US road safety watchdog decides against probe into Tesla battery fires

Automaker accused of using software to cover up defects. Regulator says non-crash blazes are 'rare events'

America's National Highway Traffic Safety Administration on Monday denied a request to investigate the safety of Tesla’s electric car batteries following a series of vehicle fires in 2018 and 2019.

A man named Edward Chen filed a petition in September 2019 urging the regulator to launch a probe into Tesla’s vehicles to see if there were any defects in the products. He claimed the automaker had that year issued “over-the-air software updates to mask and cover-up a potentially widespread and dangerous issue with the batteries in their vehicles.” The update reduced battery capacities and fast-charging rates.

As evidence that the cars had a battery-related defect that the software was papering over – by throttling the charging process, for example – Chen cited the case of two Tesla Model S cars, one on the Chinese mainland and the other in Hong Kong, that burst into flames in 2019 after using supercharger points, which speed up the process of charging the car's battery. With the mainland fire, no root cause was identified, though the finger was pointed at the frequency of fast-charging and temperature of the hardware. For the Hong Kong one, the batteries had recently been repaired.

Chen also cited three blazes involving the same Tesla model that occurred in the US as well as one in Germany. The NHTSA analyzed the accidents, and concluded the fires outside of China were not related to the batteries and supercharging. And so it's not going to do anything about the complaint.

“While a pattern of fires occurring shortly after completing supercharging sessions was observed in China, no similar fire incidents have been identified in the United States,” the NHTSA’s report [PDF] said.

According to the agency, Tesla said it was not aware of any non-crash "battery fires associated with fast charging in the United States or any other country" other than those two in China.

“Given the absence of any incidents in the United States related to fast charging," the administration stated, "and the absence of any such incidents globally since May 2019, it is unlikely that an order concerning the notification and remedy of a safety-related defect would be issued due to any investigation opened as a result of granting this petition.

“Therefore, upon full consideration of the information presented in the petition, and the potential risks to safety, the petition is denied.”

Of the three fires in California, one in West Hollywood involved a Tesla Model S that had never been fast charged; one in Los Gatos wasn't frequently supercharged and had later-generation power cells that were out of scope of the complaint plus Tesla could not rule out physical damage to the batteries; and one in San Francisco that was caused by the rear drive unit. The fire in Ratingen, Germany, was thought to have been caused by something other than the battery pack.

Tesla sold about 225,000 Model S and Model X vehicles in the United States between 2012 and 2019, the report stated. Approximately 62,000 of those cars supported the firmware update that limited the car’s battery life. Only 2,062 vehicles – 3.5 per cent – had enabled the update.

In other words, there doesn't seem to be much of a case, here. "The available data indicate that non-crash battery fires in Tesla vehicles are rare events," as the watchdog put it.

Chen has also filed a series of class-action lawsuits over the Tesla fires in California. ®