Introduction: Converting an Old 84 VW Rabbit GTI into an Electric Car By James Keele May 26, 2012 Over a time period of about four years, I actually converted two gas powered cars to electrical powered cars (ev s). Ev is short for electrical vehicle. They are a 84 VW Rabbit GTI and a 94 VW Golf. I started out with the Rabbit and the story I am telling below is about the Rabbit conversion. Both cars now have almost identical electrical parts and run fairly well. Being a retired electrical engineer I decided at the onset that I would select the motor and batteries to use. Also, I would design the electronics which mainly include the motor controller, the overall motor loop circuit, and the battery pack charger. A smaller design was the tachometer sensor. All these jobs together were bigger than I anticipated, but they were successfully performed over this long time period. I even wrote a computer program to calculate the performance of the Rabbit ev. As a result of all this effort I now have what I consider a fairly well balanced electric car design that is practical and affordable. It is practical only for commuting in a small town and not for big town freeways although it capability on a freeway has not been thoroughly tested. Electric cars have been around for a long time. In fact some of the first cars ever made in the early 1900 s were electric. In the 70 s and 80 s people were converting gas cars to all electric. As a result companies sprung up that supplies parts and kits for conversion of cars to electric. In the late 90 s even GM manufactured EV1 and rented the car to people in California. Later they came along and crushed them. Foreign manufactures and ordinary people got in the act of making and converting cars. My basic idea was to use some of the latest electronic advances in semiconductors to design the most simple and inexpensive electric car possible. Also, being trained in analog techniques as well as digital techniques and computer science, I could focus an array of talents on a project unimpeded by corporate dictatorship, time limits, and marketing demands. Story of the rabbit conversion: Back in the winter of '07, I decided to convert a car to an electric vehicle (EV). I had seen the movie "What Killed the Electric Car" and I had a friend who also wanted to convert a car to electric. We wanted to see the limitations of an allelectric car. All this motivated me to get started. I had a '83 Ford Ranger pickup that I might have used, but decided that would be too heavy. Not knowing anything about converting a car to electric I started out. I searched the internet about EV's. Eventually I decided on an '84 VW Rabbit GTI for the conversion which I found on
the internet. It was in a small town in Iowa just north of Cedar Rapids. I purchased it for $1400 over the internet from a used car dealer. To get the car I rode the train from Lamy to Fort Madison, Iowa. While on the train I met a woman who was getting off there and traveling north. She rented a car and gave me a ride to the small town. I gave her $60 for the ride. On arriving I paid the dealer $1400 in cash. I got in the car and started driving it home to Santa Fe. I made it alright without major incident. It took me two days. It was the cold of winter. I have a Mexican mechanic friend who agreed to take out the motor, the gas tank, the transmission, and the clutch for the motor. I had the car towed over to my house after he did that. The brakes were shot and I had to replace brake cylinders, the brake lines and the master cylinder. The hand brake cable was broken; I had that fixed along with replacing a strut in the front right wheel. My friend was being sensible about his conversion. He conferred with the companies who sell conversion kits and followed their advice. Me, I blundered in from scratch. I purchased a small 6" diameter motor from a used motor dealer on the internet and had it shipped to me. I designed a direct mechanical interface between the motor and the left front CV axel. I had a machine shop construct the interface. Also, I purchased a used electronic magnetic imaging driver over the internet which I would convert to a motor controller. I was going to do the electronic design all the way. After a modest review of batteries I purchased 14 12v AGM batteries from a local car parts dealer. I would use these for my electric power. Then I designed a battery charger that would charge up 13 12v batteries connected in series all at one time. By the middle of '08 I had all this installed and gave the EV a try out. I was able to go down the street (a small slope down), but going up the street proved more difficult. I gave the motor all the juice I could and the motor burned out. I needed more motor power and I decided I needed the transmission also. I went back to the Mexican mechanic and retrieved the transmission and the flywheel-clutch. My next try was installing three 8 hp dc motors connected in series with their mechanical output hooked together by a strong chain to the transmission. This turned out to be a mechanical nightmare, but it worked. I was able to drive up and down the street with the motors and the transmission, using the original clutch and flywheel. I saw how a large single motor worked well in EV's from riding in EV's converted by two friends. I decided to purchase a large 9" dia. Advanced DC motor, a new one I found on the internet with reduced price. I got Electro Automotive to construct a mechanical adapter from the motor to the clutchflywheel-transmission. That needed to be done with great precision and they did it. I installed the motor in the Rabbit. By this time the AGM batteries had played out. I discovered that the charger I had designed had a voltmeter that was not properly calibrated. It was about 5% off, reading high, so I was not charging my AGM batteries sufficiently. Fixed that, and purchased a new set of batteries: Some 12 12v Marine RV deep-cycle batteries from Sears. They were rated at about 115 ah. I installed them and ran the car awhile. Performance was considerably improved. I was able to keep up with the other traffic in town. However, my range still was not
what was calculated. So, I up the PWM frequency on the controller. That fixed that problem. Now my performance and range is about what is calculated. It had taken me about 2 years work to get that far. Along the way I designed formal printed circuit boards for the controller and the charger. Those were updated from time to time as the designs were improved. Its more like a normal gas car now, except for all the luxury features like power steering, power brakes, power windows, heater, and air conditioner. Also, I designed and installed a tachometer sensor circuit which works fairly well with my old tachometer meter on the dash. I found the tachometer very useful in driving the ev. I let the rabbit ev sit on my driveway for a year or so while I converted the vw golf car. The golf has a better body and mechanical wheels, brakes and transmission. I took the lead acid batteries out of the rabbit ev and installed them in the golf. Lead acid batteries, I discovered, are a real problem for ev s. First, they are heavy (about 750 lbs for 12 of them). Second, they tend to sulfate real easy and lose their power. Third, they are real messy to work with. Their acid caused some holes to appear in my pants. So I decided to go with Lithium batteries. They hold more charge for their size than lead acid batteries. Also, they hold their voltage until almost totally discharged. I ordered them from a ev parts place who got them from China. They are not available over here from US manufactures. These batteries performed so well in the golf ev, that I decided to get a set of lithium batteries for the rabbit ev. The only place where I now use a lead acid battery is for normal 12vdc usage in the car: like wipers, turn-signals, radio, lights, brake lights, etc. Currently I charge the 12vdc lead acid battery separately from the lithium battery pack. On the golf, the 12vdc battery is supplemented with a dc-to-dc converter powered by the lithium battery pack. I had taken the back seat out of the rabbit ev and there installed the battery pack. The first battery pack consisted of 10 12v lead acid batteries in a metal frame. Two lead acid batteries were installed under the hood where the radiator was. All together the combined weight of the batteries was about 750 lbs. The rear end of the rabbit sunk with all this weight. When the lithium batteries came, I installed all 39 of the cells where the back seat was. Their total weight is 320 lbs, quite a reduction of weight. The rear end of the rabbit now looks more normal. Recently, I took the rabbit out for a range and speed test on the frontage road by the old horse race track. The top speed I observed, the pedal not all the way to the floor, was about 65 mph. The range turned out to be about 46 miles with the lithium batteries discharged to 97% of their capacity. You don t want to discharge the batteries that low on a regular basis, so I specify the range to be 38 miles at 80% discharge. The curb weight, the weight of the vehicle without anybody in it, was measured at a gravel company to be 2100 lbs. This is a good weight for an electric vehicle.
I am planning on installing a 124v to 12v dc-to-dc converter to supplement the 12vdc accessory battery. This is so I can drive the vehicle at night with the lights on so I don t have to worry about the 12v battery being discharged. This dc-to-dc converter essentially replaces the old car alternator that keeps the 12v battery charged. Below and some pictures of the converted rabbit. Figure 1: View under the hood showing the controller, motor, transmission, pulse width modulator, and accessory 12v battery.
Figure 2: View with the hatch raised showing the lithium battery pack. Figure 3: View showing the dash instrumentation, control panel, and gauges that came with the rabbit gti.
Figure 4: Overall side view of the rabbit ev. Figure 5: Front view of the rabbit ev.
Figure 6: Picture of the 144v battery charger.