. High voltage connectors should utilize
22
obvious labeling, locking devices, should be keyed to prevent missconnections, and should be moisture proof.
23
Chapter 3: EV Batteries for Conversion Vehicles
BATTERIES
Now let’s talk about batteries which are where EV’s all begin. Since most of
us have limited budgets we are probably looking at lead acid battery
technology. What are the issues that need to be considered?
1.)
Safety is number one
2.)
Availability
3.)
Size and weight and ability to package into the vehicle’s available
space.
4.)
Long term cost of ownership or life cycle cost based on your
expected duty cycle.
5.)
Voltage is a secondary issue since you are trying to balance the
weight limits with the voltage limits. If you can handle 6 volt
batteries and get more lead (weight) in then you would get with
fewer 12V batteries, use 6V. Lead acid batteries (PbA) have a
specific energy that is about 30 Wh/kg. If you are looking for
10kWh of battery energy, then 10000/30 = 333 kg or 735 lbs of
battery weight. But remember, more batteries mean more
connections and more racks & restraints and usually more problems
with battery pack balancing and management.
6.)
Charging goes hand-in-hand with any battery pack system design.
This needs to be factored in as well at the front end of the design
stage not after it is all done. More on this later.
7.)
“Active” Battery monitoring and balancing the pack. Large strings
of batteries should see the same current going through all of them
and the voltage should be very close to nominal x number of
batteries. If the batteries start to drift apart on a voltage at full
charge, you are on the edge of a cliff. There are many reasons why
batteries can drift apart. Battery manufacturing variability, age of
batteries, particularly if the batteries are not the same age when
bought, temperature variation in the batteries (some are in a hotter
area or are seeing less cooling, maintenance (if required) is not
done correctly to all batteries, or poor charging algorithm is
damaging the batteries. You want your entire set of batteries close
24
when in full charge or discharged. This imbalance can happen for
lots of reasons. Primary reason is the quality level of the batteries
you are using and even well known manufacturers have drift in
their manufacturing processes over time. My recommendation is to
buy batteries from the same lot made on the same day and made
relatively recently. You can “cheap” out and use whatever you find
lying around but you will get mostly problems in the long run. You
may even want to take your voltage meter to the battery store and
measure each battery you intend to buy. If one falls outside the
others, get another one. How close should they be and be
maintained at? Good question. My goal is to keep them within a
±0.1V of each other. Is this easy to do? Absolutely NOT. This gets
into a lot of complications but it rests on the battery, charger, and
the monitoring system.
8.)
What happens when the batteries start to drift apart? First you will
lose range and than the range will get worse. Batteries don’t like
two things: 1.) being overcharged or 2.) being over discharged.
a. Overcharging will cause gassing within the battery which results
in loss of electrolyte and possibly swelling of the battery case
(sealed batteries).
b. Over discharging can kill your batteries to point that they may
not return to normal.
c. A typical lead acid battery is considered 100% discharged at
10.5 V. You should never take your batteries to this voltage.
About 80% depth of discharge is all you want to use and this is
approximately 11.4 V/module (open circuit, no load.)
d. So what happens with an unbalance pack? Your drive-system is
expecting a certain voltage and current and if one battery is
down in voltage it will deplete more rapidly than the ones around
it. This can ruin this battery further or even fail it. As a battery
fails it will increase in resistance which lowers the current flow,
this commonly is a result of sulphate crystals covering the
positive plates or battery running out of water. On the charging
side, you can ruin your good batteries. Most chargers charge to
certain voltage limits for the whole pack, if one battery is down
(your bad one) this will result in overcharging all the other
batteries. The charger is looking to charge the entire pack to
that set voltage limit, which can cause gassing which releases
hydrogen, oxygen and consumes your electrolyte thus reducing
the chemical performance of your battery. To see this, let’s say
you have a 144VDC nominal pack with 12 PbA flooded batteries.
Let’s say your charger charges the batteries to the max limit of
16.2 VDC x 12 = 194.4VDC; but say one battery is down 2V,
25
then the others will be charged higher until the pack gets to
194.4 or the other 11 batteries will be charged to 16.4V. This
voltage level is above the max limit and will cause more gassing
and possible damage to the good batteries. This does not
happen immediately but the trend is set and your performance
will be a continuous degradation. If this unbalance is not caught
early, you may ruin the optimum performance of the whole pack.
9.)
“Passive” Battery monitoring – this is a process of monitoring your
batteries and understanding what they are doing. Monitoring is
done in operation (watching current and voltages), in charging, and
in maintenance modes. A simple way to measure batteries is with
a voltage meter. You can build a device with a rotary switch and
wires to each battery terminal and can read quickly what the
voltage is across each battery. A device like the e-Meter (now
Xantrex – Link 10 meter, seen below) is useful for monitoring
battery pack functions and provides a good “fuel gage.” It has
many useful functions, but it is a simple “passive” monitor not an
“active” battery management system.
Selecting Batteries – Factors to consider
Update: In 2015 there are many more choices for batteries. In 2008 there
were really only 2 battery chemistries for EV’s – lead acid and nickel metal
hydride. NiMH batteries were expensive and hard to get. Lithium batteries
were not available in forms acceptable for EV conversions. Today, a whole
new world has opened up, BUT high quality Li batteries are a major
challenge to find and use. I believe that Li batteries with the proper
chemistries are the Holy Grail for EV’s and Conversions. Li can provide 3X
the energy at 1/3 the weight and last 3X as long. Prices are rapidly coming
down as volumes have continued to grow. The major “type of battery” still
missing is higher voltage and capacity battery modules, similar to the 12V
26
lead acid modules. Modules are mono-blocks with cells in both series and
parallel. The World’s automakers are dragging their feet on standardizing
and sharing module sizes because they know that high volume, fully
automated assembly of modules will drop the price of EV’s drastically.
Now back to 2008!
1.)
Wet cell or sealed? This is an important decision and one that
should be made carefully. In my opinion, there is only one option
that is safe for use in a roadworthy electric vehicle and that is a
sealed battery. All OEM’s in the world provide sealed batteries in
new cars. These are a different kind of lead acid battery since they
are used for Starting, Lighting and Ignition (SLI). They are not
deep cycle batteries. Many of these are sealed flooded battery
technology since they must be low cost. Most after market
replacement SLI batteries are sealed as well.
2.)
Sealed batteries are usually of two types, gel-cell or absorbent
glass mat (AGM). Both have electrolyte but in a gel cell it is
suspended in a gel material and in an AGM the electrolyte is
sparsely (starved) stored in a glass mat. Both are sealed valve
regulated and can be dropped or cracked and will not spill
electrolyte in any position even upside down. Because they are
sealed they have recombinant technology which means that the
oxygen that is normally produced on the positive plate in all lead
acid batteries recombines with the hydrogen given off by the
negative plate. The “recombination” of hydrogen and oxygen
produces water, which replaces the moisture in the battery.
Therefore the battery is maintenance free and never needs
watering. Never mess with the valve regulator, never open the
batteries, and never overcharge the batteries. Do not buy
“additives” to restore bad/ruined batteries. If you do this, all bets
are off on your batteries. Just leave them be and they will work
great for you.
3.)
Gel battery or AGM? Both share similarities but gels have better
deep cycle life, superior shelf life, very rugged & vibration resistant,
better temperature resistance or less temperature sensitivity, and
offer the lowest cost per cycle (cost/life cycles). Gels are higher
initial cost, heavier, and require a voltage regulated charger and do
not want to be overcharged. If you want to build a dragster and
want high power (or the ability to deliver high current discharges);
Gels are not the right batteries for dragsters. AGM’s offer lower
initial cost and can accept higher charging voltage than a gel
battery but they do have shorter life cycle in deep cycle
27
applications. All these issues are a function of how you use your
batteries. Many claim impressive long lives and long mileage lives
out of their batteries. This depends of how deeply you discharge
your batteries. Most lead acid will do 400-500 cycles at 100%
depth of discharge.
4.)
Lastly, there is always new technology being developed and the
science is always changing and improving. What is good today may
not be the best tomorrow. There is much interest currently in Liion batteries, but in the last few years, the chemistries and
technologies have improved tremendously and continuously.
5.)
Wet cell batteries – The International Society of Automotive
Engineers, SAE has about 50 standards which involve electric
vehicles. These standards are developed over time and are
updated or eliminated if they become outdated. There are
references to SAE standards in most Federal Motor Vehicle Safety
Standards (FMVSS). Wet cell batteries are very difficult to make
compliant with these international safety standards. First, there
can be no leakage into the passenger compartment including while
conducting the roll over procedure following all crash tests. You are
limited to 5 liters from everywhere else. We are converting
automobiles for use on public roads and with that we have certain
responsibilities to ourselves, our occupants and those around us.
We are not building golf carts or fork lift trucks. Cars get into
accidents and people can get hurt. Cars operate in a variety of
weather and road conditions. People do a variety and sometimes
strange things with their vehicles. We need to recognize these
issues and make the proper decision for battery selection.
a. With that said, flooded lead acid batteries are not sealed, ever.
Adding a watering system does not seal the batteries. The
sulfuric acid is in a liquid solution and moves around. Flooded
lead acid batteries can never be mounted other than vertical
because the electrolyte will leak out. They can not be sealed
because of the gases released during charging and discharging.
The water breaks down into hydrogen and oxygen and escapes.
b. What happens when a battery is turned over, as in an accident?
They will leak acid and this can be in direct violation of SAE
standards and FMVSS requirements (see FMVSS 305 for EV
electrolyte spillage, battery retention, and electrical shock
protection.) If a battery is hit directly and the case cracks, most
of the acid will leak out. If they are in a crush zone in a crash,
28
they can literally exploded and spray acid everywhere. Sulfuric
acid is considered to be a hazardous material. In a car battery
the typical concentration is about 60% water and 40% sulfuric
acid. In addition, the solution also has lead concentrations in it
as well. When sulfuric acid comes in contact with human flesh, it
withdraws water, leaving a black charred carbon residue, in
place of living tissue. If you disagree, please read the MSDS
(material safety data sheets) that all battery producers issue.
c. Sulfuric acid is not flammable by itself but it can cause and
support a fire by reacting with other chemicals/materials and
liberating enough heat and/or hydrogen to ignite ordinary
combustibles and even cause an explosion.
d. What if I put the batteries into a sealed container? The
container can not be sealed because you must release the
hydrogen and oxygen generated during discharge and recharge
or you can have an explosion if a spark occurs. (Never put an
open/non-sealed contactor in a battery box!)
e. Another issue with flooded batteries is the release of sulfuric acid
outside the batteries, basically fumes. This residue can ionize
materials around it and conduct electricity from the battery. So
now you have your battery grounding to your car! These fumes
also corrode everything in sight, particularly your battery
terminals, cables, crimps and restraints. If you use metal
strapping to retain your batteries, these can cause shorts you
never even dreamt of.
f. But my biggest concern is crash-worthiness. FMVSS requires
that cars sold to the public by a manufacturer must comply with
FMVSS standards. The tests are numerous, but basically the
major tests are 30 mph front and angle barrier impacts, 30 mph
rear moving barrier impact, and side impact. After these tests
there is a small amount of acid that can leak and then the
vehicle is rolled over with the same limits on total leakage. It is
virtually impossible to meet these standards with a flooded lead
acid battery in an EV conversion. These are not arbitrary
standards but are standards developed to offer reduced injury to
people in accidents. If you review the NHRA rules for drag
racing both open wheel vehicles and motorcycles are not allowed
to use anything but a sealed battery. Other vehicles require the
batteries to be in a sealed fully enclosed container that will not
expose driver/people to its contents in event of an incident. In
29
these cases the dragsters open the battery containers when
charging and when they are running, they run only for a few
minutes.
g. MY RECOMMENDATION IS TO AVOID FLOODED LEAD ACID
BATTERIES IN A CONVERSION. Will flood lead acid batteries
power the car? YES. Are they road-worthy? NO! This is your
decision and now you know the consequences.
Where do I put the batteries?
1.)
As you determine your battery choices, this will become clearer, but
here are more things to consider.
2.)
Maintain vehicle GVW and weight distribution. A large part of
vehicle handling is weight distribution. If you start with a vehicle
that has 60% front/40% rear weight distribution and end with 40%
front/60% rear, you have changed the handling of the vehicle
tremendously. Is it still drivable? Yes/Maybe, but it will not do all
things the original car was designed to do. A heavy rear biased car
may under certain conditions want to spin the tail out in turns
(oversteer.)
3.)
Don’t put all the batteries at the front and/or rear end of the
vehicle, this too will affect handling. This creates a high polar
moment of inertia, which is what you have to overcome in order to
turn into a corner quickly. A car with high polar moment of inertia
will seem like a boat going into a corner. If at all possible try to
locate the batteries as centrally as possible but exterior to
passenger compartment. This provides the other benefit of putting
the batteries in the same area as the passengers who you are also
protecting with the crash structure that was originally designed.
Protect the people, protect the batteries. Putting the batteries in
the front or rear end has the potential for crash safety issues. In a
crash the vehicle crumples to absorb the energy of the impact, thus
softening the deceleration of the vehicle and reducing the injury
forces the occupants see. If your batteries fill the crash zone,
including the battery racks to hold the batteries, then you are
potentially preventing the vehicle’s structure to crumple and will
transmit higher forces into the passenger compartment which the
passenger compartment may not have been designed to with stand.
30
4.)
Battery pack containers, trays or racks. There are lots of ways to
do everything and many work quite well. Here are guidelines I
would suggest that you consider.
a. Now that you know where you want to put your batteries, how
do I hold them in place? They must be restrained and restrained
safely. If you answer, “I don’t get into accidents, I don’t really
care, It’s not that important;” You are WRONG. I have seen
examples on the Internet where somebody takes out the back
seat, lays down a piece of plywood and lays flood lead acid
batteries on the plywood and then wires them together...and
that is all. This is so incredibly dangerous! Say your batteries
are typical EV batteries and weigh 70-80 lbs each. You hit
something or someone hits you and you stop abruptly at 10g’s
(this is mild accident). Your 80 lb batteries are now flying with a
force of 800 lbs. I would not want to get hit by an 800 lb object
and your battery wiring will only slow them down a little.
b. Batteries need to be restrained and secured to the vehicle’s
structure. Again this means that the tray or support holds them
in position and secures them from being ejected in all directions.
Most batteries have features molded into the case that allows
hold down provisions, consider using these if possible. For
additional security I would recommend some form of hold down
over the top of the batteries as well (this can be a strap, or a full
cover.)
c. Since weight is all important, I would not recommend going to
the junk yard and picking up steel scrap and welding/bolting it
all together. Think about the supports and what they have to do
and you will probably come up with a better, but lighter solution.
Steel is easy to weld so it is usually used. Use the section
properties of the steel not just the gage. Rather than building
the support with 1½” angle ¼” thick, think about 16 gage
(0.063” thick) 1” square tube with a 16 gage flange welded to
the bottom to rest batteries on. This will be lighter, stronger and
less than half the weight. You could also weld a Z flange for the
perimeter frame with cross tubes of thin gage to stabilize. If
aluminum is available, use it because it will be half the weight.
Another solution could be to make the tray out of fiberglass or
fiberglass sandwich, if you can. Fiberglass is not reactive with
the battery acid. SEE PICTURE ATTACHED??
31
d. Insulating the tray for cold weather. The issue is how cold do
you want to operate the vehicle in? I prefer to store the vehicle
in the winter in a garage if available. If you want to operate
below 0oF and have the vehicle sitting outside in that weather,
you are probably in the wrong climate. EV’s like warm weather
and in very cold weather the batteries lose capacity quickly.
Battery heaters can be used but usually only when charging and
power is available to power the heaters. (A group 31 battery
can be heated with either a silicon heater pad on the bottom or
with a wrap around the sides. These heaters require 50W-80W
each at 120VAC. With 12 batteries that is 600W to 1000W of
power required. They must be thermostatically controlled to
typically 75o - 80oF. You obviously need them in an insulated box
to avoid heat loss. So can you use your traction batteries to
power your heaters while you are at work? A lot depends on
temperature, insulation and heater controls. My suggestion is
probably not but it depends on many things. Build it, measure
it, and decide for your self, but remember you have precious
little energy to spare and EV’s do not operate as efficiently in
cold weather, regardless of the battery issues.) If you put the
batteries in a box (and it can’t be sealed,) it must be able to
vent out the hydrogen if released. Be careful to not overheat
the batteries as to boil off the electrolyte and remember in
summer to take the insulation out so again as to not overheat
the batteries.
e. My recommendation is to allow the batteries to vent naturally to
the atmosphere through natural convection and avoid stacking
the batteries so that no air can flow around them. Batteries
operating at different temperatures will age differently and
eventually drive voltage imbalance in your pack.
Battery Facts to help you:
1.)
How much useable capacity does a battery have, based on standard
specifications given? The first thing I learned working with battery
manufacturers and on the General Motors EV programs was, “there
are liars, damn liars, and battery engineers” (this is a joke, of
course, but it illustrates that you need to be careful reading and
understanding the data that battery companies provide.)
2.)
Typical data (or standard data) are:
a. Model number
32
b. Nominal voltage of the module
c. CCA (cold cranking amps) @ 0oF
d. MCA (marine cold cranking amp) @ 32oF, (cold cranking amps
are the maximum number of amps that can be pulled from the
battery until 1.2 V per cell is measured and the cell is 100%
discharged under load)
e. Reserve capacity is a standard BCI (Battery Council
International) battery test that all lead acid battery
manufacturers subscribe too. It measure the minutes of reserve
capacity with a 25A load until the battery reaches 1.75V per cell
or 10.5 V with a 12V module
f. Nominal capacity at C/20. This is the critical measurement for
predicting range of the vehicle. This tells you how much energy
your battery can store which translates into how far you can
drive it on a full charge. Manufacturers of deep cycle batteries
usually will provide other capacities at various discharge currents
using the term C. C/20 is the current that can be drawn for 20
hours. C/5 is the current that can be drawn for 5 hours. (For
example a battery that has a C/20 capacity of 100 Ah (Amphours) will allow 5A to be withdrawn for 20 hours). In an EV
application with lead acid batteries running continuously, you are
most interested in looking at C/1 or C/2 rates (1 to 2 hours of
continuous operation). Many times this is not available, but IT IS
VERY IMPORTANT TO UNDERSTAND. Battery capacity “shrinks”
at higher discharge levels, meaning the faster you discharge
them the less usable energy they hold. For example the 100 Ah
battery at C/20 (5A discharge) will be about a 55Ah battery at
100A discharge (C/0.55 or 33minute discharge)...significantly
different. See Peukert’s Equation below for how to approximate
what you want.
g. BCI case size, which is a set of standard battery dimensions that
the whole industry uses. This standardization allows you many
different manufacturers making a “size” interchangeable battery.
h. Dimensions are usually given is length, width, and height. Be
careful to understand on the height measurement how this is
made and whether the terminals are part of this or not.
33
i. WEIGHT, the all important measurement. Everything being
equal, more weight means more lead and more lead means
more ability to store energy.
Peukert’s equation:
Peukert's Law, presented by the German scientist W. Peukert in 1897,
expresses the capacity of a lead-acid battery in terms of the rate at which it
is discharged. As the rate increases, the battery's capacity decreases,
although its actual capacity tends to remain fairly constant. Peukert’s
constant (dimensionless) reflects this non-linear characteristics. It is not
exact but fairly representative of what to expect. Typical constants are in
the range of 1.1 to 1.3 and vary with battery, even if same materials are
used. Larger plates, heavier plates reduce the effect somewhat and aging
increases the effect and the constant.
More commonly, manufacturers rate the capacity of a battery with reference
to a discharge time. Therefore, the following equation can be used:
t = H/((I * H)/C) ^ k
Where:
t is the hours to discharge at new discharge rate of I, Amps
H is the hour rating that the battery is specified against, such as 20 hr
rating
C is the rated capacity at H, such as 100Ah capacity at 20 hr discharge
rate
I is the discharge current in Amps that you want to know battery
capacity
k is Pueket’s constant
For an ideal battery, the constant k would equal one; in this case the actual
capacity would be independent of the current.
The Peukert law becomes a key issue in a battery electric vehicle where
batteries rated at 20 hour discharges are used(discharged) at much greater
rates in about 1-2 hours. An electric vehicle usually will be able to operate
for 1 to 2 hours before needing to be recharged.
Percentage of Available Capacity from a 100Ah Battery at different discharge
rates using different Peukert exponents
34
C/→
n
1
1.1
1.2
1.25
1.3
1.5
Discharge Rate in Amos
20
5
100
100
100
100
100
100
10
10
100
93
87
84
81
71
6.0
16.7
100
89
79
74
70
55
4
25
100
85
72
67
62
45
2
50
100
79
63
56
50
32
1.3
75
100
76
58
51
44
26
1
100
100
74
55
47
41
22
0.5
200
100
69
48
40
33
16
0.4
250
100
68
46
38
31
14
0.3
300
100
66
44
36
29
13
0.25
400
100
65
42
33
27
11
0.2
500
100
63
40
32
25
10
For example: A 100Ah battery with a Peukert exponent of 1.25 will deliver
on 47% of its capacity (47Ah) when supplying a 100A load or being
discharged at C/1 rate.
Anothere example: A 200Ah battery being discharged at 50A until fully
discharged (equivalent to a 25A discharge on a 100Ah battery) If the battery
delivered 72% (144Ah) the Peukert’s exponent would be 1.2
Let’s look at a more realistic application and comparision. The Cavalier EV
Conversion has a gel cell battery rated at (C/20) of 97.6 Ah (close to the
100Ah in chart). In real applications the vehicle will go about 50 miles or
have a run time 1-2 hrs. The C/1 rate is 64.5 Ah (measured) which
indicates Peukert exponent of about 1.15. Now, let’s say that I wanted to do
some drag racing and was setup to be able to pull a 500A draw (and that
batteries could deliver that), going to the chart you can see that the battery
is capable of delivering only about 50Ah. In terms of a fuel tank analogy,
your fuel tank shrinks as you pull fuel faster out of it!
Battery State of Charge (SOC) or depth of discharge (DOD)
These are ways to figure out how much more driving you can do before your
batteries are empty. Your EV “fuel gage” measures Watt-hours of energy.
Watt-hour counters can be programmed with battery capacity, Peukert’s
exponent, and other particular batteries characteristics. They then count
watt-hours and can display various information relating to the state of
charge of the battery pack, including remaining energy and thus range,
which is what the Link 10 meters do.
Other methods include direct voltage measurement, specific gravity
measurements, current measurements. All have some significant limitations
and all change over time particularly as the batteries get older.
1.)
Direct voltage measurement: This uses the voltage of the
battery cell as the basis for calculating SOC or the remaining
capacity. Results can vary widely depending on actual voltage level,
temperature, discharge rate and the age of the cell and
35
2.)
compensation for these factors must be provided to achieve a
reasonable accuracy. If you look at a graph of open circuit voltage
versus residual capacity, you will note for a high capacity Lead Acid
cell, the cell voltage diminishes in direct proportion to the remaining
capacity. Some batteries drop off faster than others which mean
you are losing power or speed as the battery discharges. Voltage is
not a good predictor of range left or of charge left, but it is good to
know when it is time to quit driving and recharge.
SOC from Specific Gravity (SG) Measurements - This is the
customary way of determining the charge condition of flooded lead
acid batteries. It depends on measuring changes in the weight of
the active chemicals. As the battery discharges the active
electrolyte, sulphuric acid, is consumed and the concentration of
the sulphuric acid in water is reduced. This in turn reduces the
specific gravity (SG) of the solution in direct proportion to the state
of charge. The actual SG of the electrolyte can therefore be used as
an indication of the state of charge of the battery. SG
measurements have traditionally been made using a suction type
hydrometer which is slow and inconvenient. Nowadays electronic
sensors which provide a digital measurement of the SG of the
electrolyte can be incorporated directly into the cells to give a
continuous reading of the battery condition. This technique of
determining the SOC is not normally suitable for other cell
chemistries, particularly sealed batteries. Again this is not a
predictor, but current status reading.
So what is the best way to implement a fuel gage? A gage that can
integrate the current draw over time with a Pueket’s constant is best to
predict energy used/left. But unlike your gasoline car, if you drive hard your
EV energy drops faster. Watch your fuel gage, always reset your trip
odometer each time you charge, and watch your foot on the accelerator
pedal. As you drive more and more you will become comfortable with the
range you can expect. The other instrument that can help you is the current
you are drawing (Link 10 has this as a display option). If I knew more about
the vehicle’s tachometer, I would convert this to be an ammeter so you
could tune your driving style to minimize current draws.
Final Words of “Wisdom”
The answer to 90% of the questions about EV’s can be answered
quite simply, “It’s the batteries, stupid.”
36
Chapter 4: EV Chargers for Conversion Vehicles
What are the requirements for a charger?
1. First question is on-board, off-board or maybe both. I believe the onboard charging option is mandatory due to limited range a conversion
will have, particular with lead acid. Off-board is very limiting. But a
low power on-board and a high power off-board may make sense, if
you can afford it and find them.
2. What power level? There are standards for three levels of charging for
the consumer.
a. Level 1 charger is 1kW and is good for 120VAC @ 15A household
circuit.
b. Level 2 charger is 3kW and is good for 240VAC @ 15A circuit
c. Level 3 Charger is 6kW and is good for 240VAC @ 30A dryer
circuit.
These are guidelines and you can really use anything you want, just
remember if you want to charge your batteries away from your house,
will there be a receptacle to plug into?
3. There are detailed Underwriters Lab specifications for chargers, and
SAE has them too. I would follow SAE because they were written
around automobiles and they reference the other standards.
4. A key issue with chargers is electrical isolation. What does this
mean and why is it important? The charger should be electrically
isolated from the vehicle chassis such that ground current from the
grounded chassis at any time while the vehicle is on charge or the
charger is connected to an off-board power supply does not exceed 5
mA. This minimizes potential shock when touching the vehicle. To test
this all exposed conductive surfaces of the charger and vehicle frame
should be evaluated. With the charger plugged into the wall, measure
current flow (leakage current) from the vehicle to the return and
ground circuit of the plug (this is the white wire in the cord and the
green wire. In 220 V, it is the while wire; the black and red carry
120V phases, and some 220V lines will also have a green ground)
5. Leakage current defined: “Leakage current” is a generic term applied
to any form of unwanted currents. “Leakage current” or more
accurately, “touch current” as it relates to electrical shock hazards is
the current that flows to ground through the human body due to
inadequate insulation or improper grounding between internal supplies
37
and accessible conductive parts. Since the human body’s reaction to
electrical shock depends on many variables, one of which is the
frequency of the current being experienced. Human body is less
sensitive to higher frequencies so sometimes the unit, Measurement
Indications Unit (MIU) is used to correct for frequency. But for
standard 60Hz current a 0.5 MIU is equivalent to 0.5 milliamps
(0.5mA) which is the same for DC currents. Burn hazards can occur at
70 mA and this is considered the safe limit to prevent leakage current
related electrical burns.
6. High voltage connections – there shall be no non-insulated connections
that could expose people to high voltage on the outside of the charger
(high voltage is defined as any voltage greater the 42.4V)
7. Weather protection – Chargers are usually mounted outside the vehicle
both for cooling of the electronics inside the charger and to prevent
occupants from accidentally touching high voltage or touching a high
temperature surface on the charger. This would mean that the
charger needs to be environmentally sealed. If the charger were to
overheat or fail and catch fire, the damage would be contained outside
the vehicle. The charger should not have ventilation holes that would
allow water to enter the charger, either in operation on the road (prior
to charging) or in stationary operation while plugged in for charging.
8. Wiring to the batteries and to the wall plug should have sufficient
insulation to prevent electrical shorting of the wires and should be wire
gauge sufficient to carry the charger input and output currents.
9. Input Power: the plug configuration should be compatible with
standard wall outlets, 120VAC or 220VAC including a ground circuit.
The charger should be able to handle from standard 60Hz to 50Hz
alternating current. Ground fault circuit interrupters (GFCI) are not
required.
10. Vehicle charger connections – the type, size and location of the point
of the vehicle should be described and identified. It should be
designed so that convenience is in mind for the operator. The outlet
or plug should accept common extension cords of proper gage based
on current and distance.
11. Vehicle shall be prevented from being driven with the key turned on
and the drive selector (gear shift) in forward or reverse while the
vehicle’s charge cord is attached. In addition:
38
a. Controller shall not initially energize with the charger plugged
into the wall.
Not directly related to the charger but important safety issues are:
b. Controller shall not initially energize to move the vehicle while
the vehicle is in other than neutral.
c. Controller shall not initially energize if there is a pre-existing
accelerator input.
12. Should be able to charge completely in less than 12 hrs
13. True power factor of 95% or greater and harmonic distortion rated at
≤ 20% (current at rated load). This is important from the standpoint
of the chargers effect on the utility grid and really is only applicable to
higher power charging stations. These goals are still good and should
be achieved even at lower charging power levels.
14. Charger should be fully automatic determining end of charge
conditions are met and transitioning into a mode that maintains the
main propulsion battery at a full state of charge while not overcharging
it, if continuously left on charge. The charger does not need to have
an on/off switch which is why it should be automatic. It is not
acceptable for the charger to need active adjustment, control and
monitoring by the end-user of the charger. This is a science-fair
project approach and not true automotive “plug and play” approach.
When people can adjust things (other than perhaps the initial set-up of
the charger), they have the potential of messing up the charger and
battery charger algorithms which could result in improper charging of
the batteries that could lead to more serious problems, such as
overcharging and releasing explosive hydrogen gas.
15. The charger should have over-load protection. This would be in the
form of a fuse or circuit breaker. Access for replacing or resetting
requires removal of the cover of the charger (be sure the charger is
unplugged and disconnected from the batteries before do this.
Understand why the overload circuit was tripped before resetting the
charger.
16. Operator visual information shall include lights or something to
indicate the status of the charger. The lights should indicate the
charger is plugged into an AC outlet. The lights should indicate when
39
the charger is charging and when it is complete. Having no lights is
not a good way to indicate the charger is finished.
17. Acceptable operating temperatures for the case: Per UL, the case and
surrounding parts should not exceed 140oF.
Final note: There are a large variety of chargers available for the conversion
market. Most of these “work” but most are not plug-and-play. Many are not
isolated, many require constant playing with adjustment, very few do any
battery pack management, many have exposed connectors, etc. At least I
have tried to tell what to look for, so whatever ever you buy, you now know
the consequences of your decision.
UPDATE: With Lithium ion batteries there has been a lot of work done to
develop Battery Management Systems (BMS). These complex systems are
designed to insure the batteries stay in balance and are not over charged or
over discharged. With some of the poor quality and inconsistent
performance from lower cost batteries, these BMS units have been the “fix”
for poor quality. The people who design them will never agree to test
systems with and without their BMS units which I find interesting.
I believe as the World gets to higher volume, automated assembly systems,
that batteries will become higher quality and more consistent in
performance. I believe the need to monitor on an individual cell basis will
stop and the BMS will be used to adjust primarily for temperature
differences in larger packs and to perform some higher level balancing need.
The key issue with Li batteries is whether the failure mode is open or
shorted? Lead acid almost always fails, open. Some Li chemistries can fail
shorted which can create a thermal hazard. Choose wisely if you go the Li
route.
40
Chapter 5: Drive Systems for EV Conversions
The drive system is defined as motor, controller, transmission, batteries, and
charger. The drive system is what makes an electric vehicle, drive
electrically. We cover many of these parts separately, so in this part of the
guide, we will talk about the motor and how the power gets to the wheels
and moves the car (usually a transmission system).
Our conversion is basically a plug-in battery electric vehicle (BEV). This is in
contrast to hybrid electric vehicles (HEV’s) which retain the ICE (Internal
Combustion Engine) and uses the ICE to propel the vehicle and charge the
batteries, while the electric motor can supplement the mechanical drive
system and capture regenerative braking. There are numerous types of
hybrids, but basically fall into two or three classes. Parallel hybrids use both
the ICE and electric motors to propel the vehicle. Series hybrids use only
the electric motor with batteries and the ICE is designed to run a generator
to charge the batteries when they require recharging. The generator system
is designed to generate enough power to run the vehicle continuously until it
runs out of fuel. Lastly there is a combination of the series and parallel
systems that functions in transition between the two. Toyota’s Synergy
Drive in the Prius is such a combination.
Fuel cell vehicles (FCV’s) are also electric vehicles where hydrogen is used as
a fuel to power a fuel cell which generates electricity to charge batteries or
super-capacitors and provide electrical power to the motor.
Motor choices for today
There are several types of motors, but the one that remains the most
common, available, and affordable is the series DC brushed motor. These
are good choice today but with time, we hope to see better technologies
become more affordable.
The list is (in increasing levels of efficiency):
1. Series DC brushed motor
2. Separately excited DC brushed motors
3. AC induction motors
4. Permanent magnet DC brushless motors
The development of the electric motor has provided us with one of the most
efficient and effective means of accomplishing work that man has ever seen.
Without electric motors, many aspects of our current civilization might not
have been possible. Electric motor principle is relatively simple in that it
converts electrical energy into mechanical energy. I will just cover some
41
basics and there is a lot more information available, but this will provide
some background and understanding of motor basics including magnetism,
DC motor theory, construction and components, basic DC motor
terminology, as well as define several different types of DC motors.
Magnetism
It is commonly known that magnets will attract various types of metal when
held in close proximity. The magnet does this because of a common force
called a "magnetic field". "Lines of Flux" typically help show a visual
representation of magnetic fields. The stronger the magnetic field, the more
lines of flux will be shown. Lines of flux are always drawn directionally to
shown the distinct movement from North pole to South pole.
Magnetic principle in an electric motor can be represented by visualizing a
permanent magnet and a simple electromagnet created with a single
winding and a small battery. Place the permanent magnet which has a
permanent and distinct North pole and South pole fixed and in close
proximity to the electromagnet wire coil . Run current through the
electromagnet to create a South pole and a North pole. The permanent
magnet will exert a magnetic field which with a little help to start the
electromagnet coil, will start to rotate. In magnetism, similar poles repel
each other and opposites attract. So, naturally through the laws of
magnetism, the permanent magnet wants to attract and repulse the wire’s
electromagnetic field. Once it starts turning, the force of attraction between
the unlike poles becomes strong enough to keep the magnetic field rotating.
Once stopped, the unlike poles line up, the rotor would normally stop
because of the magnetic attraction between them.
This is a very simple motor – two parts and a battery! Our explanation is
also simplistic of how a magnetic field causes an electric motor to turn, and
real life motors are much more complex, but the principle is the same.
42
AC vs. DC Magnetism
Reversing the magnetic polarity in electric motors varies in principle between
AC (Alternating Current) and DC (Direct Current) motors. With DC power,
the current always flows in one direction and with AC, the current flow
direction changes periodically. In the US, the most common form of AC
power is what flows through your house and is 120 VAC (Volts Alternating
Current) 60 Hz. This means that the current flow changes direction 120
times per second. This can also be called 60 Hertz AC. This is named after
Mr. Hertz, who first thought of AC current. I will not cover AC motors, but
typical simple AC motors run at some multiple of the 60 Hz switching
frequency. 60Hz is 60 cycles/per second or 3600 cycles/min. Many AC
motors run at 1800 rpm or 3600 rpm. I will leave AC motor theory at this
point. Lots of information is available for you to read else where.
DC Motor Theory
The first motors were called dynamos from the Greek word dynamis which
means power. "Motor" comes from the Latin word "motus" which means one
who imparts motion. The dynamo was not invented by one person, and was
a mass collaboration of many people, from many different places around the
world.
Motor Basic Principles
To change mechanical energy into electrical energy, i.e. a generator, you
need to move a conductor through a magnetic field. The opposite is also
true. If electrical energy (current flow) is applied to a conductor in a
magnetic field, a mechanical force and mechanical energy will be produced
as we did with our simple motor above.
43
DC Motor General Composition and Construction
Typical DC motor or generators are composed of basic components which
we'll define below: an armature, an air gap, poles, and a yoke which form
the magnetic circuit; an armature winding, a field winding, and a
commutator which form the electric circuit; and a frame, end bells, bearings,
brush supports and a shaft which provide mechanical support.
NetGain Technologies, Warp Motor
•
Armature Core or Stack: The armature is made up of thin magnetic
steel laminations stamped from sheet steel by a die. Slots are punched
in the laminations with another die. The laminations are welded,
riveted, bolted or bonded together. The armature is the central portion
of the motor which spins inside the field as represented by the
permanent magnet in our fist basic example earlier.
•
Armature Winding: The armature coil is the winding, which fits in the
armature slots and is eventually connected to the commutator. It
either generates or receives voltage depending on whether the unit is
a motor or a generator. The armature usually consists of wire, either
round or rectangular and is insulated from the armature core.
•
Field Poles: The poles are made from solid steel castings or from
laminations. At the air gap, the pole usually fans out into what is know
as a pole head or pole shoe. This is done to reduce the reluctance of
the air gap. Normally field poles are formed and placed on field pole
cores and then the whole assembly is mounted to the yoke.
44
•
Field Coils: The field coils are windings, which are located on the poles
and set up the magnetic fields in the machine. They also consist of
copper wire and are insulated from the poles. The field coils may either
be in shunt windings (in parallel with the armature winding) or series
windings (in series with the armature windings) or a combination of
both.
•
Yoke: The yoke is a circular steel ring, which supports the field, poles
mechanically and provides the necessary magnetic path between the
pole. The yoke can be solid or laminated. In DC units, the yoke also
serves as the frame.
•
Commutator: The commutator is the mechanical rectifier, which
changes the AC voltage of the conductors to DC voltage. It consists of
a number of segments normally equal to the number of slots. The
segments or commutator bars are made of silver bearing copper and
are separated from each other by mica insulation.
•
Brushes and Brush Holders: Brushes conduct the current from the
commutator to the external circuit. There are many types of brushes.
A brush holder is usually a metal box that is rectangular in shape The
brush holder usually has a spring to keep the brushes firmly in contact
with the commutator. Each brush usually has a flexible braided copper
shunt or pigtail which extends to the lead wires. The brush assembly is
often insulated from the frame and is made as a movable unit about
the commutator to allow for adjustment.
•
Frame, End Bells, Shaft, and Bearings: The frame and end bells (caps)
are usually steel, aluminum, or magnesium castings used to support
the basic machine parts. The armature is mounted to a steel shaft,
which is supported between two bearings. In many golf cart “3/4
motors”, the second bearing is often located inside the differential as
part of the differential input shaft.
Typical Golf Cart Motor ready
to attach to rear axle assembly
45
Armature Windings
Armature windings can be a very complex topic and I will leave that for you
to pursue further. One issue I do want to mention is a quality issue. A high
quality motor will be balanced and trued before assembly. This means the
armature air gap is consistent and uniform. The armature is sealed and
coated to prevent the windings from moving even at full rated speed. Lastly
the armature is balanced dynamically to run smooth with minimal vibration.
Many motor manufacturers to cut costs don’t balance their armatures,
hoping that by consistently winding them, they are close enough.
Sometimes this shows up as “noise” in the transmission, when in fact it is all
motor induced.
Field Windings
The field windings provide the excitation necessary to set up the magnetic
fields in the motor/generator. There are many types of field windings that be
used in either motors or generators. In addition to the following field winding
types, permanent magnet fields are also used on some DC applications (both
brushed and brushless).
•
Series Wound motors have the armature connected to the field in
series. To get high magnetic field, the field winding is large gauge wire
with just a few turns maybe as few as 6. Torque and speed control
are achieved by a throttle that varies the current flowing through the
field and the armature. Series motors offer very high starting torques
and good torque output per amp, but have generally poor speed
regulation. DC motors like all motors have high torque at low speed
and decreasing torque as the speed increases. In fact, it is current
that determines torque and voltage that controls speed. Speed of DC
series motors is generally limited to 6,000 rpms and below (there are
always exceptions). Series motors should be avoided in applications
where they might "lose their load" (stepping on the clutch and exciting
the throttle) because of their tendency to "run-away" and exceed max
rpm under no-load conditions. Never run a series wound motor in
a no-load situation. Series wound motors are the industry standard
in golf carts, industrial vehicles, and EV conversions. However the
industries are changing tremendously with newer technologies.
Separately excited motors are becoming the standard in golf carts
today and the motors were introduced in the mid-90's. AC motors are
starting to take over the industrial fork lift truck world due to higher
efficiencies and long run times.
46
•
Straight Shunt Wound motors, with the armature shunted across the
field, offers relatively flat speed characteristics. Combined with
controlled load speed, this provides good speed regulation over wide
load ranges. While the starting torque is somewhat lower than the
other DC winding types, shunt wound motors offer simplified control
for reversing service. This winding is connected in parallel with the
armature, Shunt windings usually consist of a large number of turns in
a small size. This is a good winding for reversing since it provides the
same amount or torque in both directions. Shunt wound motors often
have a rising speed characteristic with increased loads.
•
Separately Excited Winding used in DC brushed motors (SEPEX) are a
unique type of DC brushed motor with a separately excited armature
and stator windings. In a series motor, these windings are in series
and you will see large wires making both the stator and armature
windings. The motor works because of a magnetic field created by
passing current through these windings. This magnetic field is a
function of current and number of winding turns around the stator.
With a separately excited motor, the electronic controls can adjust the
current to the stator separately from the armature. This results in a
“variable speed/torque” motor. A SEPEX motor can have very high
start-up torque, but by field weakening with motor speed, also achieve
higher motor speeds (with less torque). SEPEX stator is made of much
small diameter wire but many more turns. SEPEX motors with their
controllers can provide regenerative braking easily and safely to the
motor. Unfortunately, there are not a lot of these motors and
controllers available in the sizes we need to do an EV conversion.
They are more expensive to make and consequently the industrial
world prefers cheaper is better. Separately excited motors are a type
of shunt winding and many modern golf carts and Low Speed Vehicles
use these.
•
Compound Wound (stabilized shunt) motors utilize a field winding in
series with the armature in addition to the shunt field to obtain a
compromise in performance between a series and shunt type motor.
This type offers a combination of good starting torque and speed
stability. This is also known as compound excitation. The series
winding can be designed as a starting series only or as a start and run
series.
•
Stabilized Shunt Winding is similar to the compound winding, this
winding consists of a shunt winding and a series winding. The series or
stabilizing winding has a fewer number of turns than the series
winding in a compound wound machine. It adds to the torque of one
47
direction of operation and subtracts in the reverse direction of
operation and in regeneration (half speed reverse and regenerative
braking).
AC induction motors
AC induction motors have the greatest potential because of the existing
production capability in the World today building AC motors. Literally
everything we own with an electric motor runs off of household AC current.
In industrialized countries it is estimated that 65% of the energy consumed
comes from operating AC motors. There are 100’s of millions of motors built
daily around the globe. These go from the very small to the very large in
size. There are many kinds of AC motors. Wikipedia.org is an easy source to
read to learn more. However, the 3-phase AC induction synchronous motor
is the one of choice for EV’s and electric drives. Almost all AC motors in use
daily are oversized, under-rated in order to be air cooled by ambient
conditions. Once we get into electric vehicle drive motors, cooling becomes
an issue as weight and size become increasingly important.
AC drive motors are starting to take a foothold in industrial electric vehicles,
like fork-lift trucks. The golf cart industry is starting to look at AC drives,
too. AC drives can be more efficient and reliable with lower maintenance
requirements than DC brushed motors. AC motors require a more
electronically complex controller, but with mass production and our
computer manufacturing capabilities, the prices will fall. The feature that I
find desirable is regenerative braking, which is very easy to do with an AC
motor.
Motor Selection
What you need to do is figure out your specifications for performance. These
would include:
1. How heavy is the vehicle with batteries and driver
2. How fast is top speed
3. How fast to acceleration 0-60 mph
4. What grades (how steep is the hill and how long is the accent) do you
need to climb and at what speed; typical specification is climb a 3%
grade at a sustainable 55 mph and climb a 6% at 45 mph with two 75
kg people starting at 50% State Of Charge (SOC).
5. How far to travel on a charge
48
•
•
•
If you
one.
If you
If you
needs
are trying to build a dragster, you need a different guide than this
want to build a race car, you need different guide than this one.
are building a road-worthy, use-it anytime, no excuse EV, it
to be, reliable and safe everyday, then this is your guide.
Motor curves: What they mean & What assumptions you can make
Every motor manufacture will provide motor performance curves. These
curves tell some of the story, but not necessarily all. Different companies
use different formats, but usually most of the information is there.
Typically the curves will show at a given voltage, what the torque (ft-lb or
Nm), motor speed (rpm), Amps, power output (hp or KW), and efficiency (%
of power out to power in).
49
Warp 9 @ 72 and 144 VDC
Torque, N-m,
Power, kW
100.0
80.0
N-m @72
60.0
N-m @144
40.0
kW @72VDC
20.0
kW @144VDC
0.0
0
2000
4000
6000
8000
rpm
Re-plot data at 72 VDC & 144 VDC see effect of voltage
50
For you with English units preference,
Warp 9 @ 72 & 144 VDC
Torque, ft-lb
Power, hp
80.0
ft-lb @72
60.0
ft-lb @144
40.0
hp @72VDC
20.0
hp @144VDC
0.0
0
2000
4000
6000
8000
RPM
Basically what happens is the higher voltage shifts the torque curve
proportional to speed (this is approximate, not exact because of other
factors). This increases the performance and power of the motor. The
torque curve remains flatter for longer period or to higher rpm’s. This
should greatly improve the driveability of the motor (this translates into less
shifting of gears). However, more power output does generate more heat
since you can operate at higher amps for longer periods of time. Nothing in
life comes for free.
Single ratio, Manual transmissions and clutches or Automatics
The first question is should I use a single gear reduction, manual
transmission with several gears, or can I use an automatic transmission?
You can use all of the above, but with qualifications.
Single ratio transmissions are used in several OEM EV applications; however
they use AC induction motors or DC brushless motors. All of these motors
are high rpm motors capable of 10,000 rpm or more. With 10,000 rpm’s to
work with you can set the motor’s high speed to some reasonable top speed
of the vehicle with a reasonable gear ratio. Since we are focused primarily
on DC brushed motors, they are limited to about 6,000 rpm. It is not
reasonable to expect a gas engine vehicle with 6000 rpm rev limit to work
effective with a single speed transmission and in fact we are seeing more
and more gears to improve gas engine operating efficiency. Same holds for
51
an electric motor, except the electric motor gets full torque at zero rpm,
rather than out near the rev limit. Some people don’t realize the excessive
strain that trying to run with a single ratio puts on a DC motor and
controller. The issue is complex because the single ratio requires a low
(numerical number) ratio, say 5:1. In a typical passenger car, this would
equate to 60-80 mph at 5000-6000 rpm (maybe 3rd gear). This would make
launch from a stop and acceleration up in speed require a lot of torque and
amps to happen. You would find that you quickly heat the motor and
controller up with the continuous high amps under high load. This is the
important point – heat – without the ability to change ratios you will find
that both the motor and controller will be at it limits in certain conditions.
One of the early questions was what are your expectations for gradability?
What kind of grades, at what speeds, for what distance or time do you
expect your EV conversion to handle without over heating and shutting
down? If you analyze this, I think you will see that multiple gear ratios is
the best way to deal with this. Also most motors have efficiency curves and
there are motor speeds and torques that are most efficient. With multiple
gear ratios, you can optimize your operating point for maximum efficiency. I
hope this will help some of you from going down a road fraught with
overheated motors and controllers. When in doubt, keep that transmission in
the loop.
What about the clutch? This depends on how you are going to drive your
EV. First of all you don’t need a foot operated clutch. Unlike your gas car,
when you come to a stop in an EV, the motor also stops. When you start,
you just step on the throttle and take off, no need to slip the clutch out so as
to not stall the gas motor. When it comes time to shift, you just shift gently
up in gear ratio. Going up in gears is not hard on the transmission because
you are shifting into a slower set of gear speeds. Down shifting can also be
done without a clutch, except if you are trying to do it fast and hard. The
transmission has synchronizers and if you pull gently and firmly and let the
synchronizers do their work, clutchless shifting works well.
The major issue with a clutch is exciting a series DC motor without load on it
(as in putting in the clutch and revving the motor). DON’T DO THIS!! A
series DC motor will go unstable and start to spin out of control, even after
you release the throttle (basically the armature circuit includes the
resistance of the field winding and the speed becomes roughly inversely
proportional to the current. If the load falls to a low value the speed
increases dramatically, which may be hazardous.) You have to put a load
back on quickly (release the clutch) before things get out of control.
Automatic transmissions can be used but have significant limitations. They
have a fluid clutch (torque converter) that basically under a 1000 rpm’s just
spins and does not transfer torque. So with an automatic transmission, you
52
have lost the use of the initial start-up torque and have just been spinning
the torque converter. Automatic transmissions are heavier, too. And as far
as shifting, the automatic transmission needs to be recalibrated since the
behavior of an electric motor is very different than a gas engine. Bottomline, it has been done and it does work, but it is less efficient and requires
more tinkering around. Some people will tell you, you can eliminate the
torque converter and connect the motor directly to the automatic
transmission and let the hydraulics of the automatic transmission do the
shifting for you. This should work but you have loss the torque converter
multiplier effect, which may not be as important with an electric drive. But
automatic transmission will shift through all the gears, which you may not
need or want. There is a lot of calibration work to make it feel right.
Mounting the motor to the transmission
This is a very critical element of the conversion. It needs to be done
correctly or the problems can be severe. Basically you have a transmission
that expects to be mounted to an engine block with a set of specific
mounting holes. The transmission expects the clutch and flywheel to be in
the proper position.
There are several companies out there that make these adaptors. I
recommend visiting www.ElectroAuto.com and read about their adaptors for
various motors and transmissions. They understand the issues and offer a
well designed and made assembly. I used one by ElectroAuto on my
Cavalier conversion in Chapter 9.
When mounting the motor to the manual transmission, you may ask why do
I need a clutch? Actually, you don’t. This begs the next question, Do I need
a clutch pedal? And again, you don’t. But there is not consensus on the
right way to do this. I like the idea of a lightweight flywheel with the clutch
plate. The clutch plate offers the electric motor a “soft” connection to the
transmission. The clutch can slip if the load is too high and it can provide a
small level of isolation when shifting. The springs in the clutch plate also
offer some shock isolation. The clutch pedal can go, unless you think it
could be a “safety item”, such that if there was a run-away failure mode of
the motor controller, you could put in the clutch to prevent the vehicle from
moving while you shut everything down. This is probably not a good reason
since you can use the vehicle brakes while you turn off the ignition switch as
well.
Mounting the motor/transmission assembly to the vehicle is the next issue.
Motor mounts are covered in more detail in Chapter 9. The main issue is
that you should be able to use or adapt the existing motor and transmission
53
mounts. If you have left the transmission in its original location, its mounts
should be fine. Transverse mounted motors are a little more complex since
the electric motor is smaller than the ICE it is replacing and it does not have
the mounting holes typical on an ICE block. However, the existing rubber
mounts should be adaptable to the electric motor. You may need to modify
the engine cross-member or build extensions to reach the motor mount
attaching holes. The original mounts were designed to take the many
different types of loadings engines are subjected to. These include wideopen throttle accelerations, rock cycles (shifting transmission back and forth
from forward to reverse as you try to rock the vehicle out of snow or mud),
rough road vibration & durability, crashworthiness integrity, and general
road durability. So if you can take advantage of all of this work and
validation, you are ahead of the curve. You can build your own system but
be careful since you will not be able to “test” it for long term reliability.
Some motor issues to have you consider. I have used a Warp 9 motor in my
Cavalier conversion (Chapter 9). These motors are very robust and have
dual sets of brushes for long life and high performance. The motors also
have an internal fan that not only helps to dissipate motor heat but also
clears out carbon dust from the bushes, thus preventing a flash-over that
could cause damage. The motors have a couple of items that are nice
features that you can used to improve life and carefree operation.
•
Warp motors have an internal thermal switch on the side that snaps
open (normally closed) when the internal motor temperature reaches a
high level (120oC) where you are endanger of burning out your motor.
The switch can be used for several things. You could wire your
contactor signal through this switch so that when the motor gets too
hot, the thermal switch opens which in turn opens the contactor and
the motor no longer can continue to run. Another use can be to turn
on a warning light on the dash, that tells you the motor is hot, slow
down and let it cool off. There may be options to use this signal to
send a message to the controller to reduce motor current, in order to
let the motor cool off.
•
Warp motors have added a brush wear sensor which once the brushes
have worn down there is a contact made to close a circuit that could
be used to turn on a “Service Soon” or “Brush Wear” light on the dash.
Most DC motors used in Electric Vehicle conversions are open frame with
vents for air to enter and exit and for access to replace brushes. How does
this open frame work in an on road EV Conversion and will there be
problems with water and dirt? This answer is one of trade-offs. First the
motors are forced air cooled; not sealed and water cooled, so it must be
54
open. OEM’s usually use sealed water cooled motors, so they don’t have this
problem. I have seen pictures of simple DC motors used in a farm
application totally covered in mud and still operating! These are not high
performance applications so do not let this happen in your conversion EV,
just understand that DC motors are very robust.
Relative to Motor Care and Maintenance:
• Protection from the elements is important. Utilize good design
concepts and materials to protect the motor from rain, snow, and ice
•
Design the motor mounting area to allow for good air flow. The motor
needs a continuous supply of clean fresh air to cool properly
•
Protect the motor from “dirty air” that may be used to cool it. Most
airborne grit will act as an abrasive, which will eventually cause harm
to the internal part of your motor. Dirty motors run hot when thick dirt
insulates the frame and clogged passages reduce cooling air flow. Heat
reduces insulation life and eventually can cause motor failure
•
Clean the brushes and commutator regularly from the dust/dirt that
occurs during normal operation. Do not use high pressure air to blow
this dirt out, you will only force dirt into the wrong areas and
potentially cause other problems
•
Regularly check connections, voltages, tolerances and alignment to
assure they are within normal specifications. If you hear noises from
the motor during operation, check this out further. Sometimes just
jacking the drive wheels off the ground and letting the motor turn over
slowly and listen for unusual noises can suggest the need for more
thorough maintenance and inspection
•
Always operate the motor within normal safety ranges in voltage,
amperage and RPM
•
Follow all safety rules
•
Your motor will take care of you, if you take care of it.
NHRA (National Hot Rod Assoc) has rules for drag racing that says the motor
needs a shield 360 degrees around to prevent parts and flames from
shooting out if the motor explodes during a race. We don’t expect that
problem ever to occur in our road car. But the design of a shield to keep the
elements out and allow clean air in is important. See Chapter 9 for what was
done on the Cavalier.
55
What makes a quality motor:
1. High efficiency design using low-loss laminations and welded or fused
commutator connections with a large commutator area. This helps to
lower heat losses and yield longer operating times per battery charge.
Efficiency should be reported on the motor curves
2. Durable construction where armature and field winds and assembly
are treated to lock in mechanical integrity (such as using resin
varnish) and provide permanent environmental protection
3. Quality parts and quality assembly means quality is controlled
throughout the manufacturing process and performance is confirmed
with testing before shipment
4. High quality, large brushes (maybe even dual brushes), in strong
housings with heavy duty, vibration & corrosion resistant brush
springs
5. Commutator construction that prevents lifting due to high
temperatures. The commutator is the major source for heat
generation in a DC brushed motor
6. High temperature rating, no less than Class H for an EV application.
Heat is the enemy of all electric/electronic equipment. The table
below summarizes common motor thermal ratings. The major concern
is life of the windings and its insulation
Thermal ratings of insulation classes
These are the highest allowable stator winding temperatures for long
insulation life. Temperatures are total, starting with a maximum ambient of
40° C
Insulation class
Maximum winding temperature, C
A
B*
F*
H
105°
130°
155°
180°
* Most common classes for industrial-duty motors.
7. Balancing of the completed armature at assembly. This is important
for motors operating at higher rpms and can lead to much quieter and
smoother operation in the vehicle
8. Sealed, high strength bearings with high temperature grease
56
9. High efficiency fans that provide the necessary cooling with lowest
power requirements
10. Light weight or light as possible
11. Industry standard size mounting patterns and shaft ends
12. Ability to connect a speed sensor to the motor
13. Uses standard industry parts (like brushes) for service.
Is Regenerative braking possible with a DC Series motor?
What is regenerative braking? Regenerative Braking or “regen” is a
technology when you take your foot off the accelerator pedal to stop, that
the motor becomes a generator and in generating electricity to charge your
batteries, offers resistance in the drive system which results in some
“braking-like” effort occurring. The generator converts kinetic energy of the
moving vehicle back into electrical potential energy in the batteries. In a
conventional vehicle, braking converts the kinetic energy of motion into heat
energy in the brakes. Regen will supplement your brake system and slow
your vehicle down and recharge your batteries. Regen can provide some
range extension (10%) depending on how much braking you need to do and
how much regen your system is set up to deliver. Regen is not well
understood in the non-automotive world. Regen sounds/is great and can
provide the effect of power brakes and deliver a more familiar slowing down
when your foot is off the accelerator pedal. However, too much regen can
cause serious handling and stability issues with a vehicle. Regen puts
braking effort into the wheels that the motor is set up to drive. It a FWD
vehicle, these are the front wheels and in a RWD vehicle, these are the rear
wheels. On a road surface that is either slippery (snow, grass, or loose
gravel or sand) or becomes slippery (first rain on the highway), too much
regen will lock up those wheels from turning a cause a changes that are not
expected. In a FWD vehicle, you can not steer the vehicle with the wheels
locked and in a RWD vehicle you can lose stability of the rear end that will
potential cause the rear end to loose control. Be careful with how you set
regen, it can cause vehicle handling issues you never before experienced or
expected.
But can you put in regen? Quoting the words of Otmar Ebenhoech the
designer and creator of the Zilla Controller from Café Electric: “In my
experience braking with a DC motor in a full size EV just destroys the
brushes and often destroys the commutator as well. This happens either in
57
regen or plug braking. That is why I no longer make regen controllers.
In my opinion the only real option for DC systems over 108V at this time is
adding a generator/alternator on the end of the motor.”
What he is referring to is the large inrush of current in regen back through
the brushes and causing a lot of arcing, heat generation and destruction of
your motor’s commutator. The concept of adding another motor/generator
on the end of the motor has been done but offers some complexity in that
you should have an electric clutch (like the compressor clutch on your ICE
air conditioner unit) so that it can be decoupled (with a switch) when you do
not need regen. If you truly want regen, than use a Separately Excited DC
motor, AC induction motor or DC brushless motor with regen setup in their
controllers.
58
Chapter 6: Automotive Electrical Systems for EV
Conversions
The 12V side is covered in Chapter 7 on Original ICE Vehicle and Its
Systems. I will cover some general issues that pertain to both low voltage
and high voltage.
First I want to cover the high voltage side. SAE recommends the all high
voltage (>44V) wiring be orange in color with the high voltage ground return
wires be orange with a black stripe. It is hard to find orange battery cabling
in small quantities. You can find orange sleeving and I would recommend
that if possible. As a last resort, use red color battery cables, but wrap
orange tape at the end points so it is noticeable.
Battery connection choices are many and each has pro’s and con’s. Many
people use the standard lead clamp connectors with bolt-on battery terminal
connections. Note: Positive and negative posts are different diameters to
error-proof connections.
Typical lead post battery
connector for terminal end
Crimp/solder on battery
cable post connector
59
Typical heavy duty
crimp/solder battery
cable connectors
Insulated boots for protection
from high voltage
For dual post batteries (stud for marine
and post for automotive (come in
black and red)
Deka battery with insulated covers & Radsok®
Some words of caution: Lead is not a great electrical conductor which is why
good quality terminal ends are plated copper. Also, you need to be sure you
have a contact area both in the terminal and in the surface area being
clamped down equal or greater than the cross sectional area of the cable.
For example if you think you need 1/0 AWG cable, this has a cross sectional
area of 83,000 circular mils or is 0.083 square inches. If you take a crosssection through the thinnest part of your connector, say it is ¾” wide, then
the thickness must be at least 0.11 inches to achieve same area as the wire
diameter. If you tighten it over a 3/8” stud (0.40” hole), then you need a
good surface contact area of a little more than ½” diameter (0.51” diameter)
to have the same area as the wire. If you do not have at least the same
areas, you are losing the advantage of the wire gauge you selected.
Sometimes this will show up as heat in your terminals. Be sure all contact
surfaces are flat and clean. Clean is a major problem if you use flooded lead
acid batteries, because when they gas and all of them do, there is a mist of
sulfuric acid that is released, which is corrosive. Corrosion will reduce
60
current flows by adding some resistance in all of your connections. How
much? Depends on lots of things, but be sure to keep them clean.
Now for my favorite connector; I have found a terminal end called a
Radsok® that is produced by Amphenol and is a great solution, but don’t
use these with flood batteries, because the sulfuric acid will destroy these
over time. They work great with any sealed battery. Here is the website:
http://www.amphenol-aerospace.com/new/radsok.asp?BU=2
I have used the 8mm Radsok® and it will carry 200A continuously, which is
more than enough. The wire gage I selected was 2 AWG, which will carry
180A continuously.
Alternative insulating boot for
a Radsok®
Radsok®, plastic cover and pin
The major advantage, in addition to the high current carrying capacity, is
that all battery connections CAN BE MADE WITHOUT mechanical tools, which
you can so easily drop and short out batteries. You can literally change your
batteries out without any metal tools. (This is also an example of applying
DFMEA – Design Failure Mode and Effects Analysis, to reduce the potential
failure mode of shorting batteries or getting exposed to high voltage.) Just
pull off the Radsoks® and remove the batteries. There are two varieties of
Radsoks®. One is plain, which I have used without any problems (shown
below), and the other is their SurLoc™ which is shown above and has a
locking clip at the top. You will need to have a machine shop do your pin
connectors to fit your battery studs. To keep height minimized, I actually
cut a ¼” off my studs to lower the pin. Watch when machining the pins,
Radsok® recommends a 30 micro-finish on the surface. If you want to do it
right, have them machined out of copper and then get them flash silver
plated. I have had no issues machining them out of brass with no plating.
61
The next issue is crimping terminal ends. This is pretty standard procedure,
but you need to understand that good crimps are not that easy to
accomplish unless you have the proper tools. I recommend that all hand
crimps be soldered for extra security (Please note that Radsok® will not
tolerate the heat from soldering, so use only a high quality mechanical
crimp.) For example, a proper (SAE defined) crimp on 16 AWG wire is for a
pull out strength of 27 lbs. and for a 12 AWG wire it is 54 lbs. These are
hard to do consistently and you don’t want bad crimps causing you phantom
problems, or even worst is having a high voltage wire come off of its crimp
and be lose somewhere.
Obviously battery cables are similar. SAE defines for cables larger than 8
AWG, a minimum pull out strength of 135 lbs. Since the Radsoks® are now
available with barrel crimps for standard wire gauges, you need a proper
tool to do these crimps consistently. Here is a picture of a proper tool that
has anvils/jaws for standard wire gauges. People have used the low cost,
beat it with a hammer tool, but it is difficult to insure consistency and I
would not recommend it. Some battery stores will make up cables and they
use industry standard crimping tools, which is what you want. Here is a
typical tool that I use.
Battery cable crimper tool
Radsok® & pin with crimp cable with
insulator boot and water pass-thru seal
62
Standard pin crimper for automotive
connectors like Amp Mate-N-Loc
Battery cable connectors & seals
Insulate all your terminal ends to be sure no one is exposed to high voltage
and to protect all your low voltage connections from shorting on something
unintentionally. Again, there should be no exposed high voltage that could
be touched without removing some bolted down or constrained cover.
As a good practice, route your high voltage cables away from existing low
voltage wiring. EMI (electro-magnetic interference) is reduced by keeping
the high voltage wiring away from other 12V wiring. EMI is a whole other
story, but do understand that we may have 50kW of power or more under
the hood of the car. A 50kW radio station is a pretty powerful radio station
and our wiring has similar potential to broadcast electro-magnetic energy
which can cause safety issues as well as radio interference. The OEM’s go to
unusual efforts to reduce EMI suspectability.
There will be a great deal of auxiliary connections to batteries – charger
wires, sensor wires, DC-DC wires, PTC heaters, MDS, contactor, fusing,
shunts, etc. All of these are high voltage connections and care should be
taken to use proper precautions to insulate and prevent electrical shock.
General Issues:
Tools needed
Standard 6-in-1 tool, cuts, crimps, strips,
cuts bolts, measures bolts & wire gages
63
Cable wire cutter
Multi-purpose linesman’s tool
Automatic wire stripper – very handy
You will need a soldering gun and rosin core solder (don’t use acid core
solder.) You will need the usual assortment of needle nose pliers, regular
pliers, wire cutters, and screw drivers.
If you are taking apart automotive style connectors you need special tools
that reach inside the connectors and release the pin that snap in place.
Pin extractor tools
When splicing connections use splice clip, then crimp and solder by applying
heat at center and let solder flow in from ends both sides. Use good crimp
tool with anvils for the various size wires you are using. Tape or put a piece
of shrink wrap on a wire before you crimp. It is best to solder all hand crimp
splices and terminals.
Strip to ends of the two wires, insert into clip and crimp. Solder with heat at
center and flow solder from ends (best) or heat at center underneath hole
and flow solder through wires
Or you can do it the harder way by
64
Strip the two ends of the wires lay
as shown
Twist from center to ends
In all cases tape or use a piece of
shrink wrap to cover completely
Solder as shown
Do not do splices without soldering. Do not use wire nuts, do not just twist
wires together without soldering, and do not cover twisted together with
tape to hold it together. These methods are not very reliable and will
eventually give you trouble.
Series hybrid generator for range extension
Some people have done this and it is very workable. The issue is adding a
generator (series hybrid) to charge the batteries while you are driving
beyond the limits of the stored energy. How big a generator? If you are
running at 300 Wh/mile at 60 mph, Then 300 Wh/mile * 60 mile/h = 18kW
(18,000W). This says at 18kW you are drawing @144V, 125A.
65
Chapter 7: Original ICE vehicle and its systems
All right, you have a vehicle to convert to an EV; Congratulations! Now, what
should you inspect, repair, fix, or save/discard for your “new” EV? Let’s
start:
Inspect/Repair/Fix/Save or Discard:
1. Manual transmission and clutch – all your power goes through the
transmission to drive your wheels. At some point, after you have
everything running electrically, have the transmission flushed and fill
with a lighter weight oil (weight has to do with viscosity or thickness of
the oil, the higher the number, the thicker.) Most people ignore their
maintenance on their manual transmissions, but the gears do wear
and sludge will build up and the shifting can get harder. Taking the
drain plug out and looking at the magnetic pickup on the plug will
show what is in your transmission. Normally manual transmissions
use SAE 90W gear oil that is so thick it comes in squeezable containers
to fill your transmissions. There are some lighter weight synthetic
manual transmission lubricants. BMW and Acura use one in their
transaxle applications. Redline Oil makes a product called MTL which is
70W80 GL-4 gear oil (SAE 5W30/10W30 engine oil viscosity) which is
designed for use in manual transmissions and transaxles. I have not
tried this but it “reads” very good. If you have a longitudinal mounted
engine and have a rear differential, the same thing applies, find lower
weight synthetic gear oil for rear differential.
2. Clutch plate – inspect and if it looks worn replace it. They are not very
expensive and now is the easy time to replace it.
3. Flywheel – you will need this to mount to your electric motor.
Flywheels are heavy to smooth out the gas engine through its firing
pulses. You need very little flywheel, all you need is a clutch surface.
The existing flywheel can be lightened significantly. You can take a
light cut on the clutch surface to clean it up and smooth it out.
Remove the ring gear for the starter motor – this is usually welded on
or heat shrunk on. Either grind the welds off or cut across the gear
and ring gear will fall off (as below.) I would not mess with the
thickness from the engine crankshaft mounting surface to the clutch
engagement surface. Changing this will require changes to the clutch
throw out distance; which is only an issue if you retain the clutch
pedal. Here is a picture before and after on a flywheel that was
lightened significantly. Thickness was reduced from ¾” to 3/8” taking
material off the back side. Be sure to balance the flywheel after
lightening it. Doing this statically is good enough; you can read about
how they balance model airplane propellers, and do it similarly.
66
Before
After
4. Half shafts (transverse front engine front wheel drive) or propeller
(prop) shaft (longitudinal engine, rear wheel drive.) Make sure your
half shaft boots are still in good condition and that the joints inside are
sealed with clean and proper grease. If in doubt (lots of miles?) get
new boots, clean out the old grease and re-grease with proper grease,
and reinstalled the new boots. New half shafts can be expensive. If
you have a prop shaft check out the U-joints on both ends. Make sure
they rotate freely and apply grease to all the rotating parts. These are
usually sealed for life, but new grease can’t hurt particularly if you can
get to the bearings.
5. Frame or uni-body structure – look out for heavy rust; this can weaken
the structure. When you get your donor vehicle check this out first. If
you can get a relatively clean vehicle, that is a better starting point
and will save you a lot of time with less prep work. Areas that show
rust should be brushed, sanded, or sand blasted to clean and then
repainted. Fenders or hoods can be replaced, but body side quarter
panels are much more difficult to fix for heavy rust.
6. Suspension – These need to be in good working order. They control
ride motion, rolling, steering, and braking.
a. Ride motion – This is normally shocks or struts. If worn, they
can be replaced. Since the vehicle is going to be heavier at curb
weight stiffer shocks are good to have.
b. Rolling – this has to do with wheel bearings. If they work
smoothly and revolve freely, use them. Well worn in bearings
are usually good, since they are “broken-in” and the seals are
67
not as tight as new bearings, so they turn easier. If there is
play (and there should be very little) (push and pull the tire
assembly bolted to the hub at 12:00 and 6:00 o’clock) then you
may need to adjust the bearings, if they are adjustable, or
replace if they are unitized bearings (non-serviceable). You don’t
want the bearings to have play in them because it can effect
other issues like rolling, steering, tracking and braking.
c. Suspension alignment – is critical for low rolling resistance.
When the vehicle is all put together and sits at expected curb
weight, have the alignment checked. Toe is the most critical.
Keep toe close to zero. Most vehicles have a little negative toe,
which improves on-center feel going down the road, but with an
EV you want to have as little rolling resistance as possible.
Negative toe puts the tires pointing inward toward each other,
so as you drive the tires scrub a little rolling down the road, a
small amount of negative toe sometimes results in zero toe
rolling down the road as the tires and front suspension geometry
cause a slight deflection of the tires outward. You never want
positive toe. Keep the caster to what the manufacturer
recommends and set camber to zero to again keep the tires
perpendicular to the road it is rolling on. If you hit a pot hole or
a curb recheck toe because these occurrences can cause the toe
to changing a lot. (You can check toe yourself with a helper by
buying a piece of 1” aluminum tube, 8’ long that is straight and
putting the tube horizontally on a block between the tube and
the wheel at wheel center. Then using a square place a mark on
Front
forward
A
B
B<A = toe in; set close to 0”
the ground below the outside of the tube against the wheel.
Then go the end of the tube and do this again. Now go to the other
side and repeat. Back the vehicle away and measure the distance
cross-car to the marks at wheel center (A) and at the end of the 8
68
foot tube (B). If the measurements are the same, you have zero
toe. If the front distance (B) is less than the distance at wheel
center (A), you have negative toe. If you want to adjust, loosen
the tie rods and screw them in or out to make the necessary
adjustment. If your steering wheel is straight, then you must
adjust the tie rods equally left and right to keep the wheel straight.
Be careful, since some cars use left and right hand threads on
opposite sides. (Mark everything with a Sharpie so you can always
return to where you started and know what you have changed.)
Go back and repeat the toe measuring procedure.
d. Steering – take the tire assembly (at 9:00 and 3:00 o’clock) and
push and pull; if there is play your tie rod joints may need to be
replaced. Also check to be sure the rack or integral steering
gear is tight to its mounting. Be sure to hold steering wheel
tight. Then there is the question of power steering. Do you
have manual or power steering? Most vehicles today have
power assisted steering to make it easier to steer, particularly
when the vehicle is not moving as in parking. If you think you
can live without power steering, try to get a manual rack for
your vehicle. If your vehicle has hydraulic power steering (most
commonly used system) then you have some options. 1.) You
can buy an electric motor and tie the hydraulic power steering
pump (take it off the gas engine you removed) to the motor.
You can put this on a switch, so you can run it only when you
need assist; this is a little weird and I would not recommend this
in anything but a play-toy EV. 2.) You can buy an electrohydraulic power steering pump that senses pressure in the lines
and when required turns on an integral pump with electric
motor. Several manufacturers have gone this route and you can
find these pumps on eBay (Toyota MR2, Mazda 3, etc). 3.) Find
an electric power steering (EPS) unit that will fit. More and
more manufacturers are switching to EPS since it saves on gas
consumption. In general option 1 consumes the most power
and option 3 the least.
e. Braking – you want these to work well and not offer any drag.
By drag I mean if you rotate the tire/wheel assembly, there
should be no scraping or rubbing noises from the brake pads on
the rotors; the wheel assembly should rotate freely. Most disc
brakes have some drag because the caliper pistons behind the
brake pads don’t retract fully after use, particularly as corrosion
occurs and time passes. Clean all the parts, grease the caliper
pins and any surfaces that rub against each other. For drum
brakes, clean all the surfaces and lubricate all the pivot points
and springs. Adjust the shoes so they release completely when
69
pressure is released. Adjust and clean braking system so that it
works and fully retracts when in the release position. Check the
cables for corrosion because sometimes this will cause the
parking brake to stick and drag.
f. Suspension arms, bushings and links – inspect, clean, paint over
any corrosion. Rubber bushings should last forever, but check
for cracks and chunks missing and if necessary replace them.
Check for damage (bent arms should be replaced).
g. Stabilizer bars – check end links and bushings and stab bar
mounting bushings. Replace anything that is worn out.
Standard bar should be fine. If you change weight distribution or
center of gravity height, you may want to change the diameter
of the stabilizer bar. Too small or too large can create handling
issues. Too small will allow more vehicle roll in turns and cause
understeer (plowing into turns). Larger bars are typically
available from lots of places. Be careful to not put larger bars in
the rear without adjusting front roll stiffness at the same time.
A too large a rear bar can cause oversteer and make the vehicle
feel squirrelly (this is a scientific terms for tendency of the rear
end to want to swap positions with the front end.) Changing to
stiffer springs has a similar effect as adding a stiffer stabilizer
bar particularly in turns.
7. Electrical system – Get a service manual and read through the
electrical section. If you decide to use a SLI (standard startinglighting-ignition) battery for your source for the 12(13.6) VDC
operating system, then everything should be all set to hook up the
battery, except you need a separate charger to plug in when you
charge the EV batteries. If you add a 12V DC-DC converter to your
battery pack to keep your SLI battery charged, then I ask why not
eliminate the SLI battery and just use a DC-DC converter for your 13.6
volt source? If you decide to use a DC-DC converter, then hook up the
positive output to where the SLI batter was connected (usually this is
a lead from the SLI battery to the underhood fuse block.) There is
more to understand than this. You need to match or control the 12V
power requirements that your vehicle needs in order to size your SLI
battery or your DC-DC converter properly. This is not that simple
since many gas engine vehicles use alternators that can put out 100A
or more. My 1997 Cavalier has an alternator with a rated output of
105A at 13.6 V or 1400W; the 2005 Cobalt which uses EPS has an
alternator that is rated at 115-135A depending on which engine. We
need to estimate the electrical parts power consumption and how will
we control that power level to a manageable level. Automotive people
talk about certain climate conditions that are worse case. Typically a
70
dark cold rainy winter’s night is a high power consumption load. Here
is a breakdown of those loads:
a. High beams – 65W x 2 = 130W
b. Tail lights and park lamps – 8W x4 = 32W
c. Side marker lamps & license plate lamps = 4W x 4 = 16W
d. AC system is on and blower motor is on HI – 240W for blower,
the AC clutch is about 50W and AC condenser fan is about
250W. Since we have eliminated the AC system we only have to
worry about the blower fan and the PTC heater element. This
would be 240W for the blower motors (and 1500W for the PTC
heater but the PTC runs directly off the batteries, and not off of
13.6VDC.)
e. Rear window defroster = 250W PULL THIS FUSE; it’s a luxury
we can do without.
f. Windshield wipers will use 140 W in HI
g. Instrument cluster with all of its lights – 2W X 5 =10W
h. Body and engine controller module – 10W x 2 = 20W
i. For a grand total of = 588W/13.6 = 43.2 A
j. Your standard SLI batteries which are typically 45Ah for 20 hr
discharge, will last about 2 hrs at 14A; you are drawing
considerably more in this situation. BEWARE!
k. You can simulate other more common driving situations and see
how you are doing.
l. Don’t undersize your SLI battery or your DC-DC converter, in
both case you will lose your 12V system, either with a dead
battery or blow a fuse in your DC-DC.
m. Another recommendation to help manage your power
consumption is to replace the blower motor speed control with a
solid state controller (PWM (pulse width modulation) controller).
The standard controller is a set of resistors in series with the
motor and it gets hot and consumes energy. Secondly, I would
replace all the major incandesant bulbs with LED’s bulbs since
they are 1/10 power at the same or brighter illumination.
8. The grounding of the 12V electrical system is another topic, but I
recommend not using the chassis for the ground on the vehicle’s
chassis/frame/body/structure. I believe that the 12V system should
be isolated from the chassis. For example, if there is a failure in the
DC-DC, you do not want your EV battery voltage to show up on the
frame. If you use one of your battery pack batteries as a 12V source
and lay one of you battery connections to the metal floor, you have
just shorted out your circuit and probably have a burnt ground wire
some where in your car. How do I isolate the 12V system grounds?
Depending on how old your donor vehicle is, you may have varying
degrees of work to isolate the 12V system. Most vehicles in the last
71
10 years have put ground wires on all electrical devices and have
brought those grounds to collection points on the body/frame. There
maybe a dozen of these collection points (see service manual). Take
these collection points off the vehicle and put insulated splices to a
new ground wire which you run to either your SLI battery or to the
ground of the DC-DC. Do this for all the ground collection points. Now
nothing is grounded to the vehicle’s chassis. Your “chassis ground” is
now on your SLI battery or your DC-DC. This is identical to what was
there originally except you don’t use the body structure as a ground
path.
That concludes how to inspect and deal with your donor vehicle. Again,
Safe is better than Sorry.
72
Chapter 8: Conversion Process
If you want to do it right you should have the following available to you:
1. Factory shop or service manual
2. Proper mechanical tools and equipment
a. Air tools like ½” impact wrench (sockets English & Metric), high
speed grinder, cut-off tool, 3/8” air ratchet
b. Electric Sawzall reciprocating saw
c. ½” drill (electric or air) and drill bits
d. screwdrivers and wrenches
e. hammers
f. crow bars and pry tools
g. Allen wrenches (English and metric)
h. Torx sockets & wrenches (male and female)
3. Proper electrical tools
a. Wire stripper
b. Terminal crimper
c. Larger crimper for battery cables
d. Soldering iron and rosin core solder
e. Volt amp meter
Nice to have tools:
1. milling machine
2. lathe
3. bandsaw (metal cutting)
4. bench grinder
5. sand blaster
6. MIG welder with enough power to do aluminum, too.
7. plasma cutter
8. hydraulic press
9. engine lift
10. transmission lift
11. cut off saw
12. air tools like an air saw, impact hammer, metal nibbler, sander,
etc.
13. low current meter
14. high voltage and current meter
15. You never have too many tools!
Process:
You have done your advanced packaging work and know where
everything will go, know what you need in terms of parts or systems, have
ordered them and have them waiting for you to start. There is a sample Bill
73
of Materials (BOM) as a guide in Appendix A. This is what I consider
necessary to do an “OEM” like conversion. It is more than what is required
to do a “hobbyist” conversion, but we want to tell how to do it right(safe) or
better, not just do it.
1. Batteries – build the tray, the battery hold downs, ventilation
system, covers as required, and all the cables to connect them
together including your main contactor, Master Disconnect Switch,
and controller fuse. If you use an E-Meter or similar device, you
need a 500A shunt (or more if you need more amps than that)
2. Motor – have your adaptor plate and all of its parts to interface
between your motor, transmission (gear box), your lightened
flywheel and clutch plate. Build your motor mount(s). Just a quick
word on motor mounts because I have seen this done poorly. The
original car used rubber mounts to hold the engine in position both
on the transmission and the engine. Unless you make all the
mounts rigid (I don’t recommend this) don’t have some rigid and
some in rubber, because you will cause undo stress on the rigid
mounts and they will eventually fatigue and fail. I would
recommend you mimic the original mounting system since it was
purposefully designed to isolate motor vibrations, take engine
torques and motor road induced vibrations. Follow your adaptor
manufacturer’s directions precisely since they have done this
before with other customers and they know what works and what
doesn’t. This is a very critical component that needs to be done
well, not just done quickly. All your motor torque goes through this
adapter and it must be tight and remains tight “forever” as well as
be perfectly aligned with your transmission input shaft. Most
motors are air cooled with an internal fan. DC brushed motors are
very robust and some water and dirt entry will not faze them a
whole lot. If you want to put a shield in front of it, that is good and
worth doing, just be sure you don’t block the all the air flow to the
motor. Cooling is critical.
3. Controller – this component needs to be water proof, not just water
resistant. The underhood environment gets very wet on a rainy
wet roads or salty in colder climates where salt is used on the
roads. Salt water can conduct electricity or current in certain
conditions. This leakage current should not exceed 0.5 mA. You
don’t want your controller to short out because of water entry.
That can be dangerous and expensive! I know that the Zilla is not
even water resistant and the Curtis controller is water resistant but
not water proof. Both can have problems if they get very wet.
Both have exposed high voltage contacts on the outside of the
controller which must be fixed in your application. There shall not
be exposed high voltage connectors, conductors, terminals, contact
74
4.
5.
6.
7.
blocks or devices of any type that create the potential for people to
be exposed to 50 volts or greater. This means you need to put
these devices in a sealed container that requires some specific
action to access. All the signal wiring to these devices should go
through a connector in the side wall of the container. These
connectors should be water sealed as well. Many people use
potentiometers for the throttle sensing. These are crude, will not
meet SAE requirements and are not as robust as the many
available electronic throttles used in many automobiles today.
Throttle by wire is becoming more and more common. These
pedals are tested to millions of cycles, are totally sealed, and have
redundancy built into the electronics. Both Curtis and Zilla have
options for electronic throttles. Take advantage and use these, the
pricing has come down tremendously as these are being made by
the millions, today.
Charger mounting, battery connections, and the charge port for
plugging into the wall. Most chargers generate heat when they are
operating. Place the charger so that it can naturally cool itself.
Again, all connections to the charger and batteries should not
expose people to high voltage. Good chargers have sealed
connections to the charger. The charge port and charger should
similarly not expose people to high voltage AC from the wall outlet
(this would typically be 120 or 240 VAC.) The charge port should
be located where it is convenient to use. Some chargers or
controllers sense when the charger is plugged into the wall and will
not let the electrical system activate when plugged in. This is a
good safety feature to have. If your charger can plug into a
number of different wall sockets, you should make up adaptor
cables to allow you to plug into as many as possible. When you
need a charge, you need a charge and don’t need excuses about
not being able to find a compatible outlet.
Electrical low and high voltage wiring must be done carefully and
correctly to insure reliability and safety from high voltage. Layout
a wiring schematic with all the features and components for both
low and high voltage.
Mount all of your accessories for your EV and then connect them
according to your schematic . Check and double check all your
wires and their routings.
Drive system 1st test. First are the batteries charged and ready to
go? Second, make sure the drive wheels are jack up off the
ground. Are critical support systems operational? If the controller
is water cooled, is the system filled and is the pump working.
Check your lights to be sure they are working, the brake lights,
turn signals, headlights, and tail lights. Make sure your MDS is ON.
75
Turn the ignition switch ON to activate the main contactor. When it
fires you should have power to your controller and motor. Gently
press the accelerator pedal and the motor should start to turn. Be
careful to not excite the motor without a load on it, or the motor
speed can start to run away. Be prepared to push the brake pedal
if this happens. If everything is working properly then only some
tweaking is needed. If your controller is programmable, hook up
your laptop and read all the parameters settings. Change those
that best suit your vehicle. If the motor does not turn over, you
need to determine why and correct it. Is the contactor firing? Is
the throttle controlling the speed of the motor? Does your
controller record and save trouble codes that you can look up? If
all is ok thus far, I suggest having someone new check the wiring
and make sure everything you thought you did right was done
right. Fresh eyes are a great resource since you are so familiar
with it, you might not be seeing what you actually did versus what
you planned to do.
8. Now take your vehicle out for its first test drive. Create a log of
miles at start and miles at end and Wh’s used. It is nice to have a
meter that will measure amps and Wh out of the wall and into the
batteries. Run the vehicle through its gears and decide which
gears work best for the vehicle operation. Typically, second gear
and fourth are all you probably need. As you climb hills, you may
want to use other gears. Using the tach and amps being pulled by
the motor, you will start to get a feeling of where the motor
operates most efficiently. Run the vehicle for 15 minutes, stop and
take a temperature measurement device like an infrared thermal
sensing gun. Read the motor temperature, the controller
temperature and any thing that appears to be hot. Sometimes
poorly made battery connections will get hot and these need to be
fixed to reduce resistance in the connection. If you get more
confidence about the running of the vehicle, start to run for the
range limits. How far will it go at 35, 45, 55, 65 mph? Time the
vehicle from zero to 60 mph; does it meet your projections. Find
some hills and start climbing them and watch your amps.
Periodically if you are drawing high amps, stop and measure
temperatures as above. Check your brakes and steering a make
sure they are working properly. Check your tires to make sure
they are properly filled to the highest pressure on the sidewall.
9. If you have new batteries, they will need to be cycled deeply
maybe 20 times to complete the battery formation process. As this
is done, the batteries get stronger and hold more energy and you
will go further.
10. You are now ready to tour the Galaxy in your EV conversion.
76
Chapter 9: Example of an “OEM-grade” conversion
This project started with a 1997 Chevrolet Cavalier. The car was found on
the street with a for sale sign for $500. The engine had a thrown a
connecting rod through the block. We offered $400 and he took it. We paid
a friend another $400 to pick it up and remove the gas engine, exhaust, fuel
system, radiators and condensers. He kept those parts for fixing up other
cars he repaired. We took the clutch, flywheel, and the motor mount and
torque strut and hydraulic power steering system.
$400 donor car w/ blown engine – 160k miles
Interior view
Rear View
Complete Engine Compartment
Engine Block with couple through holes
77
Manual Transmission without Engine
I did a complete weight and balance on the vehicle (actually I did this before
I bought the Cavalier to be sure it would make a good conversion.) To do
this safely, one must try to get the completed conversion car with
passengers and luggage at gas engine car’s rated GVW (Gross Vehicle
Weight) and not to exceed either the GVWF or GVWR (Grosse Vehicle Weight
Front or Rear axle.) One should attempt to keep the weight distribution
front to rear similar to original or closer to ideal 50%/50% weight
distribution. Many passenger cars, both front wheel drive (FWD) with
transverse engine or rear wheel drive (RWD) with longitudinal engine end up
with heavy front weight bias around 60/40 (front/rear). There is little the
manufacturers can do to alter this although most would like less weight on
front axle. Many manufacturers will add aluminum parts to the front end
(engine blocks & heads, hoods, fenders, bumpers, and even aluminum front
structure) and leave rear in steel.
So here is what I did; get basic data on your ICE (Internal Combustion
Engine) vehicle from data readily available on the Internet. Curb weight,
GVW, wheelbase, weight distribution at front and rear axles. You can even
find a similar car on a used car lot and open the driver’s door and look on
the door and you should see a label with GVW and GVWF & R. You then
need to estimate weights for the major parts being removed and EV parts
going back in. You can find weights for most of your EV parts on
manufacturer’s websites and retail seller’s of these parts.
Here is a quick weight estimate and then a weight and balance on my 97
Cavalier to illustrate the process and help you understand how to set this up.
Vehicle Weight Analysis - voltage to 144VDC
1997 Cavalier RS 2-door
Standard M/T weight as
Cavalier
received
LF
RF
Front
798
898
1696
LR
RR
Rear
539
406
945
Total
2641
System in Vehicle
Item
wt, lb
Total vehicle
GVW, GM defined
on door label
3600
5 passengers
840
luggage (GVWpassenger-curb
below)
119
max curb based
on GVW
2641
78
64%
36%
defined
calculated
calculated
weighed
est curb w/ AC
based on car as
weighed
2641
Vehicle Sys
HVAC
Body
Engine/
Transmission
Fuel & Exhaust
Fuel
Jack
Electrical
Radiator/Grill
Engine/
Transmission
Weight Removed
Item
A/C
remove rr ctr belts
Engine/Trans -MT
with shift controls
5sp M/T back in
Fuel & exhaust
Fuel, 14.1 gal
delete spare tire,
tools & jack
eng harness +
battery
radiator
misc removed heat shields,
power steering
lines, PS
pump&brkt, fuel
lines, HVAC-evap
& heater core
(includ'd in above),
air bags
coolant, eng/trans
oil, misc
subtotal=
wt, lb.
1.1
600.0
estimated
estimated
-170.0
120.0
estimated
estimated
86
38.0
calculated
estimated
50
estimated
40
40
estimated
estimated
20
estimated
825.1
Vehicle ready for
conversion
delete 1
passenger
delete cargo
capacity- no
luggage
1815.9
Motor, Warp 9
Controller, Zilla +
hair ball + fuse +
shunt + sealed box
and wiring
Zilla cooling sys,
heat exchanger,
resv, pump, DCAC
inverter, hoses,
coolant
156.0
38.0
168
119
EV conversion
parts
7.0
79
spec
spec & est
estimated
Charger(2) w/
DCDC
22.0
charger plugs,
socket, charge
port
5.0
Batteries 12 Deka 8G31
High voltage wiring
Body modifications
for batteries
Electronic ThrottleHEPI
Vacuum pump
hoses
Electric power
steering (column &
rack)
859.0
total add back EV
Parts=
Estimated New
curb=
Over original
curb=
add 4 pass
add luggage
new GVW
Over original
GVW=
1153.8
spec
estimated
spec
15.9
40
estimated
estimated
1.0
estimated
2.9
2.0
5.0
spec
estimated
estimated
2969.7
328.7
672.0
0.0
3641.7
41.7
Note: 42 lbs is close enough that with carbon fiber hoods, fenders and deck
lids, I could meet the GVW. Now the weight and balance to determine CG
(center of gravity) for weight distribution calculation:
CG calculation:
wheelbase,
in
Object
% front
% rear
front axle
mass
rear axle
mass
fuel tank
batteries
spare tire
batteries
104.1
weight, lb
64%
36%
1690
X, in
wt*X, lb-in
0
0
as weighed
as weighed
as weighed
951
104.1
98974
as weighed
357.9
78.5
28097
5
batteries
286.3
113.3
32443
4
batteries
80
underhood
deleted
items
remove rr ctr
belts
Engine out leave in MT
with shift
controls,
clutch ped
214.8
-18
-3866
-1.1
84
-92
-430.0
-6
2580
Fuel &
exhaust
Fuel, 15 gal
delete spare
tire, tools &
jack
-120.0
72
-8640
-86.0
-38.0
84
113
-7226
-4294
eng harness
+ battery
radiator
coolant,
eng/trans oil,
misc
-50.0
-16.6
830
-40.0
-20.0
-23.5
-12
940
240
misc removal
added items
Motor
Controller
Zilla cooling
sys
Charger &
port
High voltage
wiring
-40.0
50
-2000
156.0
39.0
7.0
-2
5
7
-312
195
49
FWD set-up
27.0
125
3375
15.9
73
1164
moved to
rear
more
connections
in rear
Body
modifications
for batteries,
bat tray rear
20.0
80
1600
fuel tank
area
bat tray mid
bat tray frt
HEPI
vacuum
pump
pump hoses
Master
Disconnect
switch +
main
contactor
EPS
10.0
10.0
1.0
2.9
113
-20
1130
-200
rear spare
front rad area
-16
-46
2.0
7.0
10
93
20
651
5.0
20
100
81
3
batteries
M/T back in
put it in rear
seat area
charge cord
reel
Totals=
20.0
2997.7
front weight=
rear weight=
113
2260
lbs
147972
1576.3
1421.4
lbs
lbs
not used but
cord on reel
in trunk
cg: (inches
rear of front
wheels) =
∑lb-in/total
lb.
%frt=
%rear=
49.4
53%
47%
Since I am close to the original weights for GVW (over by only 42 lbs) and
my weight distribution is better, my handling will be pretty good and over all
safety should be good. Note that I have items that I could consider to get
the 42 lbs out but the GVW for an automatic Cavalier is 3775 lbs, so I am
within the validated weight limits for the car and chassis. Remember that
GVM for a model line is curb weight, all standard options, all passengers,
and all luggage. Options like automatic and sun roof add beyond what our
vehicle was equipped with or spec’d out to be. Understanding these items
helps a converter do a safe conversion within the limits the vehicle was
designed for. One tool I use to estimate locations is to take a side view
picture (off the Internet for example) and lay a grid over it based on
knowing the wheelbase is 104.1.” With this grid, you can estimate where
parts are and know the approximated distance from the front wheel.
This model is where I ended, but it could be used early to start “playing”
with battery locations and see where the weight distribution goes as you
move them to different locations in the vehicle. Try to put batteries as
central to the vehicle structure as possible.
(The battery of choice for my EcoVElectric LSV vehicle and for my
Cavalier conversion was the Deka 8G31 gel cell sealed (maintenancefree) lead acid deep cycle marine battery. These are ideal for a standard
highway capable EV. However, if you are building a dragster or a racer,
you might want to consider a higher power battery. Deka’s can pull 550A
CCA at 32oF and Optima D31A Yellow top spiral wound are capable of
900A. But if you want longest cycle life for standard EV, I would
recommend the Deka’s in combination with the charger we will talk about
shortly.)
The vehicle structure is designed to protect the passengers and if the
batteries can be located in that same area, you will protect the batteries as
well in an accident. For most compact cars, they use the area outside the car
under the rear seat for the fuel tank; this is a good starting point. If you
can or could get batteries into the tunnel where the exhaust system ran, use
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that too. This is an ideal place for batteries (it was too narrow and shallow
in the Cavalier and I did not want to put the effort in to putting in my own
tunnel and redoing all the interfaces of parts and systems to a new tunnel.)
Then look at areas that typically do not crush much in an accident, like the
spare tire wheel (throw out the spare, jack and tools and save - 40 lbs).
Look at possible areas in the front engine compartment. The electric motor
is much smaller than your ICE, particularly when you eliminate exhaust
manifold and pipes, no accessory drive parts, like AC compressors and
alternators, no radiators or condensers or fans. All these parts limit
crushable space.
As you put batteries in front, there are a few things to understand and
avoid. If you look at the ICE version, you will note that there is a clear path
with no non-crushable objects in front of the brake master cylinder (you can
see this in the picture above.) In a severe accident (and they do happen)
you do not want parts to get stacked up between the object being hit and
the brake apply system. If parts do; they will push the brake system and
steering column back into your face and possibly break your neck or give
you a severe concussion or head injury. This is why there are crash
standards that limit steering column rearward motion in crashes. (To make
matters worse, with all our changes we decided to eliminate the air bags
since we have done so many things that might effect the crash pulse, but if
you wear your seat belts and sit at a proper distance from the steering
wheel, air bags offer minimal additional safety improvement.)
Keep your batteries as low as possible, but not so low that they are
the first thing that hits if the car bottoms out or you run over something that
might catch the pack. You can add protector skids if you are concerned it
might pick something up. If you do a pickup, I would avoid putting all the
batteries in the pickup bed, since that will raise the center of gravity (CG)
significantly and may affect handling of the truck. Putting them down lower
between the frame rails and outboard of the frame rails helps keep the CG
down.
Be careful where you put things. Some of this is covered in other
sections of the Guide, so go back and read them again. Again these are
guidelines, so if you don’t follow them you will at least be aware of the
potential consequences. Do It Right, Do It Safe; that is my
recommendation.
So let’s get to work now that there is a plan for building the EV
conversion. Let’s start with the rear battery positioning and mounting. We
started with building a mockup size battery out of Styrofoam since it is lot
easier to move around. We see how the four batteries position and what
modifications are needed. First picture shows how the forward corners of
the tub are cut out and how the rear area is removed to allow all four
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batteries to be positioned. Then we construct the battery support structure
from aluminum angle. The parts are pop riveted together and bolted to the
spare tire well. The four batteries are placed in location and two
support/retainer pieces are made out of wood using threaded rod to hold the
batteries from moving or falling out in a roll-over or crash. We will later
make a plastic cover so as to seal the outside of the car from the inside.
This open structure will naturally let the batteries cool if they get hot.
Lightweight Styrofoam mock-up battery
Build the battery support frame
Cut the tub
4 rear batteries sitting on tray
Next area is the fuel tank area. We use our mock up battery to mark the
five battery positions. We cut the rear seat floor out. Since seat belts
attach to this structure and have weaken it by removing a lot of it as well as
weakened the structure, we will add structure back in by welding a steel
tube across the underbody and attach it to the rear longitudinal rails on both
sides. Then we tack weld the floor structure to the tube to hold everything
together. The battery supports are made and pop riveted & bolted together.
Vertical supports are tied into the newly welded in cross car brace and to the
forward part of the floor. There is actually a box section in the floor in this
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area. We position the vertical height carefully since we have ground
clearance concerns from the bottom and seat position height from the top.
We know because of the height of the batteries, seating position will not be
as good as the original car but adequate. Again we make battery hold
pieces from plywood and bolted and secure the batteries. Later we will
finish the top cover and rear seat cushion.
Mark and cut the rear seat pnl
Build the frame to hold batteries
Note we have removed the center seat belts and will eliminate center rear
seat position and gain 170 lbs we can use in meeting GVW limits.
In the front we need only to locate 3 batteries. We place these with
understanding of crash considerations as seen below. We build supports
from the same aluminum angle and pop rivet and bolt together. Batteries
are placed on top and again plywood hold-downs are used to secure in place.
We use the strength of the radiator support cross-member to carry most of
the battery weight.
Next is the motor. I used a NetGain Technologies - Warp 9 motor which is a
very well made dual brushed series DC motor and will run it at 144 VDC.
(www.go-ev.com ) The curves shown in the motor section will give you an
idea of the performance expectations. Mounting the motor to the
transmission needs to be done right and I recommend a company like
Electro Automotive (www.electroauto.com) who uses a taper lock hub
adapter to tie the flywheel to the motor output shaft. There are other good
companies that do these adapters too. This is important if you want to keep
things tight and never have to worry about it. Read their words on their
website for more information. Many people do it the easy way with set
screws and this may work for a while, but can eventually give you problems.
Taper locks are often used in critical industrial applications and are very
secure. Electro Automotive carries an inventory of standard patterns for
many different transmissions. When using the tapered lock, follow the
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instructions carefully and it should stay tight forever. A set screw hub lock
can loosen over time causing the lost of the clutch pressure or rattling inside
the transmission and/or damage the transmission’s seals. The adaptor plate
has a spacer ring that put the motor in the right position for the
transmission and clutch. Assembly goes like this: Loosely assembly the hub
to motor shaft, attach the spacer ring to the motor, attach adapter plate to
spacer ring, slide the adaptor hub in and out to get the critical distance with
flywheel loosely attached (this distance is critical and measures how much
the flywheel mounting surface is inside the transmission case. It is easiest
to measure when the flywheel is still attached to the crankshaft – measure
the distance from rear face of engine block to the clutch surface on the
flywheel. Now slide the hub adaptor measuring from the mounting surface
on the adaptor plate the same flywheel clutch surface. Carefully take off the
flywheel and start tightening the tapered lock. Your may need to do this a
couple times to get it right. When right, tighten down the tapered lock hub.
Install flywheel and tighten and install the clutch plate housing and tighten.
Now you should be able to install the motor to the transmission using an
engine lift or shop crane. My adaptor plate had a small problem in that the
inner drive axle joint did not clear the adaptor plate. I marked this
interference and after a couple tries, I cut off the interference and it cleared
and slipped on the transmission shaft.
Motor with adaptor plate and spacer
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Taper lock hub fitting for flywheel
& clutch plate to mount to motor shaft
Lightened flywheel to attach to taper
lock motor shaft fitting
Clutch assembly with plate inside
to attach to flywheel
Ready for hub fitting and clutch/flywheel
(Note on bolts. Most cars in America since the 1970’s have Metric bolts but
some still retain English fasteners. There is a chart at:
http://www.boltdepot.com/fastener-information/Materials-and-Grades/BoltGrade-Chart.aspx which shows the specific markings for the different grades
of fasteners. Each bolt has a specific marking indicating the strength
required in that application. High strength fasteners allow more torque and
tightening power than lower grade fasteners. Always use the same grade
fastener or higher. In any structural application avoid standard off the shelf
bolts and nuts which typically do not have any head markings on them and
are typically Grade 2 material. These are good for your backyard swing sets
but not for any high load automotive applications. (If you try to torque to
manufacturer’s recommended torques you will twist them apart.)
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Motor mounts are another challenge. I used the existing transmissions
mounts as is. There are two on the transmission, one forward side and one
on rearward side. The engine mount on the original motor was designed to
provide good isolation and control of the motor under torque. I believe it is
worth while trying to use these. An electric motor does not need as much
isolation as an ICE but that should not create any real problems in a
conversion. With the motor attached to transmission and being supported
by the shop crane, I laid out and built a cardboard mockup to check out
design #1 for fitment and location, “installed” it, found some issues,
changed it, tried a new a version, and was satisfied. It was designed to be
made from standard steel flat stock. I laid out the pieces, cut them, tapped
the top mounting piece to match the holes in the original ICE that were
tapped, machined the precise hole pattern for the Warp 9 motor and welded
it together. The entire mount piece also incorporated the original torque
strut from the ICE. This is a very critical piece, particularly for a transverse
mounted engine. The single mount on the motor side can not react very
much torque which is why the strut was used. An electric motor will put out
lots of torque fast and needs this torque strut to control motor motion.
Engine mounting is a science in itself, particularly for transverse engines.
Longitudinal engines are much simpler to do, but again I would recommend
using the existing mounts where ever possible. All motor/transmission
mounts are in rubber. Obviously a gas engine has inherent roughness from
the fuel mixture exploding in the cylinders that an electric motor does not
have. Don’t mount the electric motor without some rubber isolation. The
rubber isolation allows the motor/transmission to share the support and
reaction loads. Mounting solid will cause roughness as the 200 lb. weight
tries to move around. Do not use some rubber mounts and some rigid
mounts because you will fail by fatigue the rigid mounts after a while as it
takes most of loads reacting the motion induced by the motor.
bottom view mount
installed with torque strut
Fabricated motor mount bracket
with speed sensor & OEM mount
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motor mount from top/outside
Motor mount from top/inside
The last item to cover is mounting the speed sensor. Zilla wants industry
standard 4 pulses per revolution speed sensor and Zolox is the
recommended choice for the motor speed sensor (from EVSource). They are
made to fit modern Advanced DC motors and Warp motors. The kit comes
with magnet to mount to end of the motor shaft, sensor, mounting screws,
and wire cable with waterproof connector. The issue is mounting it on the
motor in the car. There are concerns that need to be recognized. The first
is contamination and loss of the speed sensor function. The magnet picks up
anything metal floating around it which can cause problems with sensing.
Similarly, dirt, mud, water can cause issues too. There is a straight forward,
easy way to install & protect the sensor, so you will never have to worry
about it. Take a piece of tubing 1.5” diameter with .063” wall (1/16”) (16
gauge) & used this as the protective sleeve. The 1.5” fits into the motor end
opening and the other end fits over the Zolox external ring (1.375” OD). The
motor end gets a ring tack welded to provide a stop and to hold the sleeve in
position when inserted into the motor end-cap hole. I made a simple
aluminum plate to hold the speed sensor centered over a 1.5” hole. The key
tricky part is to make spacers of the right length to hold the sensor at the
right distance so that when the magnet is attached to the end of the motor
shaft the speed sensor on its plate and the sleeve are in proper position.
Pict of speed sensor kit
Sleeve w/ sensor on plate at bottom
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Pict of assembly w/ mtr mnt tubes
Same installed on mount (tubes to
be welded
Next step is to install the charger(s). I used two 72 V Delta-Q chargers with
integral DC-DC converters.
Rear view of QuiQ-dci shows Panel Mount DC Connectors (48V output green [72V
output is blue], 12V output black).
Go to www.delta-q.com and read more about these chargers. They are
available in the aftermarket. The chargers are totally environmentally sealed
and electrically isolated. They are very sophisticated having a multi stage
charge algorithm that starts with constant current bulk charging, then
switching to a constant voltage, followed by an equalization low current
charge. The chargers are very efficient and are air cooled. They are also
available with a remote light to tell status of the recharging operation. The
units have lights built in to tell status of the charger. The chargers are wired
to allow a number of options including sensing when the charger is plugged
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in to prevent driving off with the charger plug in to the wall. The DC-DC can
also be turned on/off with signals from the car. The chargers are 1kW
chargers and can operate on either 120VAC, 15A standard wall outlet or 240
VAC (will draw less at higher voltage and will not charge any faster)
automatically. Each charger will charge half of my 12 module battery string.
One will charge batteries 1-6 and the other will charge batteries 7-12. The
DC-DC converters are not isolated from each other and can not be used in
parallel. They can be used on independent 13.6VDC electrical circuits in the
vehicle as long as the grounds and 12+ are NOT shared with the other DCDC. In the Cavalier, one DC-DC powers the car’s entire electrical system
(with modifications, see discussion in previous chapters) except for the EPS.
The other DC-DC will power the EPS (peak – 50A) and electric heated seats
(Hi – 15A/pair) which are totally electrically separate from the vehicle’s main
electrical system. The chargers come with a number of standard battery
charge profiles including the Deka 8G31. These are selectable through the
set-up procedures. The DC-DC is 30A 13.6VDC (400W) continuous and 60A
for short bursts of < 3 seconds. It is internally fused and will shut down if
overloaded and will automatically reset when back to normal loads appear.
Please note that when you hook up the chargers to the batteries, the DCDC is alive and generating 13.6 VDC on two of its output wires so don’t let
these short out together or to the car. Tape them to isolate them until you
get everything hooked up.
I decided, for convenience to mount the two chargers in the trunk area. I
did this so I could see the lights on the chargers. I learned about the
remote lights after I had received the chargers and had originally planed to
mount them underneath the floor where they are currently mounted. I only
wanted one charge cord, so I wired the AC input cords together through an
electrical box. My experience with these chargers is that they draw less than
10A max, so a 120VAC – 20A circuit should work adequately. The 120VAC 20A plug is not as common as the 15A plug but they exist in many places
and probably your garage in wired for 20A but only has a 15A outlet, this is
easily changed but be sure it is on a 20A circuit breaker. The picture below
shows the different outlets as well as the 15A – 250VAC and 50A – 240 VAC.
120VAC – 15/20A
250VAC – 15A Dryer outlet
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250VAC – 50A
The only issue I need to watch out for is the cooling for the chargers. These
chargers naturally cool themselves with fresh air flow over the cooling fins
on the sides of the chargers. If I find an issue, than I need to move cool air
over the fins. This could be done with a small pair of 120VAC cooling fans.
Pict of charger in back
pict of charger Junction box
Picture of charge port
Overall view of charge sys
pict of cord and adaptor to 20A 240VAC
Pict of adaptor to 50A 240VAC
These chargers are isolated from each other. However it is good practice to
break your high voltage pack into 2 smaller packs. We installed our Master
Disconnect Switch (MDS) at the middle of the pack. Both halves are 72VDC
instead of one side being 144 VDC and the “other” side being 0 VDC. This
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offers potentially a little additional safety when doing service work. Besides
that, this is also sensible, logical, and good place for the MDS. Here is a
picture of the MDS box to be located in the middle rear seating position. In
this example the MDS I choose was a Marine Blue Sea Systems switch.
While it is only rated at 48VDC (because that is all they have tested it to and
they do think it is capable of higher voltages but UL testing is expensive and
this is all the boat industry needs), it is capable of accepting 1750A inrush,
350A continuous and looks like a “MDS.”
http://bluesea.com/category/1/products/9003e
I use only one Main contactor located before the controller and it is an
Albright SW-200
Albright model SW-200B SPNO Contactor with Magnetic Blowouts, 120 VDC, 250
amps continuous, 360 amps max, 12 VDC coil.
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These Curtis/Albright contactors use silver cadmium oxide contact material, which
is able to withstand burning and is extremely resistant to welding. Magnetic
blowouts allow rupturing of high currents at high voltage. The SW200 will handle up
to 120 VDC, 250 amps continuous, 360 amps intermittent, and rupture 1500 amps.
Here are pictures of installation of the MDS and Main Contactor in their
sealed boxes (why sealed? How many times have you spilled your
Coke/coffee in the back seat? You don’t want to short out your car or
electrocute your passengers with such an accident.) The main contactor is
in its own separate sealed box because in it located in the motor
compartment and gets full exposure to outside climate conditions.
MDS in sealed box as seen when opened
MDS switch installed in mid-pack
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Master Disconnect Switch in box
Contactor box on front upper tie bar
Main contactor in junction box
Close up of sealed circular connector
Lastly, let’s install the controller. I choose the Zilla 1K for several reasons.
First and most importantly, the Zilla is programmable and you can do it.
The Zilla also can output data on the system to a laptop computer and
create diagnostic codes to help trouble shoot issues that may develop. The
Zilla’s intelligence is well thought out and useful for road-worthy EV
conversions. You can set voltage limits to protect your batteries and current
limits to squeak out maximum efficiencies. You should buy it with the Poption that will accept an electronic accelerator pedal (highly recommend).
It has a number of safety checks it can perform for additional safety, won’t
start if foot on accelerator pedal or vehicle is plugged in for charging, etc. It
will drive a tach off the motor speed sensor and send signals to your dash to
turn lights on about battery voltage limits you set. It even has a “valet
switch” to limit current when switch is closed (we will show you how we use
it to create a highway efficiency limit current to maximize our range.) And
Zilla promises there is more to come. Zilla is also water cooled which is
probably more critical at 1000A than at 200A but that does add critical
reliability to the electronics whose life is directly related to temperature (less
heat is good!).
But the Zilla was designed for “hobbyists,” not “automotive engineers.” As a
result neither the Zilla nor the hairball are water sealed. Get them wet and
you risk having serious problems (mostly expensive problems and I don’t
know if there are potential safety issues that could occur, too.) But this is
fixable. We recommend and used a standard plastic sealed enclosure box (I
got on eBay) and mounted everything inside and used sealed connectors for
all the wires and pipes going through the case. All the wires to the hairball
are connected through a sealed circular multi-pin connector (there are many
brands out there that do this, see Mouser Electronics Catalog for some.) All
the battery cables go through sealed fittings to insure water tightness. Here
are pictures of what was done. Inside the enclosure box is the Zilla, hairball,
500A current shunt for E-meter, prescaler for E-meter, 500A fast blow fuse,
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and the coolant pipes. The box is labeled “HIGH VOLTAGE” and can be
locked to prevent accidental exposure to high voltage. The pictures below
show what was done. The support for the Power Electronic Module (PEM)
was a simple piece of aluminum tube mounted cross car to support it and a
brace in the back to the dash panel to provide stiffness and stability.
Pict of box 14 x 12 x 6
Lower mounting plate with parts on it
Pass through front w/ circular connector
Zilla parts mounted inside ready for wires
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Pass through rear w/pipes
All wired up with e-meter voltage
pre-scaler
Supports to unit
PEM unit from outside
Cooling reservoir with pump inside
Submersible pump inside
I used the CafeElectric recommended pump which seemed reasonable ($)
and low power. You do not want a high pressure pump. MAXI-JET 1200 is a
submersible pump that is available at aquarium stores or on-line. It requires
120 VAC which is easily made with a simple 12V to 120 VAC inverter. The
pump operates at 20W and provides 2.5 psi (less than 15 allowable) and a
flow rate of 4.9 gpm (more than 2 gpm minimum.)
UPDATE: http://manzanitamicro.com/ Is now building the Zilla Controller.
CafeElectric is still around.
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Simple inverter to connect to 12V
PEM Circular connector (not filled)
HEPI pedal installed with drip loop
HEPI pedal installed
HEPI is Hall Effect Pedal Input and is an electronic throttle and meets
automotive industrial standards which mean they are sealed and
contactorless and are tested for millions of life cycles. They will work worryfree forever if installed properly. No one should be using potentiometers
anymore since they were a very crude “quick fix” created before the industry
started to move to electronic pedals. Accelerator pedal-by-wire is now very
common in modern automobiles and is the only way to go. The Zilla
provided HEPI is good and comes with the cable and connector to the pedal.
It must pass through the dash and you should use a tight fitting grommet to
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seal moisture out of the passenger compartment and prevent the sheet
metal from cutting the cable where it passes through. Be sure to put a “drip
loop” inside on the cable routing. This prevents water, should it get through
the dash seals (and it will) from running down the cable and into the pedal
connector and possibly getting inside and causing problems. The drip loop
provides a low point where the drip will form and drop harmlessly to the
floor. OEM’s use these often because they have been burned by warranty
claims over and over with these potential leaks.
My set-up parameters for the Zilla are contained in Appendix B. To extend
range and be reasonable for a road car, I set max current limit to 350A. At
144VDC x 350A = 50kW or 68hp! This is more than enough. To achieve my
goal of 200Wh/mile, the vehicle must be capable of running at 69A =
(10000Wh/144V).
UPDATE: There is a setting to cut off power if vehicle speed is zero. Don’t
use this because the Zilla was not reading the speed signal and keep
shutting off the controller at 10 mph. Changed this and Cav worked great.
Other item is the HVAC which donated its heat exchanger for the Zilla. This
unit was replaced with a PTC heater that will run on 144VDC (note use of
high voltage orange power wires) and puts out 1500W of heat with the
blower on HIGH. There are some pictures of what was done. Note: I live in
Michigan and winters do get cold and this is an important feature both for
safety (keeping windshield clear) and comfort. The HVAC unit was removed
to install the PTC heater and this required the whole dash to be taken apart
and removed. This was another immense task and I highly recommend
using the Service Manual and take lots of pictures as you take it apart. Also
label all the screws and where they go. As I took the unit apart, I also
removed the evaporator and got rid of that extra weight, too. I sealed the
holes for the tubing and hoses that enter the unit through the front of dash.
PTC’s are nice in that they self-regulate. By this, they will change resistance
to limit the maximum current or heat generated. The most heat is
generated when the blower is on High and maximum heat is removed. To
switch the PTC on or off, I used the AC switch on the HVAC control panel.
You need to wire the heater so two items must be ON in order to send power
to the PTC. The heater switch must be ON and the Blower/Fan control must
be ON. The heater switch needs to go through a high current, high voltage
relay. The nice result of doing this is that all the HVAC functions will work
(except for AC) just as before, but remember this consumes a lot of energy
and that is also range. Use it sparingly because you have no waste heat like
your ICE and all the energy comes from your batteries.
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Pict of PTC heater installed
Pict of PTC power relay outside
Picture of HVAC unit in total from outside
Control Pnl w/ mods for PWM
UPDATE: We never got the heaters to work. It is probably a wiring error but
time never allowed us to solve this.
One item that I also changed to reduce my blower motor power needs was
to add a simple solid state 12V PWM Motor controller for blower speed. This
was a kit available on eBay (<$17) (www.electronic-light.com) and was
installed into the circuit instead of using the multi-resistor element which
generates a lot of heat/power except on HI. This is a significant power saver
if you plan to use the blower and/or heater. It is capable of 20A which is
just enough to cover the 18A or so that a blower motor needs.
This pot mounts on HVAC control in place of the fan
switch and the unit shown mounts remotely to it.
Actual size is 2” x 2” x 1.5”
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The motor control 12V input & ground & motor
outputs are here & are integrated into current
wiring
HVAC control panel PWM pot Rear View
UPDATE: The PWM never worked so we bought an assembled PCM unit from
eBay from China and adapted it. It works but speed control is really poor.
Good idea just poorly executed.
The other recommendation I have is to add electric heated seats (again easy
to buy on eBay). Heated seats are not a “luxury item” in an electric car.
They are actually very efficient both in power needs and heating your body.
They typically draw about 40-70W each and all the heat goes into your butt
and back relatively quickly. When installing be sure to put a power ON/OFF
switch and relay that goes through your ignition ON/OFF switch for power.
You don’t want to leave these ON when the vehicle is not being used.
I used 2 sets switches. One turns
the power to heated seats on and
off. The other 2 control the power
to each seat, both hi and low
Pict electric heated seats
pict of Heated Seat switch on dash
Electric Power Steering (EPS) and its installation (OMG!). I believe that we
will see more and more vehicles being equipped with EPS over the next 5
years rather than engine driven hydraulic power steering that has been
standard for over 40 years. (Chrysler Corporation introduced the first
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commercially available hydraulic power steering system on the 1951 Chrysler
Imperial under the name Hydraguide.) EPS has the main advantage in that it
only requires power when it is needed and only to the amount it is needed.
EPS offers improved fuel economy by maybe 3-5%. It is much simpler to
design into a vehicle and assemble at the factory. In lighter passenger cars
it is done with an electric motor on the steering column shaft, see below. In
larger cars the motor is being incorporated into the steering rack.
Cav(below) vs Cobalt steering column
Cobalt EPS(left) vs Cav
Cobalt rack top – Cav rack bottom Note Cobalt vertical bolt vs Cav horizontal
I used a 2006 Chevrolet Cobalt EPS system thinking it would naturally fit
into its earlier brother the Cavalier. Pictures above show similarities but
differences. EPS uses a manual type steering rack so you need to use the
complete system. Again the parts were available on eBay and at reasonable
prices. But having gone through this effort and tracked the time spent I
would never, never, never do this again. I would recommend that you start
either with a car with EPS (like Cobalt) or simply buy a used electrohydraulic power steering pump, adapt this and use it. EHPS uses an electric
motor and a pump that your hook into your existing power steering system.
EHPS basically replaces your ICE driven power steering pump. I have not
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done this so I can not speak from experience, but in theory the
pump/electric motor come on only when you need assist and the pressure
drops. You can find these and other pumps on eBay or the Internet,
including units designed for hot rods and custom cars. There are others that
hook up electric motors to drive the original hydraulic pump but the
mechanism to achieve high efficiency and power assist is difficult to do
“production-like”. Putting a switch to turn the motor on/off when you
want/do want assist is not production like.
UPDATE: To get the unit to function we had to go to a salvage yard to buy
the connector to the EPS unit. Our thought was to only apply the 12V signal
required to recognize the vehicle had power on. The CAN signals were not
available and we thought the default failure mode would be modest assist or
even read the torque sensor and use that to assist the steering. In default
failure mode, the assist is almost zero! EPS is totally worthless to assist
when vehicle is still. We contacted the supplier of the unit but they were not
interested in helping us with the default settings.
The last chassis item is the electric vacuum pump. I choose one that MES
makes that is quieter than many other brands. The vacuum pump is shown
mounted in the old battery tray position and is connected to the original
brake booster. The unit senses vacuum and only comes on when vacuum is
needed. I have started without any additional reservoir. My HVAC unit also
uses vacuum to actuate the various doors and flaps for the different
selectable modes (and has its own small reservoir.) My thought is that the
ICE did not need an extra reservoir and when the engine shuts off, so does
the vacuum source. The boosters are normally sized to be able to provide a
couple power assisted stops before all vacuum is lost. So will an additional
reservoir save anything? We will test this out and see where we go, but you
should not need one.
12VDC input power terminal (input
from original battery)
Original vacuum booster
Original ABS module
Vacuum pump
12VDC power ground (in
place of battery’s chassis ground)
MES vacuum pump
103
Here are a few miscellaneous items. I disconnected (pulled the fuse) for the
rear window defogger. This is a luxury item and we did without them for
many, many years about 20 years ago. They would overload my DC-DC
converter. Understand that the ICE vehicle has an engine driven alternator
that is rated at about 125A. You don’t have that power available if you want
any range at all.
I also disconnected my Day Time Running Lamps, so that I use my head
lights only when I want them ON. Again, an EV does not have any extra
power to waste.
Similarly, I changed out all my exterior lamps to LED’s to save 90% of the
energy over incandescent bulbs. Unfortunately, head lamps are only now
starting to switch to LED’s so the head lamps remained the same. High
Intensity Discharge Lamps (HID) are used on the Toyota Prius because they
require about 35% less energy, but they are very expensive (kits run around
$400-$500.) Your choice, but I would expect the prices will continue to fall
as more and more vehicles need the extra efficiency they provide.
For instrumentation, I ordered a simple VDO tach that will work with the
Zilla’s (and speed sensor’s) 4 pulse per revolution. I could not figure out
how to use this signal as an input into the Cavalier’s engine controller which
reads the engine crank sensor (7 pulses plus a check pulse per rev?) and
sends signals that eventually get to the original tach. Here is a picture of
installation.
UPDATE: We either burned the Tach up or it did not recognize the Zilla’s
signals?
I also had an older E-Meter (now Xantrex Link 10) but needed a pre-scaler
for the 144 V system. All the parts for operating and sensing were built into
the PEM, so that is where the e-Meter is driven from. The meter is an ideal
State of Charge instrument that can also show Battery Voltage and Battery
Amps coming out of the battery. This is not quite true, since my DC-DC’s
draw their power from my two “half packs.” Not all power being drawn from
the batteries returns through the last battery ground at the Zilla where the
shunt is located. The e-Meter can also track Ah, but this too is messed up
by charging the two “half packs” separately and independently.
104
E-Meter (old & used)
Tachometer
Lastly, I built my own battery voltage monitor. This allows me to monitor
each battery, each half pack, and total pack voltage. It requires a 20
positions or so, rotary switch (double pole). I used a brass washer under
each Radsok so by adding quick connect to the washer I could easily attach
a lead. Then running a small gage sensing wire from each to my monitor,
allows me to rotate the rotary switch to monitor the batteries. For the
meter, I used a low cost, low end digital volt meter and directly wired it to
the “common” position on the rotary switch (one pole is the positive side and
the other is the negative side.)
Battery voltage monitor
Battery voltage monitor RearView
Under my Radsok was a brass
washer with a spade connector. The
leads from the voltage monitor
connected to the spade connector
I just stuffed the whole unit into
glove box with enough wire in the
leads to be able to pull out and read.
pict of battery posts
Pict of installation in glove box
There is another critically important item is low rolling resistance tires (LRR).
Through some investigation, I identified that the Cavalier uses the same size
tire that the Honda Civic Hybrid uses and that this data was published on the
Internet through the Transportation Research Board of the National
105
Academies. The report is not current accessible since there has been lot of
controversy over tire rolling resistance as a piece of data that the public
should have access to when purchasing tires and that the tire companies
should provide. Rolling resistance is a key issue for EV’s. It was pointed out
earlier in this guide, but what you want to be sure when you buy tires that
the OEM’s claim to be low rolling resistance is that you get “OE tires” not
just the same brand and size available in aftermarket stores. Ask for the
“Article number” for the OE tire (and compare that to the standard tire’s
“Article number” the store offers...it must be different because aftermarket
tires are compounded differently than OE tires. It is impossible to get rolling
resistance numbers from the tire companies. Only the OEM’s have this data,
unfortunately. But this may change since LRR tires effects fuel economy and
fuel economy affects our Nation’s dependence on Foreign Oil and the
consumer should be able to buy LRR tires through competitive shopping.
Low Rolling Resistance tires
Tire on car
Some updates. I had a short in the Engine Control Module, so I pulled the
fuse to it. The only reason I wanted to keep it was to read the transmission
speed sensor to drive the original speedometer. I will now add a simple
speed sensor off the half shaft (like a bike or motorcycle speedo with a
magnetic pickup.) a drive a LCD display.
We had some problems with a short in the 12V system and found that one of
the pins in the circular connector to the Zilla box was breaking
intermittently. Fixed this and all should be good.
And we are now done!
OBSERVATIONS ANR SECOND THOUGHTS
1.) We killed the batteries because the engine control module had a
short in it. We could not afford another set of batteries so we
reused my EcoVElectric used batteries. We never really had the
vehicle running properly because of the batteries, so we never were
able to run performance tests.
106
2.)
3.)
We cut off the clutch pedal because an EV does not need a clutch.
We use only 2nd and 4th gear to drive with. Up shifts are easy, but
down shifts require a little care.
If we had to do this all over again we would have replaced the 2
chargers with one 144VDC charger and similarly the 2 DC-DC
converters in each charger with a single 144V DC-DC converter.
Tested results: Still TBD
Weight at curb
Weight at GVW
0-60 mph, seconds
Range at constant:
35mph
45 mph
55 mph
65 mph
Range around town driving
(urban schedule based on real world?)
Stored energy
Maximum motor temperatures
107
Chapter 10: Conclusions about Conversions
My purpose is to show you how I would apply my guidelines to building a
safe, reliable, roadworthy EV Conversion. The cost to do it like an OEM
might do it is not significantly higher than what other converters are doing
today. My purpose is to educate people interested in doing conversions on
issues they are probably not aware of. Most “experts” in the EV Conversion
business have been doing EV’s for many years. To do conversions safely
requires more than experience, it takes knowledge and skills that these
experts may not have been exposed to. “OEM automotive engineering” is
not taught in schools or colleges. This knowledge is comes from working in
the OEM’s organization and learning how it is done. None of the experts that
I know actually worked in an OEM’s engineering department designing
vehicles to be ready for production and worked on the OEM’s first production
electric vehicles and conversion vehicles.
EV Conversions can be done in many different ways. And many of these
conversions work just fine within certain limits. Some are not driven in the
rain. Some are not driven very much and some are driven a lot. For many
hobbyists, the joy comes with fiddling with their cars. Some need to be very
careful showing it at displays because there are high voltage safety hazards
that could exposed unknowing people to shocks, if all the precautions of
shutting things down were not completely done. These people feel really
good about what they have accomplished and I respect that.
What I want to do is to see EV Conversions start to appeal to the
mainstream drivers, not just the EV enthusiast. I want to build and help
other build “dumb-it-down” EV Conversions that anybody could use and
operate safely. I don’t want to see cars that could electrocute someone if
somebody forgot to do something to shut everything down. I have an EV
and I drive it all the time. I stop and often get out to answer questions and
forget to turn off the ignition because at rest an EV that is ON sounds no
different than an EV that is OFF. If somebody or child climbs in, they can’t
start it without being in the seat if you use a weight switch in the seat (a
good idea). They can push the accelerator and nothing happens. This is
error proofing which is critical in building safe and highly reliable EV’s or
Conversions.
In conclusion the Cav EV is an example of using my guidelines and providing
the understanding why the things I do are better than some other choices
out there and also providing the knowledge of the consequences of not
following the guidelines.
108
We in the World of EV’s do not want people getting hurt in their vehicles nor
do we want to hurt others who are riding with us. It is not about doing it
perfect, it is only about doing it the best we can with the knowledge we
have.
My hope is to get feedback from all who read this so we can continue to
make the book better. I hope to share it with Electric Automobile
Association to create a set of standards for converters. With a set of
standards, we can move the EV conversion business forward with safety in
mind.
109
Chapter 11: Bibliography
(Update- these worked in 2008 and may not in 2015!)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
http://en.wikipedia.org/wiki/Main_Page I have used Wikipedia
many times in many different places and highly
recommend it as a good source of general knowledge.
http://www.go-ev.com This is the homepage for NetGain
Technologies and was used to provide the Warp 9 motor
curves.
http://www.eastpennbatteries.com/assets/base/0909.pdf Deka
Dominator Gel Cell Battery from EastPenn Manufacturing
Co. Inc. or http://www.dekabattery.com Same general
site as above.
http://www.cafeelectric.com Home of the Zilla controller and
direct access to Otmar Ebenhoech the owner and
operator of the company. There is a great interview
3/26/2008 of Otmar on www.EVWorld.com but you need
to be a subscriber is listen, which is something you ought
to do anyway.
http://www.evparts.com Source of some of my pictures, my
parts and where you can buy lots of parts and kits for
EV’s (let the buyer be ware.)
http://www.evsource.com Another source for high performance
and voltage EV parts for the conversion market. I used
some of their pictures.
http://www.metricmind.com Source for high end AC drive
systems and other assorted parts. Source for my
vacuum pump
http://www.electroauto.com Home to ElectroAutomotive, my
source for the adaptor plate. They sell many parts to
build real world EV conversions.
http://www.ebay.com Where much (if not almost everything)
can be found in your search of the Galaxy to save money,
have fun and build your EV conversion.
http://www.waytekwire.com A great source for many of your
electrical parts needs. They have just about everything to
help put your EV together, wire, cables, terminals, boots,
tools, etc.
http://www.mouser.com Home to Mouser Electronics and their
975,000 different parts.
http://www.mkbattery.com/techref_faq.php Home to MK Power
and their solar power business and the link to a good
110
13.
14.
15.
16.
technical reference to answer questions about the
difference between Gels and AGM’s.
http://www.radsok.com/new/radsok.asp?BU=2 Radsok new
homepage part of Amphenol Industrial Products,
recommend you contact their offices in Fraser, MI.
http://avt.inel.gov/pdf/fsev/eva/99evatechspec.pdf This is the
EVAmerica Technical Specifications document which I
believe is the best document out there to do acceptable
EV conversions for commercial sale. This is a good
starting point and I have used a lot of this in my
guidelines.
http://avt.inel.gov This is the home for Idaho National Labs and
their Advanced Vehicle Testing activity. Lots of good
information. You can read test reports on certain
commercial conversions done over the last 10 years to
help you set your objectives more realistically. You can
compare what OEM’s and converters have done.
http://www.xantrex.com/web/id/10/type.asp Xantrex Link-10
battery monitor gage and their other products including
User’s Manuals which have lots of good information about
batteries.
111
Chapter 12: Appendices
Appendix A - Bill of Materials
UPC
Area
0 VEHICLE
1 BODY
1A HVAC
1A
1A
Part Name
Complete ICE Vehicle
Cavalier take out engine
PTC @144 VDC
heater on-off switch - with
light and on a timer??
high voltage relay for heater
1
Potential Supplier
Qty
for
Veh
EVParts
1
Weight, kg
EstE
WtW
Part Description, material,
process, alternatives
1997 Cavalier
108-156 VDC 1500W PTC
need one 12V switch to high
voltage relay.
EVSource
10A at 150VDC
deck lid, carbon fiber
available but $550 to save 10 lbs
2 Frame
modified for Cobalt EPS
Do difficult, would not
recommend
Frame, Subtotal=
3 Frt Susp
new higher load sprinjgs?
Body Subtotal=
3
2
Not Reqd - close to original
GVW
2
Not Reqd - close to original
GVW
Wheel bearings oK
Front Suspesnion, Subtotal=
4 Rear Susp
new higher load sprinjgs?
Rear suspension and transaxle Subtotal=
5 Brake
a
apply
Vacuum Pump for power
brakes, 12V system
Metric Mind Engg
Portland, OR
503-680-0026
1
1.3
70/6E MES vacuum pump; low
noise with pressure sensor; 12V
5
frt
drag free? Rotors & pads
ok??
clean up and make sure they
don't drag and do work easily
5
rear
drag free? Drums and linings
ok??
clean up and make sure they
don't drag and do work easily
Brake System, Subtotal=
6 Prop sys
6
Accel Pedal (electronic
throttle)
9" NetGain WarP 9
6
Speed sensor (Zolox)
6
motor mount, RHS
6
Flywheel, mods
CafeElectric
1
0.3
Hall sensor pedal - Zilla
EcoVElectric
1
70.9
off-the-shelf run at 144 VDC; at
89 VDC get 28 hp 1 hr rating;
HP goes up with voltage
EV Source
1
Zilla recommended
fabricate to use existing motor
mount
local guy
lighten,thin and balance
Motor, Subtotal=
7 Trans
std M/T with existing clutch
7
Adaptor plate for motor to
transmission
7
use standard drive axles
ElectroAuto
1
change if looks worn; looks good
1
make high quality one - sent
tracing of gear case
1
OK CVJ's and boots?; look good
Trans Sutotal=
9 Strg System
9
EPS power steering
eBay
Cobalt system - Ebay rack
column
eBay
Cobalt ebay
112
9
Intermediate shaft
eBay
Cobalt ebay
9
new wheel, since Cav does
not fit
eBay
buy off eBay new wheel and hub
adaptor
Steering System, Subtotal=
10 Tire Whls
10
a
Tires - 4 new Low Rolling
Resistance tires
4
Sealant, run-flat?? NO
SPARE
4
195/65HR15 Bridgestone
Insignia SE200 (Honda Civic
Hybrid uses same size); get OE
tire through dealer (Article No.
072-497)
TracNSeal Need something
because no spare??
10 b
mounting and balance
Tires and Wheels, Subtotal=
11 Frt End Pnls
11
11
11
Hood, outer - Carbon Fiber
eBay
1
Light weight part - assembly is
about 15 lbs lighter but - $500
Hood, inner - Carbon Fiber
Fenders, light weight
eBay
eBay
2
Light weight part
fiber glass or carbon fiber - but
$250 and maybe 5lbs lighter
Battery Management System
0
use DeltaQ control
Front End Panels, Subtotal=
13 Chas Elect
13 Propul
13
Propul
Battery interconnects-battery
to battery
24
machine Radsok pins, watch
surface finish
13
Propul
Battery interconnect cables
with Radsoks
24
13 cables with two Radsok per
cable - Cable 2AWG
13
Propul
Support, battery underbody
rear seat area
1
5 batteries with upper cover
13
Propul
Support, battery underbody
rear trunk area
1
4 batteries in spare tire well w/
cover
13
Propul
1
3 batteries
13
Propul
Support, battery rad
crossmember
Battery retention hrdw
12
fab something up
13A
Propul
DC Drive Zilla Z1K to 300V
with hairball
CafeElectric
1
7.05
With -P option for HEPI
13
Propul
water pump - for Zilla
Maxijet 1200
powerhead Marine Depot
1
0.2
Zilla recommneded pump
13
Propul
water reservior
13
Propul
interior heater exchanger
13
Propul
Charger (on-board type) for
144 VDC system
13
Propul
Charger cord & reel (take with
or leave at home)
13
Propul
Adpator plugs
13
Propul
Contactor-Main off battery
with brkt
EVSource
1
Albright SW-200B w/ S&H
13
Propul
Master disconnect Switch
Go2Marine
1
Blue sea Systems 9003e
13
Propul
Fuse F2 for controller
protection Fast react
Café Electric
2
Ferraz-Swhawmut A30QS 300V - 500A
Part no. A30QS500-4
fabricate to hold submersible
pump
remount under hood
Delta-Q
2
Could use new design with DCDC
Std 72 V in parallel
QuiQ 7212 charger with Deka
algorithm
Lowes/HomeDepot
1
20A 120VAC capable 10-3 x 50'
adaptor to 20A-240 & 30A-240
(dryer plug)
113
13
Propul
Connectors, High voltage
upgrade to water proof
13
Propul
Radsok pins - ideal machine
from copper and flash silver
plate - but plain brass works,
too. Ideal want 30 micro finish
13
Propul
First Alert safety switch
1
salvage yard part
13
Propul
total length 2 AWG, ft,
orange?
40
2 AWG weldiing wire should be
ok for single wire 150A
continuous; only RED available
13
Propul
total length 2 AWG
orange/black stripe
ft?
didn't worry about this
13
Propul
quant 2AWG 5/16 HD ring
terminals?
Waytek
8
have extra just in case
13
Propul
Waytek
12
have extra just in case
13
Propul
quant 2AWG 3/8 HD ring
terminals
Red insulating boots for
batteries coonectors
Waytek
30
Waytek
10
Wronk in Warren
12
13
13
Misc ring terminals
Propul
Battery - DEKA 8G31
Radsok
24
see Radsok for
dimensions on
8mm pins
12 &
12
Ford car/trk
Amphenol Radsok connectors
with barrel crimps for 2 AWG 8mm pin
Deka batteries need 5/16
threads for neg and 3/8 threads
for positive; recommend cutting
off 1/4" of stainless battery bolt
to reduce overall height and use
brass washer at bottom to get
good solid contact with lead
post.
387.3
battery modules 12V 64.5Ah
C/1 10kWh nominally
Electrical, Chassis, Propulsion, Subtotal=
13
LowV
Wiring Harness modifications - 12V
13
IP
Instrument Cluster
13
IP
small LED warning lights on
dash for battery low, Zilla
fault, battery empty
13
IP
tachometer to drive off Zilla
13
IP
E-meter fuel gage
Radioshack
1
what gage, how much to
connect
1
Need tach
6
1
VDO
Xantrex
1
already have
13
Front Turn Signal Lamp, pass
& driver
eBay
2
LED's??
13
Side Lamps
eBay
2
LED's??
13
Rear tail lamps
eBay
2
LED's??
13
Rear third brake lights
eBay
2
LED's??
1
maybe later; improves aero(?)
needs to be tested; adds weight
1
1
Cavalier, used
Cobalt
Electrical, Chassis Low voltage
14 Bumpers, Jack, Tools
14 Bumper
aero facia front (inclds sides
and rear)
Bumpers, Subtotal=
15 Assy, Matl, total Vehicle
15
Factory shop manual
eBay
15
Factory shop manual
Helms
15
Chassis Alignment
1
15
Painting, re-paint white
1
go from black to light color to
reduce heat load in summer
15
Graphics
1
see what it takes to show it off
114
15
labor, hrs direct & indirect
Don't ask but a good estimate is
about 500 hrs
Assembly & Paint, Subtotal=
Total cost is quant x pc
115
467.03
kg
1028.69
lb
Is not complete
Appendix B – Zilla Set-up Configuration
Main Menu
d)
Display Settings
b)
Battery Menu
m)
Motor Menu
o)
Options Menu
p)
Special Menu
Esc)
Cancel
Battery Menu:
Setting
a)
v)
350
124
BA
LBV
Battery Amp Limit
the Low Battey Voltage limit (80%DOD). The controller will automatically reduce current
so as not to run below this
i)
144
LBVI
Low Battery Voltage Indicator(60%DOD) - the battey light on dash will light below this
level
Motor Menu
Setting
a)
350
Amp
is the series or normal Amp limit for one motor
v)
170
Volt
is the series motor Voltage limit out of the controller
i)
0
RA
Reverse motor Amp Limit
r)
0
RV
Reverse motor Voltage limit
c)
0
PA
Parallel motor Amp limit
p)
0
PV
Parallel motor Voltage limit
Speeed Menu
Setting
l)
5500
Norm
is the forward rev limit
r)
0
Rev
is the reverse rev limit
x)
6000
Max
is the speed above which the Hairball will log an error
Valet mode active or not: "State: 1311 Valet" is active
"State: 1311" is NOT active
Options Menu enter letter to change
Setting
a)
On
Motspd1
On if using speed sensor mtr 1
b)
Off
Motspd2
On if using speed sensor mtr 2
c)
d)
Off
OFF
AutoShift
Stall Detect
On enables auto shifting from series to parallel of two motor systems
On enables Stall Detect - lifting throttle resets - at high currents cuts off in
0.5 sec at low (50A) currents <12sec OFF if not reading speed sensor correctly.
e)
Off
Bat lt polarity
change the output polarity of the indicator indicator light
f)
Off
change the output polarity of the indicator indicator light
g)
Off
h)
i)
Off
Off
Ck eng lt pol
FR
Contactors
SP
Contactors
Parallel
Reverse
j)
Off
k)
Off
l)
Off
m)
Off
Drag race
Amps on
Tach
6 cylinder
tach
Plug in
Polarity
Hairball wired for reverse contactors
Hairball wired for series/parallel contactors
forces unit to stay in parallel when "h" is on and vehicle is in reverse; in some cases this
can help traction
makes tach display motor amps multiplied by 10 instead of RPM
changes the tach output from 4 to 6 cylinders when it is On
reverses the polarity of the Plug In Input
116
n)
On
HEPI
activates HEPI input, only used if Hairball is a -P model
o)
p)
Off
On
--Z1K Scaling
not used
sets the amp dispay scaling to fit the Z1K instead of Z2K; turn this off for Z2Ks
Special Menu
W)
Reset
c)
p)
Clear
Error
Q)
Precharge
DAQ <14>
D)
Defaults
resets Hairball, this is for testiing, reloading code, and handy for reading the software
version no.
clears DTC error history
manually turns on the precharger for the controller, this is only for testing
"Q" is data acquisition, this is how various data can be viewed in real time
"D" resets all the values back to factory default values
117