Lessons from New York: What NFPA testing revealed about EV fire blankets

At the leafy Rockland County Fire Training Ground, just north of New York, USA, a landmark series of electric vehicle (EV) battery fire tests were conducted in May 2025, bringing together experts from across the world to better understand how lithium-ion battery fires behave and how best to manage them safely.

EV FireSafe’s Emma Sutcliffe and Dan Fish were there — and what they captured on video reinforces why they're against the promotion or use of EV fire blankets for untrained personnel.

The testing was conducted by the National Fire Protection Association (NFPA USA), the Energy Security Agency (ESA) and the Fire Risk Alliance (FRA) among other expert organisations and experts.

Globally important testing

The testing was part of a global research program exploring EV firefighting tactics, tools, and the risks associated with stranded energy - the electrical charge remaining in a damaged and/or burnt EV battery pack that can lead to delayed or secondary ignition days, weeks or months later.

The aim was to test different firefighting approaches and equipment in controlled conditions, generating real-world data to guide fire service tactics, policy, and safety standards for EV incidents.

Violent deflagration of trapped gases

Among the many tests conducted, one stood out; the use of a heavily marketed brand of EV fire blanket.

Commonly believed to be a tool to 'extinguish' EV battery fires, the blanket was deployed over an EV with a battery in active thermal runaway, initiated by overcharge. To simulate a real-world incident, thermal runaway was left to build for some minutes prior to an initial knock down with water, then the EV (which had a very large 110kWh battery capacity) was covered with the non-porous blanket for approximately 60 minutes.

As expected, the use of the EV fire blanket smothered visible flames originating from the combustion of flammable interior materials, but did not extinguish thermal runaway, which continued under the blanket.

This was confirmed by the appearance of gases, particularly at the rear of the EV, from underneath the blanket, and by flames that were visible from the battery pack when firefighters lifted the blanket momentarily to slide a spray system underneath the EV.

After 60 minutes, and as the ESA crew - consisting of at least 7 firefighters on the ground, two on hoses and multiple more controlling the test from behind a safety line - prepared to remove the blanket, a corner was lifted, allowing air into the space.

This adjustment was necessary as the bonnet of the EV had burnt away, and both firewater and rain had accumulated on the blanket, preventing easy removal.

A few seconds later, as the crew attempted to lift the blanket off the EV, and oxygen was reintroduced, the trapped gases ignited in a violent deflagration — a rapid, explosive ignition of gases that was significant enough to knock seven firefighters off their feet.

The EV fire blanket deflagration was an incredibly confronting display of the power and unpredictability of lithium-ion battery pack off-gassing, particularly as the ESA team are highly experienced firefighters.

Emma Sutcliffe, EV FireSafe Director and testing technical panel member

Why did the explosion occur?

While these products are often marketed as an easy way to contain flames or smoke, they can instead trap dangerous and highly flammable off-gases, including hydrogen, carbon monoxide, and volatile hydrocarbons.

Testing and research by our colleague Emeritus Professor Paul Christensen found approximately half of all off-gases were hydrogens which, as all firefighters and HAZMAT technicians are aware, should not be allowed to build up to explosive levels.

When these gases accumulate and oxygen is reintroduced — even from lifting a small section of the blanket, or from a wind gust — the result can be a sudden and violent explosion.

What does the explosion mean for real-world EV safety?

For EV FireSafe, this event confirmed what years of research have already shown: EV fire blankets are not a simple or inherently safe solution to EV battery fires.

It's for this reason EV FireSafe does not promote or sell EV fire blankets, and we strongly oppose their use by untrained or unqualified personnel, particularly in automotive workshops, fleet depots, and public charging facilities.

Unless used under strict, controlled, and well-trained conditions — typically by fire services with full personal protective clothing and equipment and incident command — fire blankets may pose more risk than reward.

Thermal imaging results

During testing, EV FireSafe were able to film the explosion using a FLIR thermal imaging camera (TIC), which can be seen in the complete video.

The maximum temperature reached during the deflagration was approximately 385 degrees Celcius, however as it occurred so rapidly, this is not anticipated to be a fully accurate measurement, however the vision provides potential thermal impact.

As can be seen in the video, there are no visible flames at the time of maximum recorded temperature, due to the rapid and clean burn up of primarily hydrogen gases.

Images: Left TIC image shows temperature of 44.4°c on the outside of EV fire blanket; on right shows maximum recorded temperature of 358°c as the deflagration occurs. Source: EV FireSafe.

Data driven learning

The purpose of the NFPA ESA testing program wasn’t to create alarm, but to generate data-driven guidance for how the global emergency response community can adapt to a world of electrified transport safely.

By testing, observing, and documenting these events, organisations like the NFPA and EV FireSafe are helping shape the standards that will protect both responders and the public.

As EV FireSafe's Head of Technical, Dan Fish, noted after the event:

“Every test, even the explosive ones, teaches us something valuable. We can’t fear these technologies — but we must remain alert, not alarmed, and ensure we respect them.”

Key EV fire blanket takeaways for responders

Electric vehicle battery fires are complex, high-energy events that demand specialist knowledge and training. There are no shortcuts to safety — and certainly no single tool that can replace understanding, preparation, and collaboration.

Through our partnership with global research programs like the NFPA, EV FireSafe remains committed to evidence-based safety education, helping organisations and responders work confidently and safely in a rapidly electrifying world.

More information about the testing program can be found here - Assessment of EV Firefighting Techniques and the Impact on Stranded Energy

The NFPA ESA webinar can be viewed here - Assessment of EV Firefighting Tactics and Tools - The Impact on Stranded Energy; Experimental Findings

Moving into 2026, EV FireSafe is focused on the development and delivery of real-world, high quality online and in-person training, not just for emergency responders, but also for business and industry, particularly in critical infrastructure environments.

For more information on our training programs, please head to evfiresafe.training or email hello@evfiresafe.com