Don’t Overcharge Your Electric Car!

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As 2010: The Year of the Electric Car dawns on consumers across the land, an obvious question is emerging. If EVs (and plug-in hybrids) use the same flavor of lithium-ion batteries as laptops and other consumer electronics, will leaving them plugged in too long kill the battery over time?

The answer, according to Venkat Srinivasan, an advanced battery researcher at the Lawrence Berkeley National Lab, is YES! His overall explanation is fairly technical, but the upshot is clear: If you leave your EV plugged in too long, it will fry the battery.

The answer is smart charging—charging that knows when the battery is full enough (and that could mean only an 80 percent charge) to interrupt the process. This will be an essential EV technology, as many early EV and plug-in hybrid owners will be juicing their rides off their home supply. This could take six-to-eight hours, which as Srinivasan points out, would means that you’d have to remember to unplug your car in the middle of the night, if it, the battery, or the charger isn’t smart enough to do it itself.

My take is that home smart charging will be vitally important to the successful adoption of extended-range hybrids, such as the forthcoming Chevy Volt. Because these cars will have a range-extender option in the form of a small gas engine, they’re more likely to be charged in a leisurely fashion at home. Full-on EVs, like the Nissan Leaf, will appeal more to fast-charging enthusiasts who may install higher voltage charging at home or seek it out at other locations.