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