We’ve learned from years of seeing defective laptops and smartphones that lithium-ion batteries can be extremely hazardous when they’re damaged. And those batteries are tiny. The massive lithium-ion slabs in Tesla’s electric vehicles are potentially much more dangerous in the event of a crash or defect. Tesla is still on the defensive after a March Model X crash that claimed the life of the driver, and now a safety report from the Mountain View fire chief on that incident has added fuel to the fire.
Tesla maintains the crash was the driver’s fault, and it’s been remarkably open about this stance. It even released information about the accident that would usually be kept under wraps until after the NTSB investigation. The vehicle was in Autopilot mode when it struck a concrete barrier on March 23rd. Tesla has long maintained that drivers need to be ready to take the wheel at any moment in Autopilot mode, and in this case, it appears that the car incorrectly detected lane markers and drove straight into a concrete divider. It’s unclear why the car didn’t identify the obstacle and apply the brake automatically.
According to Mountain View fire chief Juan Diaz, putting out the resulting fire was no simple feat. A Tesla Model X can have as much as 100 kWh of power, and it can all be released as heat in the event of an accident. Firefighters on the scene initially believed they had extinguished the fire in about two minutes, but the interior of the battery still suffered from thermal runaway. It actually continued to smolder and reignite throughout the day.
Even after the car was removed from the highway, it continued to pose a danger. Investigators had to call Tesla engineers to come and dismantle the damaged battery after it ignited several more times over several days. After taking the battery apart, individual cells still overheated and caught fire up to six days after the crash.
Tesla offers online training for first responders to learn how they should deal with lithium-ion battery fires. It also notes that it has designed its batteries in such a way that fires spread slowly and allow occupants time to leave the vehicle. In the March crash, the impact killed the driver, not a damaged battery.
There’s not much Tesla can do about the nature of lithium-ion batteries, and it’s not like gasoline isn’t flammable. It may be forced to make changes to Autopilot, though.