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Is GM Volt's Battery Cooling Approach Better Than Nissan Leaf's? Here's How They Both Work

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Nissan Leaf's battery, as exhibited at this year's Paris Motor Show (c) The Green Optimistic

Nissan and GM both have big plans for the highly-expected pure electric and plug-in hybrid waiting to be released this month in the United States. Battery capacity is one of the fears the users of such cars have, and the fact that the manufacturers will use lithium ion batteries can be an issue.

Although present in the market for 20 years, lithium ion batteries haven’t been tested intensively on vehicles, but rather on laptops and other small gadgets, where they had some fire-catching issues in some rare cases.

Lithium ion batteries, unlike their nickel-metal siblings, have better energy densities and weigh less. In an electric car, they will have to withstand extreme heat and cold temperatures and extreme vibrations for at least ten years, the expected lifetime of an automobile (remember those days when they were guaranteed for life?).

Two different approaches make the difference between GM’s Volt and Nissan’s Leaf: the way they cool the batteries.

Nissan’s approach consists of a simple fan that blows air on the batteries. The company says this is enough to keep the entire thing working properly… but for how many years? It’s already common knowledge that if you heat batteries too much too many times, they’ll eventually lose their capacity of holding the charge, and this will surely call on some drivers’ budgets. The real life fact is that Nissan is probably only appealing to those who can afford a Leaf for $25,280, and those who do and actually buy it don’t think about keeping it for that long.

Yes, that’s an option, but what about the green part of the battery, where after living a warm or even hot life, the thing is supposed to get changed, and the more often that happens, the more carbon dioxide will get emitted into the atmosphere due to its processing. And let’s not talk about it catching fire or something, because you’ll have cold shivers for the rest of your green Leaf driving time.

GM’s approach is a little more cautious, and resembles Tesla’s. They use liquid cooling on each battery element, which ensures that any two (flat) elements in the battery won’t have more than a couple degrees Celsius between them. This should increase the lifetime and at the same time the safety of the battery, as the company mentions that if one element catches fire, this won’t affect the others. And it’s more compact, too.

Another difference between the two is that the GM battery can heat itself up from a 1800W heater, while Nissan’s is not even an option at the time I am writing this article or when it will be launched. Only the models appearing sometime in 2011 will feature heating as an option, and for those that don’t have it installed, it’s not possible to add it later.

Now, what is the best? Time will decide. I guess Nissan did that fan job with cost reductions in mind, and for the sake of launching an electric car fast and as cheap as possible. GM, on the other hand, thought more intensely about the Volt project, and designed it more thoroughly. If it proves better than Nissan’s (and my guess is it surely will), GM’s battery model will probably be followed in the Leaf or any other model they will launch in the future.

[via technologyreview]

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1 COMMENT

  1. A battery heater in an electric car is stupid.
    It self heats during charging and discharging.
    I am skeptical without tests showing input power of the heater is recovered by more efficient battery use once warmed up.

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