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interview > eberhard > clip: eberhard 12

Eberhard 12 (1:37)
Topic(s): Auto Industry / Electric & Hybrid
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Well, there are some car companies around the world that have proposed making plug-in hybrid vehicles and the like with a fairly short electric range, maybe a 40 mile electric range, and they see this as a stepping stone toward eventually building an electric car with a long driving range. It's a baby step; we can first build a car with 40 miles and someday we can think of a car with maybe 250 miles. And that allows them to kind of experiment and step their way into batteries.

That sounds logical on the face of it but if you think about it in detail, it's actually the opposite. The demands on the batteries of a car with a short driving range are much, much higher than they are for a car with a high driving range. And the only way to understand that is to think about if you look inside the battery pack and pick out one battery of any size, whatever the cell might be (here's my cell), if I say ok, that cell is designed to work for—lets just make up some numbers—this is designed to last for 500 full charged discharged cycles, which would be the same as 1000 half cycles or 2000 quarter cycles, but lets just call it 500 full charged cycles, ok? And you put enough of those into a battery pack that you have a 250-mile driving range. Well if you take 500 times 250 that means that that battery pack is good for 125,000 miles, simple math, right? If I take that same exact technology cell, 500 cycles, and I build a smaller battery pack, one that is made for a 40-mile range, then I've got 500 cycles times 40 miles. That battery pack is worn out in 20,000 miles. So making a car with a short driving range is not a baby step to making a car with a long driving range, it is the opposite; it's a harder problem to solve. And in fact if I had the room in the car, I would make a 500-mile range; the battery pack would last twice as long



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