Tesla Motors

by on July 24, 2006

Wired has a story about Tesla Motors, a company that’s been getting a lot of buzz lately, and is likely to get even more press when its cars launch next year. They’re launching an electric sports car. Whereas most electric cars in the past have been “punishment cars” focused on efficiency and cost at the expense of range and performance, Tesla has gone in the opposite direction, targeting wealthy buyers and focusing on building an electric car that can compete with hgih-end sports car. It can apparently do 0-60 MPH in about 4 seconds.

Their plan is to build the sports car first, and then if that’s successful they’ll branch out and make lower-cost, family-oriented vehicles. They seem to believe that Detroit has largely focused on squeezing an electric motor into a gas-powered car, and that you can squeeze considerable efficiency out of an electric car if you design it from the ground up to run off of batteries. Given the incredible improvements in laptop battery life over the last decade, it seems like this might very well be true.

I’m not convinced that they can make the things competitive with traditional gas-powered cars, though. I see three problems, all related to fundamental properties of gasoline as opposed to batteries. First gasoline has phenomenally high energy density. That is, a kilogram of gasoline contains far more energy than an equivalent weight of even the best batteries. As a result, a lot more space in your electric car has to be taken up by batteries than the volume of the gas tank in an ordinary internal combustion engine car. You can see the batteries in their diagram of the Roadster: they run the width of the car and appear to take up as much room as a row of seats.

Secondly, even at today’s prices, gas is cheap compared with the cost of batteries. According to Wired, the Tesla Roadster has 6,831 lithium-ion batteries. I have no idea what the wholesale cost of batteries is, but given that Apple charges me $50 for a replacement for my laptop battery, I can’t imagine the wholesale price is much less than $5/apiece, which would mean the batteries alone for the Roadster cost more than most people’s entire cars. You’ve got to buy a lot of $3/gallon gas to recover the cost of $30k in batteries.

Finally, there’s the important issue of charge time. This isn’t a big deal if you’re using your car for daily driving, but it will absolutely kill the electric car for road trips. My car will go 300 miles on a tank of gas. When I get low, I stop at a gas station and fill up my tank, which takes about 2 minutes, and I’m good for another 300 miles. I don’t know how fast the Tesla Roadster charges, but if it’s like any of the electronic devices I own, it’ll be on the order of hours, not minutes. That will make electric cars all but useless for road trips that exceed the one-charge range of the vehicle.

Still, there may yet be considerable room for improvement, both in vehicle energy efficiency and in battery technology. If they can improve efficiency and/or battery capacity by a factor of 3 or so, then these cars will suddenly be a serious alternative to the internal combustion engine for ordinary drivers. And if there is room for improvement, it seems likely that a company focused entirely on electric vehicles will be far more likely to find it than Detroit companies for whom electric cars are an afterthought.

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