Why Tesla Rules: Huge Battery With Small Cells

By · November 06, 2013

Tesla Model S at the Frankfurt motor show

Tesla Model S at the Frankfurt motor show.

People sometimes ask ask me, “What's the best car in the world?” Some will say the best is Ferrari. Others say it's a Porsche or the Mercedes S-Class—while others favor something more mundane, like a Volkswagen Golf, because it's very dependable affordable transportation. If you're talking specifically electric cars, the answer is obvious: the Tesla Model S. Nothing else comes close.

Unlike gas cars, there is a huge gap between the ruling Tesla and the second best EV. Does Tesla know something the other companies don't?

Size Matters

The Tesla Model S, the BMW i3, the Nissan LEAF and the Renault Zoé are all clean sheet designs. They're all two-wheel drive with a battery below the floor. But the chief difference that explains why the Tesla is miles away from the competition is: battery size.

About eight or nine years ago—I can't remember the exact time—a BMW spokesperson told me that it was impossible to build an electric car with a decent range because that would require a battery weighing more than 500 kg (1,102 pounds). But that's exactly what Tesla Motors did.

The battery of Model S Performance weighs 1,323 poiunds. It's so heavy, so big and so expensive that it gets every other car manufacturer scared. But it's absolutely the defining factor behind the Model S's exceptional performance. If the car had less battery, it wouldn't be so powerful, and it couldn't charge as fast. A bigger battery means that more electrical current can be pumped in or out.

Tesla Model S at the Frankfurt motor show

Motor of the Tesla Model S at the Frankfurt motor show

Of course, there's a technical challenge. Even in a big gas car, a V8 engine weighs less than 500 pounds. Chassis engineers are not used to coping with a single element this heavy, but Tesla proves it can be done.

But there's somebody even more frightened by a big battery EV than the engineer? Accountants! (And the car companies that act like accountants.) Big battery equals big money, but Tesla has an ace in the hole: its choice of cheaper very small cells, sometimes called consumer cells. Unlike the choice of a large battery, the choice of very small cells seems really odd. It's like building a house with matchsticks.

This choice was pioneered by AC Propulsion more than 10 years ago, and it seems strange that there are about 7,000 little cells aboard a Model S. But it works, so nobody should look any further for a robust solution to EV range and power.

With only a few thousands cars on the road, we still don't have enough data to say if those little cells are more or less robust than the bigger ones that other car manufacturers prefer.

So that's the big non-secret: a big battery made out of very small cells. No other difference between the Tesla Model S and the other EVs is nearly as significant.

If a car maker needs a cookbook to compete with Tesla, it doesn't need to look any further. The mystery is that nobody is copying Tesla. There's no word of another car manufacturer working on an EV with a large battery pack from little cells. (When Martin Eberhard, Tesla's founder, briefly worked for Volkswagen three years ago, it was rumored that VW was considering the small cell approach. But Eberhard left, and that was that.)

Isn't it revealing enough that Tesla dropped its base model with the small 40-kWh battery? Like in the fast food where most customers want the Supersize menu, EV customers want large batteries. And they appear ready to pay for it. So Tesla will get all those customers, with no competition.

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