Car safety car battery

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".