Original URL: http://www.theregister.co.uk/2011/11/28/us_highway_safety_agency_opens_formal_probe_into_chevy_volt_batteries/

Car safety agency sparks e-car battery probe

GM Volt under scrutiny after post-prang fires

By Tony Smith

Posted in Science, 28th November 2011 14:37 GMT

Two further Chevy Volt lithium-ion batteries have caught fire during tests carried out by the US National Highway Traffic Safety Administration after a separate crash-test Volt's battery burst into flames more than three weeks after the impact.

The NHTSA said it was formally opening a safety defect investigation as a result.

The organisation said that its exploration of the e-car safety concerns raised by the first fire involved three further impact tests designed to damage Volt battery packs to the same degree as the one in the first test and "to simulate a real-world, side-impact collision into a narrow object such as a tree or a pole followed by a rollover".

The original impact test, conducted in May 2011, damaged the battery itself and ruptured the hose feeding it with coolant.

"Following a test on 16 November that did not result in a fire, a temporary increase in temperature was recorded in a test on 17 November," said the NHTSA team.

"During the test conducted on 18 November… the battery pack was rotated within hours after it was impacted and began to smoke and emit sparks shortly after rotation to 180 degrees. Yesterday, the battery pack that was tested on 17 November… caught fire at the testing facility."

The agency said it knows of no instances of Volt crashes that have resulted in battery fires, and neither have prangs involving other e-cars fitted with li-ion batteries.

However, because this months tests were explicitly designed to replicate the kind of crash such cars might experience in the real world, the agency had no choice but to formalise the investigation.

The NHTSA said it was too early to say whether the probe will lead to a recall of Volt batteries.

The agency has already awarded the Volt a five-star NCAP safety rating, as has its European equivalent. The NHTSA said General Motors, which produces the Volt, was co-operating with its investigation. ®