The National Highway Traffic Safety Administration (NHTSA) put the batteries of the plug-in hybrid Volt under the microscope earlier this month after crashworthiness tests in May led to a Volt setting itself on fire more than three weeks after it was crash-tested.
NHTSA tested three lithium-ion battery packs from the Volt between November 16 and 18 – in all three cases intentionally damaging the battery compartment and rupturing the vehicle’s coolant line. The first vehicle tested did not result in a fire but showed a temporary temperature increase the following day. The second Volt (tested on November 17) was monitored daily and caught fire at the testing facility seven days later. The third vehicle began to smoke and emit sparks within hours of being crash tested and rotated.
In all three instances, the Volt’s battery was impacted and rotated to simulate a real-world side-impact collision with a narrow object (like a tree or pole) followed by a rollover.
NHTSA is working with General Motors, the Department of Energy and the Department of Defense to assess the cause and implications of the fires.
NHTSA says it is too soon to know whether the investigation will lead to a recall of any vehicles or parts, but insists if it identifies any unreasonable risk to safety it will take immediate action to notify customers and ensure GM takes an acceptable course of action.
The authority is working with all vehicle manufacturers to ensure they have appropriate post-crash protocols for motorists, emergency services, tow truck drivers and scrap yard operators.
GM has a protocol that states the batteries of it electric vehicles should be depowered after a significant crash, although at this stage NHTSA says this is a job best left to qualified Chevrolet employees.
So far, NHTSA testing has not raised concerns about any battery-powered vehicles other than the Chevrolet Volt. It says it is not aware of any crashes that have resulted from battery-related fires in the Volt or any other vehicles powered by a lithium-ion battery.
The announcement of the investigation comes just days after the Chevrolet Volt was awarded the maximum five-star safety rating from Euro NCAP, a result that mirrored NHTSA’s own five-star rating of the Volt in June.
The Holden Volt (a rebadged version of the Chevrolet) will go on sale in Australia in the final months of 2012.