California firefighters had to douse a flaming battery in a Tesla Semi with about 50,000 gallons (190,000 liters) of water to extinguish flames after a crash, the National Transportation Safety Board said Thursday.
In addition to the huge amount of water, firefighters used an aircraft to drop fire retardant on the “immediate area” of the electric truck as a precautionary measure, the agency said in a preliminary report.
Firefighters said previously that the battery reached temperatures of 1,000 degrees Fahrenheit (540 Celsius) while it was in flames.
The NTSB sent investigators to the Aug. 19 crash along Interstate 80 near Emigrant Gap, about 70 miles (113 kilometers) northeast of Sacramento. The agency said it would look into fire risks posed by the truck’s large lithium-ion battery.
I read in a firefighter’s thread that the trick is to use a low pressure spray directly on the battery compartment. (It was a thread about Tesla cars not semis though so that might not apply)
The reason was you can’t actually put the fire out, it’s self oxidizing (it can literally burn underwater) so you basically need to wait till it burns itself out. Fortunately batteries only hold something like 1/10th the energy of gasoline and can’t release that energy as quickly so a fine light spray is enough to keep it from getting hot enough to catch anything else on fire including batteries in the surrounding battery modules.
Takes a long time, like hours to get it to a point they can move the vehicle and literally a couple weeks before the reaction completely fizzles out. They have special lots they tow them to where the car can fizzle itself out without damaging anything surrounding it.