Tesla to NHTSA: Investigate Our Model S FiresTesla to NHTSA: Investigate Our Model S Fires

The National Highway Traffic Safety Administration (NHTSA) said today it is opening an investigation to examine the potential risks associated with "undercarriage strikes" on Tesla's Model S electric cars.

In a web posting, NHTSA's Office of Defects Investigation (ODI) said it is opening the investigation in response to two incidents -- one in Washington and another in Tennessee -- in which vehicles struck metallic objects that led to thermal runaway. The posting described the problem as "Deformation/intrusion into the propulsion battery."

NHTSA's announcement came just hours after a blog post by Tesla CEO Elon Musk saying that the company is making changes in response to the recent fires. He said the company will make an "over-the-air" software update to Model S air suspension systems to provide higher ground clearance at highways speeds. The company will also amend its warranty policy to cover damage due to a fire, even in cases of driver error. Finally, Musk said Tesla had requested that NHTSA undertake a full investigation into the fires.

A statement from NHTSA, however, offers a different view of the events. "NHTSA's decision to open any formal investigation is an independent process," the statement read. "In regards to Tesla, the agency notified the automaker of its plans to open a formal investigation and requested their cooperation, which is standard agency practice for all investigations. The automaker agreed to do so."

In his posting, Musk again made a case for the safety of electric vehicles, emphasizing the fact that gasoline-powered cars are far more dangerous:

He added that the firewalls made it possible for the driver in the Tennessee fire to retrieve pens and papers from the glove compartment before exiting the vehicle.

The two recent Model S incidents that occurred in the US involved vehicles striking metallic objects. The first, near Seattle, happened after a driver rolled over a curved piece of metal. The second, in Tennessee, occurred after a Tesla owner hit a trailer hitch on an Interstate highway.

After the accidents, experts told Design News that there were two possible failure mechanisms. The metallic objects could have deformed the battery casing, causing short-circuiting and thermal runaway. Or the metal could have punctured the batteries, causing spillage of electrolyte, which might have been ignited by nearby sparks.

Although the recently announced fixes may improve the safety of the lithium-ion packs, experts have said that the designers couldn't be faulted in those incidents. "There's no such thing as absolute perfection," David Cole, chairman emeritus of The Center for Automotive Research, told us after the October fire. "As a designer, you just hope you can get fairly close to it."

Related posts: