NHTSA to not open legal investigation into Tesla’s battery management software

It was recently announced that the National Highway Traffic and Safety Administration has rejected a petition to open a formal investigation into Tesla’s battery management software.

Indeed, the petition was based on allegations that an over-the-air update was defective and caused fires in five vehicles. The agency refused to open an investigation due to the fact that these incidents happened outside of the United States and that none of these were related to crashes and most vehicles were parked.

Moreover, the agency reviewed 59 complaints out of the total 61,781 Model S and Model X vehicles from 2012 to 2019 before it rejected the petition. 52 of these were alleged reductions in battery capacity and seven alleged reductions in charging speed after the software was updated. Besides, it was found out that the updates helped restore some or all battery capacity to those vehicles.

Two of the fires were caused by a storm in China in 2019 after the batteries were at a high state of charge and were parked with the battery cooling systems shut off. Hence, the cause of these issues is very likely physical defects from manufacturing or physical damage in the course of use.

Two fires happened in the US but one vehicle had no Supercharging history and the other couldn’t be linked back to the high-voltage battery system. The fifth fire occurred in Germany to a vehicle that was parked at a low state of charge for an extended period of time.

Since there was no incident in the US due to fast charging, and no incidents since May 2019, there was no reason to go through with the petition. However, the agency is still moving forward with its investigation into Tesla’s Autopilot software after certain cars that were using the advanced driver assistance system crashed into 12 parked first responder vehicles with flashing lights, leading to 17 injuries and one death since 2018.