18 EV Fires Later, Here’s What The Data Says About Which Scenarios Are Actually Most Dangerous
A major new study from UL Research Institutes’ Fire Safety Research Institute cuts through years of fear-driven headlines about electric vehicle fires and replaces them with controlled-burn data. Released this week, the report — built on 18 full-scale EV fire experiments — finds that battery fires are a serious but manageable hazard, one that existing equipment and trained crews can handle without reinventing the firefighting playbook.
The research team ran nine free burns to establish a baseline comparison between EVs and gas-powered vehicles, then burned nine more EVs to test how different suppression tactics performed once a battery pack was fully involved. Every vehicle was fully charged before ignition. Fires were started with a propane burner and left to grow for six minutes before suppression began — a delay chosen to mirror realistic fire department response times across North America.
EV and Gas-Car Fires Behave More Alike Than You’ve Been Told
The free-burn data challenges one of the most persistent assumptions in EV safety coverage: that battery fires are a fundamentally different, more volatile hazard than fires in internal combustion vehicles. According to the study, EV and gas-car fires tracked closely in fire growth rate, peak fire size, and overall fire duration.
EVs did release more total energy on average — but researchers attributed that difference to vehicle mass, not to any unique property of battery combustion. Heavier vehicles carry more stored energy in their structure, fluids, and materials; the battery chemistry itself is not the primary driver of a larger energy release. That distinction matters for how buyers and fleet operators should think about risk.
What Water Can Do — And What Nothing Can Do Once Thermal Runaway Starts
The report is direct about the limits of suppression once a battery is in thermal runaway: nothing stops it. None of the tactics tested — water alone, fire blankets, or water combined with a supplemental suppression agent — was able to halt thermal runaway once it had begun. The water-plus-agent combination showed no meaningful advantage over plain water.
What water does accomplish is significant, though. For most incidents, a standard hose stream remains the right tool for suppressing the cabin fire, limiting crew and bystander exposure, and controlling visible flaming while the battery works through thermal runaway on its own timeline. The report also notes that directly cooling or extinguishing the battery pack itself is not recommended — and is largely precluded by how modern EVs are built, with packs sealed low in the vehicle structure.
Fire Blankets Help, But They Carry a Real Explosion Risk
EV fire blankets have gained traction among fire departments as a containment tool, and the study confirms they do control visible flaming effectively. The caution is equally clear, however. Flammable gases can accumulate underneath a deployed blanket, and in a confined space — a parking garage, an enclosed bay — those gases can reach concentrations that create a deflagration hazard.
The research team recommends against repositioning a blanket once it has been placed, and advises strongly against using blankets indoors or in any confined environment. Most importantly, blankets should never be treated as a substitute for water-based suppression. They are a supplement, not a replacement — a point the report and a parallel safety advisory from the U.S. Fire Administration both emphasize.
Full PPE Throughout, and Decontamination Data Still Coming
One of the study’s most operationally significant recommendations is that full personal protective equipment and self-contained breathing apparatus should stay on for the entire incident, including overhaul — the post-suppression phase when crews typically move through a scene. Reignition risk persists long after visible flames are out, and toxic exposure does not end when the fire does.
Researchers documented elevated concentrations of metals and particulate fluoride tied to the battery fire, showing up in smoke, in suppression runoff water, and on firefighters’ turnout gear. Much of the contamination traces back to the passenger compartment fire itself, but the battery adds a distinct chemical layer. Full decontamination data — covering air, surface, water, and PPE — is still moving through peer review and final analysis, with publication expected to roll out over the coming year. This study is ongoing, not a closed chapter.
For buyers and fleet operators, the takeaway is reassurance grounded in data rather than anecdote. Battery fires are serious. They are also manageable — with training, familiar equipment, and a clear understanding of where the battery changes the environment crews are walking into. The research team has also developed an EV Fire Tactical Decision Aid, a step-by-step fireground framework, which will feed into a new EV firefighting course at the Fire Safety Academy expected to launch later this year.
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