This car project was inspired by the last round of gas price increases. Since hitting an all time low around 1999, gas prices have been rising again. Right now, new oil discoveries are decreasing year to year, while worldwide oil consumption is increasing. Obviously, this is a bad trend.

Back in 1975, fresh out of school, with recent gas shortages and odd/even plate gas rationing on my mind, I decided to build an electric vehicle. I converted a 1967 Corvette to battery power using 18 golf cart batteries and a separately excited DC motor. The car had regenerative braking, which was unusual at the time, but you had to downshift to take full advantage of it. Range with the lead acid batteries was only around 40 miles, but the car would do 60MPH, and weighed 3800 lbs. It was a lot of fun, but not terribly practical with a 40 mile range and a battery life of 2 years.

Today, we have Lithium Ion batteries that easily provide ranges of 80 to 250 miles, depending on the battery size. Their life is projected to be well over 5000 cycles, which means they should last the life of the car. AC Motor drives eliminate the brushes on DC motors and allow higher speeds, lighter weight and higher efficiency. With fuel prices dancing around $4 per gallon, electric vehicles are beginning to make sense. With an electric rate of $0.18/kwh and energy consumption of 280wh/mile, my home-built EV only costs $0.049/mile in electricity cost. At a gas price of $3.70/gallon, a gas powered car getting 32 mpg costs $0.116 per mile in fuel cost. A diesel powered car getting 50mpg with a diesel fuel cost of $4.10 per gallon costs $0.082 per mile in fuel cost.

Of course, what really matters is the total cost of ownership. Right now, electrics will require less maintenance (brakes should last 100K miles or more and they don't require oil changes), but initial purchase price is higher due to the relatively high cost of lithium ion batteries. So in 2011, you have to simply want one. It's tough to justify a $25K+ EV based on saving under $1000 per year in fuel cost. However, in a few years if gas hits $6 per gallon and the cost of electric vehicles gets down to the cost of equivalent gasoline powered cars, electric vehicle sales will take off.

Since the big expense in an electric vehicle is the lithium ion battery, it follows that whatever you can do to reduce the size (capacity) will reduce weight of the vehicle and the cost of the battery. So the goal of this project was to reduce the weight of the vehicle as much as possible. I had a target weight of 1800 lbs originally, but that crept up to 2000 lbs by the end of the project.

In order to meet that sort of a curb weight target, I would need to have a base vehicle weight on the order of 1200 lbs. I looked at all the cars currently in production, and found that NONE of them weigh less than 2700 lbs. Which means that once I stripped out the engine and associated parts, I'd still be over 2000 lbs for the stripped vehicle. I had already done a conversion project years ago, and I did not want to deal with the compromises associated with a conversion.

I had seen an article in Car & Driver about the Locost homebuilt sports car. It uses a steel space frame made of 16 gauge 1" square tubing. Coincidentally, the same technique had been used to make the frame of an EV at Cornell in the mid '70's. So I decided to do a ground-up hybrid vehicle, with a small gas engine-generator combination to enable it to cruise indefinitely on gasoline when necessary. Battery-only range would be around 50 miles using Lithium Ion batteries. After almost a year of planning, in May of 2007 I bought a 1988 Fiero as a donor vehicle. It's been slow going, as I have a full time+ job that occupies most of my time. This build diary shows the step-by-step details. There's a spreadsheet that shows the weight budget, but the car now weighs 2050 lbs, including a "larger than planned" 20kwh lithium ion battery that gives it a range of about 70-90 miles, depending on driving conditions.

The final question becomes, "OK, so what does this prove?". That's a tough question. My personal belief is that there needs to be a significant technology shift in basic vehicle construction technology. Todays stamped steel body construction is cost effective for conventional vehicles, but when you essentially double the cost of the drivetrain (motor/controller/battery), it increases the budget for weight reduction techniques. In other words, the amount of money you can spend to save vehicle weight goes up, and composite construction becomes a viable construction technique. I think production EV's can not simply share a gasoline-powered vehicle platform. They need to be built on a platform designed for them. That platform needs to be extremely light to minimize the size, weight and cost of the drivetrain. The original Honda Insight is a good example. It had an aluminum body, and extremely good aerodynamics.