New research into electric vehicle (EV) fires has found they behave similarly to conventional vehicle fires in several key areas, although battery thermal runaway continues to present unique challenges for firefighters, and toxic exposures remain a concern.
UL Research Institutes conducted full-scale fire experiments involving 18 vehicles, including nine free-burn tests and a further nine EV tests examining different firefighting techniques. The EVs used in the tests were fully charged.
During the burns, researchers found EV and internal combustion engine (ICE) vehicle fires produced broadly similar fire growth rates, peak fire sizes and burn durations. EVs released more total energy on average, which the researchers linked primarily to their higher vehicle mass – EVs usually weigh between 10-30 per cent heavier than their ICE counterparts.
The study also found water remains an effective tool for managing an EV fire. It can suppress burning within the cabin, protect surrounding exposures and control flames associated with the battery while thermal runaway runs its course.
However, none of the suppression techniques tested could stop thermal runaway once it had started. Attempts to directly cool or extinguish the battery are also discouraged, as its position and vehicle construction can make effective access difficult.
Adding a suppression agent to water also provided no meaningful advantage over using water by itself, according to the study.
Fire blankets were also assessed. While they reduced visible flames, the study found potentially flammable gases could build beneath the blanket, creating an explosion risk. Researchers consequently recommend against their use indoors or in tight environments.
The report also identified ongoing contamination concerns. Elevated levels of some metals and particulate fluoride associated with battery fires were detected in smoke and firefighting runoff, while contamination was also recorded on protective equipment.
Researchers recommend firefighters continue wearing full protective equipment and breathing apparatus throughout an incident, including during the overhaul stage, due to toxic exposure and potential reignition risks. Further research into air, water, surface and protective-equipment contamination is continuing, with additional research expected to uncover more guidance over the next year.
Importantly, the findings will contribute to a new EV firefighting course planned for release through FSRI’s Fire Safety Academy later in 2026.
