The 2011 and 2012 Chevy Volt's have five-star crash ratings from the NHTSA. A series of fires either directly or indirectly involving the Chevy Volt are causing some to cast doubt upon the Volt. Bloomberg News revealed today that in May a Chevy Volt caught fire at an NHTSA testing facility three weeks after being crash tested, and that "regulators are scrutinizing the safety of lithium-ion batteries".
The Volt in question caught fire while in a storage yard at an NHTSA testing facility in Wisconsin. Three weeks earlier the car had been in a side impact crash test, then undergone some post-crash processing. It passed the test and its battery pack caught fire while in storage. Both GM and the NHTSA crash tested more Volts in June and could not replicate the fire.
“I want to make this very clear: the Volt is a safe car,” Jim Federico, GM’s chief engineer, said. “We are working cooperatively with NHTSA as it completes its investigation. However, NHTSA has stated that based on available data, there’s no greater risk of fire with a Volt than a traditional gas-powered car.” Gasoline powered cars routinely catch fire, with 250,000 or more car fires per year and perhaps one human death per day in car fires.
There have been no fires reported among the 8,000 Nissan LEAF's on the road. Likewise Tesla Roadsters have a history of 16 million miles with no post-crash fires.
At the same time the potential for lithium battery fires is one factor behind the long R&D period between their initial development in the 1970's, and their widespread adoption in vehicles. Spend enough time around battery engineers and you learn the phrase "thermal runaway", and look in the right corners of the Internet and you can find videos of lithium battery fires. However, do those facts mean electric vehicle batteries are unsafe? Not necessarily. Battery and vehicle designers know about these issues and design battery management systems into their cars to mitigate the danger, and they choose safer battery chemistries. Remember that we routinely drive around with vehicles carrying 20 gallons or more of a highly explosive liquid fuel. The fact that we can do so with a high degree of safety demonstrates the automobile manufacturers know how to design safe vehicles.
“Lithium burns really hot, but it doesn’t happen often. You have to do something pretty dramatic to make it catch fire” said Sandy Munro, president of Munro and Associates
GM's Volt is using cells manufactured by Compact Power (a subsidiary of LG Chem) that are thought to be either a lithium manganese spinel chemistry, or nickel manganese cobalt. Both chemistries are regarded as being very safe.
GM believes the Volt is safe, and that the NHTSA did not follow standard protocols after the crash test, including de-activating the battery pack.
Until Bloomberg broke the news today the NHTSA had not disclosed the fire, nor that they were working with auto manufacturers seeking information about EV battery packs.
Officials with the NHTSA and Energy Department are planning to test battery modules from other Volt's used in crash testing. So far nobody has been able to replicate the one fire, and hope to see if they can replicate the conditions which led to this fire.
See:
GM Volt Fire Prompts Probe of Lithium Batteries
GM Statement in Response to NHTSA Investigation
Chevy Volt crash test results performed by Insurance Institute for Highway Safety
GM defends Volt's safety after NHTSA reports fire after crash test
Chevy volt fire at NHTSA crash testing facility in Wisconsin - initial reporting
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