Tesla Semi fire required 50,000 gallons of water to extinguish

California firefighters needed to spray 50,000 gallons of water to extinguish a roadside Tesla Semi fire, the US National Transportation Safety Board (NTSB) announced in a preliminary report. Crews also used an aircraft to drop fire retardent in the "immediate area as a precautionary measure," according to the agency.

The crash happened at 3:13 AM on August 19 on the I80 freeway east of Sacramento. The tractor-trailer departed the roadway while navigating a curve, struck a traffic delineator and eventually hit a tree. The driver was uninjured but taken to hospital as a precaution.

The Tesla Semi's large 900kWh battery caught fire and reached a temperature of 1,000 degrees F while spewing toxic fumes. It continued to burn into the late afternoon as firefighters dowsed it with water to cool it down (Tesla sent a technical expert to assess high-voltage hazards and fire safety). It wasn't until 7:20 PM (over 16 hours after the crash) that the freeway was reopened.

All of that caught the attention of the NTSB, which sent a team of investigators, mainly to examine the fire risks posed by large lithium-ion battery packs. The agency — which can only make safety recommendations and has no enforcement authority — said that "all aspects of the crash remain under investigation while the NTSB determines the probable cause."

Given the long road shutdown time, dangerously hot fire and toxic fumes, the accident is likely to provoke a lot of discussion in and out of government. The NTSB concluded in 2021 that battery fires pose a risk to emergency responders and that manufacturers' guidelines around such fires were inadequate.