It’s about time that I put all of the information I have learned on how to build an electric car together in one place. As you know, my project was a success and I’ve been driving my car for a few weeks now. I want you to build one for yourself too. It’s a challenging project but it’s also extremely rewarding to be able to drive where I need to go without ever buying gasoline. The car is simple and I haven’t had any EV related issues as of yet. I plug it in at the end of the day and it’s ready to go again the next morning.
So how did it all come together?
Well, it’s best to start at the beginning, I had to choose a car. Most of you don’t know that the Sprint wasn’t my first choice for my EV project. I originally bought a 1990 Nissan Sentra hatchback to convert to electric. It was only after doing a mountain of reading on how to build an electric car that I realized this wasn’t a good choice. Simplicity is key, and that car wasn’t simple. It had power steering which would either need to be run by an independent electric motor or eliminated altogether.
That’s when my buddy (shout out to Dave from Innovate Imageworks) donated a 1991 Chevrolet Sprint (Geo Metro) to the project and I was off to the races. That car is one of the most popular vehicles for electric conversion so I knew that I would have support the whole way through.
I will break the process down into some simple steps for you.
If it’s your first conversion, just make it easy on yourself and pick something off this list. All of these cars have been converted a hundred times and there’s tons of support available online. If you don’t want to build one of those cars, go to a parts supplier like Canadian Electric Vehicles and choose something that they sell an adapter plate for. This is the one part of the conversion that is vehicle-specific and I didn’t want to try and build myself. The adapter plates retail at around $800 bucks but I figured with my limited experience, I could easily spent weeks trying to build a crummy one myself.
This is something I would do differently next time. I cobbled together my parts as I went along and although it worked out and I got some great deals, I will source my parts before I begin next time. The project took long breaks while I was scraping money together and waiting for the right deal on parts. It was a bit discouraging and ended up taking me a year and a half to finish the car. Hunt for your parts ahead of time so you can dive into the project head first.
Here’s a basic list of what you will need:
- Motor, controller and pot box (throttle control) – these can often be bought together as a kit to save some cash.
- Adapter plate – unless you’re a fabricator, don’t cheap out here. Buy a factory made plate-you’ll be glad you did.
- Batteries – I used 8-12V deep cycle batteries in my car. I will add more when I get around to upgrading the springs.
- Charger – there are lots of options here.
- Contactor – for connecting and disconnecting the high-voltage power.
- Vacuum brake booster – I haven’t installed one yet, the Sprint seems to stop fine without it.
- Instrumentation – a $10 multimeter works fine, if you want to be fancy you can spend $300 or more.
- Cable – for connecting batteries and components.
- Battery racks/box – I recommend building these on your own, it’s not that hard.
Once you have your parts, you’re ready to go. Here’s how to build an electric car:
3. Remove the motor, exhaust, fuel tank and cooling system
This is fun so don’t let it intimidate you. Depending on the size of your donor car you may need a friend of engine hoist to pull the motor out. I just did it with a buddy. Drain all of the fluids and dispose of them properly. Remove and drain the transmission.
4. Attach the electric motor and hub to transmission
This is plug and play if you buy an adapter plate kit. My coupler mated the electric motor output shaft to the flywheel easily and the adapter plate bolts right on to the face of the transmission. Lifting the thing is far more difficult than figuring out where the bolts go.
5. Install the transmission/motor in car
This requires a mount to support the motor. You can buy these for most common cars for conversion or you can build one yourself. I chose to build this but if I had it to do over again I would just spent the hundred bucks and buy the mounting collar. It took way too much time.
4. Build battery racks and install batteries in car
This will be a very different project if you use an S10 rather than a Geo Metro. If you’re converting a truck, personally, I would just build a rack in the front of the bed out of angle iron and box the batteries in…actually, you could even put them in a tool box. Lots of guys converting pickups put the batteries between the frame rails and design a system to lift the box to access them. I get tired just thinking about all that work.
If you’re building a small car like me, weight is more of an issue. Test with batteries front and rear to get your weight right. Check by looking at the gap between the top of the tire and the fender to give yourself an idea about weight distribution. I found that mine is just about right with 4 batteries in the rear and 4 in the front (at the moment, I’m running 4 rear, and 3 front while I figure out where to put the 4th.
Rear racks are simple, you can use angle iron or an old bed frame to save money. Just lay 2 pieces across the truck and space them properly for your batteries. Drill through the iron and the truck and securely bolt the racks in place from under the car. Here’s where it gets simple. I got carried away thinking about complicated tie down systems at first, but then in the end I just bought some ratchet straps and secured the batteries to the racks that way, it works swimmingly. I needed to use a little more ingenuity for the front racks. Ok, no I didn’t, I just stole this guy’s idea and bolted them to some existing holes in the chassis.
5. Install controller, contactor, pot box and charger
I just mounted the controller and contactor on a 1/8″ plate of aluminum. Find a place under the hood where you can mount this stuff. The pot box will be limited by where your throttle cable can reach. My chargers are still floating around unmounted in the trunk :).
6. Wire batteries to controller and motor
Using a heavy gauge cable (I chose 1/0 based on advice from guys on diyelectriccar.com) and lugs, wire up the high voltage system. I won’t go into this but there are wiring diagrams available for free online. If you buy your controller from a supplier they can provide you with one as well. I would get some advice from the diy electric car forum if you need it, I sure did.
7. Wire up contactor, instrumentation and charger(s)
Again, this will depend on your specific parts and application so seek out some advice from the suppliers of your parts or forums. It’s not a lot of work. I have one wire that interfaces with the existing electrical system on my car….one wire, it’s to connect the high voltage power when I turn the key.
This is an over-simplified explanation of how to build an electric car. I used a conversion guide when I converted my Sprint. It’s worth considering. It was great to have all the info in one place.