U.S. auto safety officials have launched a probe into the safety of electric vehicle batteries after a Chevrolet Volt caught fire weeks after being crash tested.
The probe first reported by Bloomberg News is the broadest investigation so far by the National Highway Traffic Safety Administration into the safety of the lithium-ion batteries used in electric vehicles such as the Volt and the Nissan Leaf -- and the same types of batteries expected to power most upcoming EVs and hybrids in the next several years.
NHTSA said in a statement that the fire happened more than three weeks after the Volt was subjected to a side-impact test -- one where it was smashed into a pole at 20 mph. The fire caused some property damage but no injuries; the Volt received a five-star score for occupant safety in the test.
The agency asked every automaker which either has an EV for sale or plans to bring one to market -- including General Motors, Nissan, Ford, Toyota and others -- to explain their procedures for disposing of batteries following a crash, and for tips that might avoid fires or other dangers for tow-truck operators, first responders and anyone else who works with crashed vehicles.
"NHTSA does not believe the Volt or other electric vehicles are at a greater risk of fire than gasoline-powered vehicles," the agency said in a statement. "It is common sense that different designs of electric vehicles will require different safety standards and precautions."
GM spokesman Greg Martin said the company and NHTSA investigated the fire and attempted to recreate it, but were unable to, and that no other crash-tested Volts have caught fire.
"We've subjected the Volt's battery pack alone to 300,000 hours of testing, and we've developed a strong set of safety protocols for battery discharge, handling and disposal," Martin said. "Had those protocols been applied after crash test, this wouldn't have happened."
The case marks the first fire linked to the Volt since it went on sale last December; a house fire earlier this year involving a garage where a Volt was charging was found to have been sparked by faulty wiring. Another recent garage fire with a Volt in North Carolina remains under investigation.
Lithium-ion batteries are generally more stable than traditional car batteries, and can withstand damage such as punctures without sparking or catching fire. But larger electric vehicles such as the Volt and Nissan Leaf carry far more powerful battery packs than hybrids such as the Toyota Prius. Before the Volt was launched, GM conducted several clinics with fire departments and paramedics on how to handle Volt crashes, including how to unplug its batteries and the location of high-voltage wires.