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Electric vehicle (EV) fire safety has become one of the most urgent topics facing first responders, automakers, and engineers. As EV adoption grows, so does concern over high-voltage battery fires—events that pose complex, prolonged risks due to thermal runaway. In a recent high-profile initiative, Munro & Associates partnered with the UL Fire Safety Research Institute to explore real-world electric vehicle fire suppression strategies. This joint effort culminated in a controlled burn of a Tesla Model 3, offering unprecedented insight into how EV battery packs react to heat, fire suppression, and post-burn diagnostics.
This intensive EV battery fire training is part of a three-year project designed to evaluate how electrification alters vehicle fire behavior and how standard firefighting tactics must adapt. The results could influence global best practices for EV safety.
Why Controlled Burns Matter
The experiment took place inside a UL laboratory north of Chicago. The goal: simulate fire department response to an EV fire using common suppression tools and techniques. With a Tesla Model 3 as the test subject and a Ford Mach-E scheduled next, UL and Munro aimed to capture data on ignition, propagation, suppression, and post-fire diagnostics.
To benchmark against internal combustion engine (ICE) fires, researchers had already burned gas-powered vehicles in earlier phases. The objective was to compare fire size, heat output, material emissions, and time to full ignition.
Using a propane “turkey fryer burner on steroids,” researchers ignited thermal runaway in the Tesla’s 18650 cell-dense battery pack. These cells, once ignited, undergo rapid propagation, generating immense heat, toxic gases, and potential for re-ignition hours later.
Simulating Fire Department Response
The test incorporated a critical six-minute delay after thermal runaway to simulate real-world average fire department response time. During that window, the EV fire was allowed to grow—exactly the scenario first responders face.
When UL’s fire technicians entered, they performed an initial attack without knowing the vehicle was electric. Only after initial suppression efforts revealed persistent battery ignition did they proceed to specialized tactics—like tilting the car at a 30° angle using a telehandler to access the battery underside.
This technique aligns with Tesla’s emergency response guide and some emerging U.S. fire department strategies. It aims to spray water into vent holes or damage points that open up under thermal stress.
Monitoring for Reignition and Exposure Hazards
Stopping an EV fire isn’t the same as knowing it’s safe. One of the study’s central aims was measuring how long a battery system remains a hazard. The Chevy Bolt, for example, showed active fire for up to 20 minutes, followed by hours of temperature monitoring to detect reignition. Some fires required continued observation for up to four hours.
UL monitored not just flame behavior, but environmental and occupational safety. The lab was outfitted with over 23 4K cameras and multiple thermal imagers to capture every detail. Sensors tracked water runoff for contaminants, while others monitored air quality for carcinogenic byproducts like VOCs and metal particulates.
This was especially crucial for occupational exposure analysis—evaluating risks to firefighters beyond the flames. The presence of heavy metals and unknown gases during battery burns could pose chronic health risks if not properly managed.
Post-Burn Teardown and Analysis
Once flames were out and temperatures stabilized, Munro’s dirty job began: disassembling the wreckage to examine battery damage from within. The Munro team then removed battery packs and evaluated how suppression efforts altered the structural integrity of the modules.
Three vehicles—the Tesla Model 3, Hyundai Kona, and Chevy Bolt—provided contrasting teardown insights:
- Chevy Bolt: Complete thermal runaway. Every cell failed. The pack’s aluminum housing melted, and bus bars were welded to the frame. The interior of the vehicle was totally destroyed.
- Hyundai Kona: Despite interior destruction, the battery remained mostly intact. The team found 330 volts still present, with some melted wires but no cell breach—offering insights into heat resilience in certain pouch designs.
- Tesla Model 3: Interestingly, the cabin showed minimal damage. Because Tesla’s cylindrical 18650 cells vent downward, the fire melted out the bottom tray but preserved much of the upper housing. Only one battery module remained intact—extracted with suction cups due to melted components holding others in place.
Implications for EV Design and Emergency Protocols
Several key takeaways emerged from this collaboration:
- Fire containment varies by design. The Tesla’s downward venting helped preserve the passenger cabin, while other models experienced full interior destruction.
- Thermal thresholds differ. The Kona’s pack appeared to experience 400–500°F; the Bolt and Mach-E surpassed 1100°F, enough to melt aluminum components.
- Suppression access is critical. Fires that burn long enough may expose structural weaknesses or create entry points for suppression—underscoring the need for flexible tactics like vehicle tilting.
- Delayed reignition risk is real. Even after visual extinguishment, high-voltage packs can smolder internally. Understanding this lag is vital for allocating emergency resources efficiently.
Global Collaboration and Future Research
This isn’t just a U.S. effort. UL’s panel includes representatives from Ford, GM, Tesla, and government bodies like the Department of Transportation and Idaho National Labs. Overseas observers and fire departments across North America have engaged with the study, hoping to translate findings into new response guidelines.
The project also integrates industrial hygienists from Hawaii, fire departments from Washington State, and agencies like NIOSH to assess long-term responder safety.
As EV adoption accelerates, these insights will help shape smarter firefighting practices, more resilient battery pack designs, and better occupant protection.
Conclusion: Engineering Knowledge That Saves Lives
The partnership between Munro & Associates and UL’s Fire Safety Research Institute exemplifies the value of cross-industry collaboration. Through rigorous experimentation, controlled burns, and expert teardown analysis, the team is unraveling the mysteries of EV battery fires—turning anecdotal concerns into actionable data.
As more vehicles transition to electric propulsion, this kind of EV battery fire training will be indispensable. Engineers, first responders, and policy makers alike need accurate, tested information to update fire protocols, build safer vehicles, and protect those on the front lines.
Explore more teardown insights, cost-saving innovations, and cutting-edge EV research at Munro Live.