Electric cars can't stand the heat – or cold

Extreme temperatures are the enemy of battery range and when the battery is also the fuel tank, a hot or cold day can stop electric vehicles in their tracks.

For best operating results and also longevity, EV batteries need to be maintained within a fairly narrow temperature band.

To get around this, “thermal conditioning” is used to regulate battery temperature. In cars such as the Fisker Karma and the Holden Volt, that means using liquid coolant. For use in colder climates, battery heating can be required.

While liquid cooling or heating is effective, it also adds an extra layer of complexity - and therefore cost - to electric cars that a more robust battery pack wouldn’t require.

Now, battery-manufacturer A123 Systems believes that it has invented the top performer of the lithium-ion battery world.

Their new technology is called Nanophosphate EXT (EXtreme Temperature) and A123 is claiming that the lithium-ion variant can operate at both high and low temperatures without requiring conditioning.

Jeff Kessen, A123’s director of global marketing for the Automotive Solutions group said, “We feel that we have erased the cold cranking deficit - the Achilles heel for Li-ion from a performance perspective against lead acid.”

Tests run by Ohio State University’s Center for Automotive Research appear very promising.

The Nanophosphate EXT cells retain more than 90 percent of their energy capacity after 2,000 full charge-and-discharge cycles conducted at 45 degrees Celsius.

Testing in extreme cold suggests the new cells will deliver 20 percent more energy than conventional cells at -30 degrees C. This better power delivery implies they could be used to create smaller, lighter batteries for both electric and conventional cars.

Professor of Engineering at Ohio State University, Dr Yann Guezennec, said the Nanophosphate EXT cells were “unlike anything we’ve ever seen from lead acid, lithium ion or any other battery technology.”

The new technology is expected to greatly improve the cold-cranking capabilities of A123's lithium ion 12V engine starting batteries. This would eliminate the main performance advantage of lead acid batteries, with a lighter, longer-lasting alternative to absorbent glass mat (AGM) and other lead acid batteries.

A breakthrough would be good news for A123 Systems. The battery maker suffered a recall of its battery packs in the Fisker Karma in March, and gasses from A123 cells being tested sparked an explosion at GM’s Battery Lab, injuring several workers.

Nanophosphate EXT technology is expected to start volume production in 20Ah prismatic cells in the first half of 2013.

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