The spontaneous combustion of faulty Tesla lithium-ion batteries caused a large, early morning fire at two car dealerships in Palo Alto last August, according to two recently released fire inspection reports.
The batteries, which were stored in wooden crates in an outside storage area, accidentally ignited, burning a nearby Ford F-250 truck and destroying a mobile-office building, according to reports by the Santa Clara County Fire Investigation Task Force and the Palo Alto Fire Prevention Bureau, which was the lead investigative agency. The Bureau of Alcohol, Tobacco, Firearms and Explosives also assisted with the investigation.
A chemical reaction from an unknown failure within a cell of one of the Tesla batteries created an increase in internal temperature, which ignited flammable electrolyte fluid within the battery. That heat ignited surrounding cells, which in turn set the wooden crates ablaze, the reports found.
“These batteries contain no free lithium metal but do contain lithium ions and highly flammable electrolytes,” the Santa Clara County Fire report stated. “Lithium batteries are capable of spontaneous ignition and subsequent explosion from overheating. Internal failures may be caused by electrical shorting, rapid discharge, overcharging, manufacturers’ defect, poor design, or mechanical damage, among many other causes.
“Overheating of these batteries results in a process called thermal runaway, which is a reaction within the battery causing internal temperature and pressure to rise at a quicker rate then can be dissipated,” the report continued.
“Once one battery cell goes into thermal runaway, it produces enough heat to cause adjacent battery cells to also go into thermal runaway. This event produces a fire, which repeatedly flares up as each battery cell in turn ruptures and releases its contents. The result is the release of flammable electrolyte from the battery,” the county’s report noted.
The fire began on Aug. 7, 2022, at about 5:30 a.m. in an outside storage area of the Tesla dealership and service center located at 4180 El Camino Real, near Arastradero Road, according to the Palo Alto Fire report.
Twelve batteries in wooden crates had been placed along a chain link fence, with the McLaren/Volvo dealership to the east of the fence at 4190 El Camino Real. Video footage from the McLaren/Volvo dealership and from Tesla confirm the location of the fire’s origin, according to the Palo Alto report.
The fire quickly spread to engulf the Ford truck that was parked north of the batteries and to seven crates of Tesla Roadster batteries, which were to the south along the fence. Once started, the fire jumped to a mobile-office building located at the McLaren/Volvo dealership along the fence. The trailer and the batteries were less than 5 feet away from each other across the property line.
As a result of the fire, several of the individual cells of the batteries sustained structural damage and catastrophic failures; some individual cells exploded, shooting into the McLaren lot, the Palo Alto fire report noted.
The Ford truck was left with major damage. Fire patterns indicated the blaze moved toward the vehicle and that it was not the origin of the fire, the Santa Clara County report noted.
The mobile office also suffered structural and interior damage, and the heat from the fire caused the roof to collapse, the reports noted.
The fire caused damage of about $300,000.
Fire inspectors ruled out other potential causes of the fire, including electrical, nearby mechanical equipment and weather. There were no indications of a break-in at either of the properties and no evidence of incendiary devices, the report noted.
Tesla sent its own team to investigate the fire. According to the Palo Alto Fire report, Tesla stated that it “could not rule out mechanical damage, cell spontaneous runaway, or preexisting critical damage to the pack as a root cause” and considered the cause of the fire to be “undetermined.”
Two firefighters were injured by toxic-fume inhalation and another injured their knee. One of the firefighters was transported to Stanford Hospital’s emergency department for evaluation. Another firefighter sought medical care after the incident, according to the Palo Alto inspection report.
An employee at the Palo Alto Tesla showroom on Friday, April 14, referred this news organization’s questions to the corporate office, which did not immediately respond to a request for comment.
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