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A False Scare for Tesla

A blog posting recently made the rounds regarding a fatal design flaw in the Tesla Roadster. The blogger claims that some Roadsters have become "bricks", with non-functioning batteries requiring a $40,000 fix. The blog is dead wrong about most of the technical facts it claims to be reporting. Don't blame the blogger, however: he's only participating in a trend of misinformation about electric vehicles that is starting to impact the reputation of the fledgling industry.

Here's the primary fact that the blogger in question doesn't understand: the Tesla battery pack is not a battery. It's a collection of more than 8,000 individual batteries. Each of those cells is independently managed. So there's only two ways for the entire battery pack to fail. The first is if all 8,000 cells individually fail (highly unlikely except in the case of something catastrophic like a fire). The second failure mechanism is if the battery management system tells the pack to shut down because it has detected a dangerous situation, such as an extremely low depth of discharge. If that's the case, all that needs to be done is to tow the vehicle to a charger, recharge the batteries and then reboot the battery management system. This is the most likely explanation for the five "bricks" that the blogger claims to have heard about. They probably aren't actually bricks, but cars in need of servicing.

Another error on the part of the blogger is the claim that if the cars discharge fully, the battery packs will be damaged. This is blatantly false. The battery management system of the Tesla Roadster keeps the battery from being discharged to a damagingly low state of charge under normal driving conditions. It's true that a full discharge to zero percent state of charge can potentially be damaging to a battery. However the battery management system of the Roadster won't allow the car to reach that low level of charge.

There is a fundamental problem when any rechargeable battery is discharged and then left to sit for months. Any boat owner understands that that's why you plug in a trickle charger when the craft is put into storage. The same should be done for any electric vehicle. However, to imply that the Tesla Roadster has a fundamental design flaw because of the nature of electrochemistry is like saying that Chrysler has a fundamental design flaw because its engines will be damaged if you drain all the oil out and then drive cross-country.

The blogger in question is, unfortunately, not a single voice in the wilderness. He's part of a widespread trend throughout some parts of the blogosphere and some parts of traditional media to politicize and demonize the electric vehicle. This trend has in turn damaged the general reputation of the automakers taking risks in building and selling these vehicles. This isn't the only problem that electric vehicles have today (overpricing and bad choreography have done their damage too). But there's an antidote for this type of misinformation: confronting it with facts.

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