Tesla: Not for Geeks Alone

The electric Roadster from the start-up Tesla Motors of San Carlos, Calif., got an enormous amount of news media coverage—including the cover of IEEE Spectrum’s April issue—well before it was deemed legal to sell in the United States. But it’s undeniably sexy, making it a good counterargument to the public image of electric cars as the playthings of geeks and ecopurists.

Tesla chose not to concern itself with the economics of mass production. It charges nearly US $100 000 for the Roadster, a two-seater that leaps from a standing start to 100 kilometers per hour in 4 seconds. As of mid-August, the company had sold more than 500.

Tesla has assembled 6831 3.6-volt lithium-ion cells—the finger-size variety used in consumer electronics—into a 450-kilogram battery pack that holds 56 kilowatt-hours. That’s enough, the company says, to cruise some 320 kilometers (200 miles). To keep all those cells pulling together, despite their differences, the car uses complex monitoring and interconnection hardware with liquid cooling, ensuring that a failure in one cell won’t spread to all the others.

Life span is the weak point. But because the Tesla lacks an engine, it isn’t bound by the California emissions regulation requiring that a power train last for 10 years and 150 000 miles (240 000 km). The company expects the battery to lose up to 30 percent of its capacity after five years. If you then want to buy another battery, Tesla says only that its own cost for the battery pack lies “north of $20 000.”

—John Voelcker