The recent Los Angeles protests, ignited by escalating tensions over federal immigration policies, took a disturbing turn when several Waymo robotaxis became targets of arson. But what transpired wasn’t just the typical vehicle fire; it was a spectacle of complete obliteration, leaving onlookers stunned and raising serious questions about the safety of lithium-ion batteries in electric vehicles.

Eyewitnesses described scenes where Waymo-branded Jaguar I-Pace robotaxis, symbols of technological advancement and corporate surveillance in the eyes of some protesters, were consumed by flames so intense that the very asphalt beneath them began to melt and buckle. When the smoke cleared, the vehicles were reduced to little more than skeletal remains – wheel rims and the faintest traces of aluminum. This wasn’t just fire; this was vaporization.

The culprit behind this automotive apocalypse is a phenomenon known as « thermal runaway. » To understand this, we need to delve into the heart of these electric vehicles: their batteries. The Jaguar I-Pace, like many EVs, houses a substantial amount of stored chemical energy – approximately 90 kilowatt-hours, comparable to the explosive power of about 170 pounds of TNT. This energy is meticulously packed within hundreds of lithium-ion pouch cells. These cells are essentially energy sandwiches: flammable electrolytes sandwiched between thin polymer films, as delicate as the plastic of a snack bag. A puncture, overheating, or, in this case, the introduction of an incendiary device, sets off a catastrophic chain reaction.

When a single cell is compromised, it generates more heat than it can dissipate. This heat then spreads to neighboring cells, triggering a domino effect of escalating temperatures. This is the essence of thermal runaway: a positive feedback loop of destruction. A 2024 study in the Journal of Power Sources revealed that battery temperatures during thermal runaway can exceed a staggering 1,000 degrees Celsius. At this point, the battery pack effectively transforms into its own self-sustaining furnace.

What happens next is a material scientist’s nightmare. Aluminum components of the car’s floor liquefy at around 660 degrees C, weakening the entire undercarriage. Magnesium parts – seat frames, steering column brackets, even the beam behind the dashboard – ignite with a blinding white flare. Plastics vaporize, tires disintegrate, and even the sophisticated LIDAR (Light Detection and Ranging) mast on the roof melts into a grotesque, overcooked marshmallow.

Studies in Fire Technology (2025) and Applied Energy (2023) have highlighted the role of the « skateboard architecture » – the placement of the battery pack in the floor of the vehicle. This design choice, while optimizing space and handling, makes the floor the epicenter of the inferno, radiating flames upwards and outwards, cooking everything above it.

But the fiery spectacle is not the only danger. As the battery burns, it releases hydrogen fluoride (HF), a highly toxic gas documented in laboratory tests. HF is a potent respiratory irritant and can cause severe lung damage. Disturbingly, images from the Los Angeles protests showed individuals standing near the burning Waymos, oblivious to the invisible threat. Historically, first responders have experienced throat burns and breathing difficulties when arriving at scenes involving burning lithium-ion batteries. Depending on the concentration of HF, exposure can lead to coughing up blood within minutes. Concentrations above 30 parts per million (ppm) are immediately dangerous, and 50 ppm can be fatal within 30 to 60 minutes, according to the CDC. Measurements taken near EV fires have recorded peaks of 150 to 450 ppm, with sustained levels often hovering around 50 ppm. Firefighters dread these “battery box fires,” finding that flame-retardant foams are largely ineffective.

The preferred method for extinguishing a thermal runaway battery is overwhelming it with water – typically 30,000 to 40,000 gallons, at least 40 times the amount needed for a gasoline car fire. If the fire isn’t completely quenched, the stranded energy can reignite hours later, a hazard flagged by the National Transportation Safety Board in a 2020 report.

While car manufacturers are implementing safety measures like software monitoring and charging limitations, these measures have their limits. In 2023, Jaguar recalled over 6,400 I-Pace vehicles after multiple battery fires, likely caused by manufacturing defects. And as the Los Angeles Times reported, software is helpless against a “makeshift flamethrower.”

It’s important to note that these fiery images do not necessarily indicate that electric cars are inherently dangerous. A 2023 Finnish study showed that EVs catch fire less often than gasoline cars on a mile-for-mile basis. However, when an EV does burn, the physics change dramatically. You are no longer fighting a fuel spill, but an energy-dense, metal-oxide battery determined to finish its destructive course, and a single Molotov cocktail can transform a robotaxi into a pool of molten alloy.

Cet article a été fait a partir de ces articles:

https://www.scientificamerican.com/article/why-the-waymo-car-fires-in-recent-los-angeles-protests-caused-the-robotaxis/, https://www.scientificamerican.com/article/how-the-mathematics-of-honesty-underlies-these-auctions/, https://www.scientificamerican.com/article/how-to-protect-yourself-from-recent-salmonella-outbreak-in-recalled-eggs/, https://www.scientificamerican.com/article/a-mysterious-kidney-disease-epidemic-is-killing-thousands-of-young-men-whats/, https://www.scientificamerican.com/article/a-blockbuster-muon-anomaly-may-have-just-disappeared/