Third Tesla fire prompts battery safety inquiry demands

A third fire involving Tesla's Model S has prompted renewed calls for a full investigation into the electric car's safety, after the award-winning EV caught alight following a crash earlier this week. The incident, in Smyrna, Tennessee, saw the Model S hit a tow hitch in the middle of a lane on the highway, a spokesperson from Highway Patrol told Bloomberg, in the process "damaging the car's undercarriage and causing the fire."

The issue has already spurred calls by automotive safety advocates to launch a full federal investigation into Tesla and the construction of the Model S. "It appears there's inadequate shielding on the bottom of these vehicles," Center for Auto Safety executive director Clarence Ditlow said this week. "Road debris is a known hazard to the undercarriage of vehicles."

A previous accident in Seattle back in October was also blamed on road debris, though Tesla founder Elon Musk later argued that it was a freak incident.

"The geometry of the object caused a powerful lever action as it went under the car, punching upward and impaling the Model S with a peak force on the order of 25 tons" Musk wrote after the company investigated the incident. "Only a force of this magnitude would be strong enough to punch a 3 inch diameter hole through the quarter inch armor plate protecting the base of the vehicle."

Despite that quarter inch protection, which is layered over the 1,000 pound power pack that powers the Model S, a piercing to the battery is believed to be the cause of this latest fire in Tennessee. Ditlow has demanded that the National Highway Traffic Safety Administration (NHTSA) look at the overall safety of the electric cars as a result.

The NHTSA had declined to investigate the Seattle fire, the LA Times reports, deciding that the issue had been caused by the accident not an inherent problem with the car itself. "After reviewing all available data, the NHTSA has not found evidence at this time that would indicate the recent battery fire involving a Tesla Model S was the result of a vehicle safety defect or non-compliance with federal safety standards" the NHTSA concluded at the time.

As for the most recent incident, the agency "will contact the local authorities who are looking into the incident to determine if there are vehicle safety implications that merit agency action" spokesperson Karen Aldana said this week.

Meanwhile, Tesla says that its investigation will begin imminently, and argues that the Model S' driver in fact credits the car with keeping him alive. "We have been in contact with the driver, who was not injured and believes the car saved his life" a spokesperson said. "Our team is on its way to Tennessee to learn more about what happened in the accident. We will provide more information when we're able to do so."

An NHTSA investigation completed back in January into the Chevrolet Volt found that GM's electric car was not a greater fire risk than a traditional gas-powered model, concerns around battery piercing having been raised during crash testing. The Model S notably scored the highest ever rating in the NHTSA's safety tests.