The first thing that will determine the performance of
your EV car conversion is the battery pack. For example,
let's say you have designed a battery pack that has
twelve 12V Trojan T-1275, 150 AH Batteries in series.
This would give you 12V x 150 Amp Hr = 21,600W or
21.6 kWh of energy. This is 3.6 kWh more than the i Miev, and 2.4 kWh less than the Nissan Leaf. Look
at the weight next. The batteries are 82 lbs each for a
total of 984 lbs or 447 kg. This means that your donor
car should be in the neighborhood of about 2,000
pounds max if you want good performance and range.
Note that these are only guidelines; you will need to
look around at some batteries, storage capacities,
the space you have to place the batteries and then
do the math. For example, Trojan batteries are rated
at a 20 hour rate. An EV uses the power much
more quickly.
The next step is to select a donor car. You want a car that you
like first of all. The car should be light enough for efficiency, and
have enough room for the batteries you choose. Measure the empty
spaces you plan to use to store the batteries. This will determine
height/width of the batteries. Check to see if there are ready made
motor adaptors for your EV car conversion donor car.
You may have to deal with electronics with newer cars. We did not
have to worry about that having a 1980s vintage rig. In any case, try
to estimate the room you will have.
Once you have your donor, find a place you can work in for an extended
time. We spent a year off and on. You will need the basic tools, plus
a few electronics tools: voltmeters, soldering gear, stripping and crimping
tools, and insulated wire cutters for example.
This brings up the issue of safety during your EV car conversion:
SAFETY FIRST! Remember that you will be working with high voltages and amperages. The combination can zap tools right out of your hands, speaking from experience. So, watch it!
When you're ready, get started on your EV car conversion by removing donor car parts. Remember to label just about any wire left hanging! It will pay off if you take time to do this. You might want to take pictures as well.
Install the motor. For the example, we selected a 9 inch Series wound DC motor. You want something that will handle 144 volts nominal and 158 volts or so with a fully charged 12 volt array. If your donor car is really light, you can get by with 120V. AC motors are now coming into use, but we will restrict the discussion to DC for simplicity on this EV car conversion.
These are readily on the market and are configured for EV use. This motor can use the 144V from the battery pack and will give a 3,000 lb /1364 kg car good acceleration. You will need an adaptor. There are kits readily available for many
cars. If you choose a car with no kit already made, you will need to do some
machining before moving on to installing components, the next step.
Regarding transmission and brakes: Your EV car conversion will not have engine vacuum to hold it in place parked on an incline. You will need a good hand brake or whatever you want to call it. Make sure this is working. Ours was so tight once that a guy towing the car forgot to release the brake and the tires started smoking!
If you are using manual gears, reverse gear will be built into the transmission.
Alternately, you will need to wire the motor controller to run the motor in reverse.
So, you may have to install a reverse switch and wire it to the controller.
