2011 Chevrolet Volt Lithium-Ion Battery (© General Motors)Click to enlarge picture

The Chevy Volt's advanced battery pack, which contains 288 cells, is based on lithium, a mineral that some analysts believe will be in short supply.

If you believe the headlines, electric vehicles and plug-in hybrids are about to take over the world. Soon we'll all be silently gliding around in Trader Joe's parking lot, free from foreign oil, climate-change anxiety and all other earthly cares. This year's North American International Auto Show in Detroit drove the point home as Ford, Tesla, Porsche, Mercedes-Benz and others flaunted electric cars of all species. More importantly, the first real EV offerings, the Nissan Leaf and Chevy Volt, recently hit the streets to much fanfare.

Indeed, it seems that electricity is winning the alternative-fuel war, which makes us both excited and a bit concerned. Carrying all those electrons around requires big, high-voltage batteries. And many questions are yet to be answered about these oversized copper tops — some good, some not so good.

Here, we examine five of the most troubling concerns about EV batteries.

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1. Will This Thing Die on Me?
People don't like being guinea pigs, and many would-be EV owners are wondering if the large, pricey batteries that power electric cars are going to last. The bottom line: Nobody knows yet. Makers of plug-in hybrids and EVs tell us their batteries will last "the life of the car," but that is vague. Both the Nissan Leaf and Chevy Volt carry an 8-year, 100,000-mile warranty on their battery packs, which is encouraging. Also, the track record for conventional hybrid batteries has been strong, with Toyota Prius batteries easily living beyond 200,000 miles.

But the lithium-ion batteries used in plug-ins like the Volt and pure EVs like the Leaf are different from Prius batteries. They are composed of different chemistries and are much larger. They also endure greater punishment during daily use. A Prius battery delivers power in short bursts as it helps the gasoline engine along, and is then recharged as the car brakes. EVs and plug-in hybrids, on the other hand, deplete their batteries nearly all the way — a process called "deep discharge" — which is significantly more taxing on the cells and can diminish their life span.

However, your primary concern with these batteries should not be their outright death, but rather a gradual drift into senescence. Lithium-ion batteries lose storage capacity over time; how long does your 5-year-old laptop battery hold a charge? This means your EV's range will decrease as it ages — and the more aggressively you drive, the faster that happens. Nissan and GM both acknowledge that their high-voltage batteries will hold less and less electricity over the years, and that their battery warranties cover only what they deem abnormal decreases in range. This means that if you buy a Leaf, which has a 100-mile range, and your commute is 50 miles each way, you might have to move in a year.

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2. Will There Be Enough Lithium to Support EVs?
News headlines like "Will Afghanistan become the 'Saudi Arabia of lithium'?" have appeared in the press a lot recently. As the name suggests, lithium-ion batteries, of the sort favored for electric cars and plug-in hybrids, are based on lithium, a mineral mined from the earth or extracted from brine. The world's current supply of lithium comes from very few countries. A third of the current supply comes from Chile, but Bolivia and Afghanistan also have massive deposits. If Americans start driving electric cars in earnest, the question naturally arises: Will we be at the mercy of the world's producers? It's a question that sounds eerily familiar, right?

At least for the foreseeable future, it seems we're in good shape. A recent research paper from the Argonne National Laboratory in Argonne, Ill., concludes, "It appears that even an aggressive program of vehicles with electric drive can be supported for decades with known supplies." Analysts also argue that as the demand for lithium ratchets up, new deposits will be unearthed. Greg Cesiel, engineering group manager for the Chevy Volt, says General Motors isn't worried: "There's a lot of lithium out there. We don't anticipate any shortages."

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