The Challenges Of Putting Out Electric Vehicle (EV) Fires

With the government encouraging us to get electric vehicles (EV), we all need to be aware of possible electric vehicle fires. Currently, if an EV fire occurs, the most common solution to effectively put out an EV fire is to use lots of water to cool down the battery material. These fires burn at much higher temperatures and require a lot more water to fight than conventional car fires. One of these fires can get as hot as nearly 5,000 degrees Fahrenheit.

When we say “lots of water“, there have been reports from fire departments that it’s not uncommon for an EV fire to take between 6,600 - 13,200 gallons of water to extinguish. To put that into perspective, a petrol or diesel car fire tends to only take between 525 - 1,050 gallons to extinguish. And, the dangers posed by EV fires do not end with putting out the flames, as there have been cases of EV fires reigniting sometimes even days after being extinguished!

An EV battery pack is made up of thousands of smaller lithium-ion cells. A single cell might look like a pouch or cylinder, and is filled with the chemical components that enable the battery to store energy: an anode, a cathode, and a liquid electrolyte. The cells are assembled into a battery pack that’s encased in extremely strong material, like titanium, and that battery pack is normally bolted to the vehicle’s undercarriage. The idea is to make the battery almost impossible to access and, ideally, to protect it during even the nastiest of collisions.

When an EV battery is defective, damaged, or just internally fails, one or more lithium-ion cells can short-circuit, heating up the battery. At that point, the tiny membranes that separate the cathode and the anode melt, exposing the highly flammable liquid electrolyte. Once a fire ignites, heat can spread to even more cells, triggering a phenomenon called ‘thermal runaway’. When this happens, flames continue igniting throughout the battery, fueling a fire that can last for hours.

As thermal runaway takes hold, bright orange flames can quickly engulf an entire car. And because EV batteries are packed with an incredible amount of stored energy, even when the fire appears to be over, latent heat may still be spreading within the cells of the battery. One firefighter compared the challenge to a trick birthday candle that reignites after blowing it out. Because EV fires are different, EV firefighting presents new problems. Firefighters often try to suppress car fires by, essentially, suffocating them. They might use foam extinguishers filled with substances like carbon dioxide that can draw away oxygen, or use a fire blanket that’s designed to smother flames. But because EV fires aren’t fueled by oxygen from the air, this approach generally doesn’t work.

Michael O’Brian, a firefighter in Michigan who serves on the stored-energy committee for the International Association of Fire Chiefs, suggested that sometimes the best strategy is to protect surrounding property and let the vehicle burn. As with all car fires, he says his priority isn’t to salvage the vehicle but rather to protect other endangered property.

Although EV’s are relatively rare in our area right now, electric car fires do present a new technical and safety challenge for fire departments on the best firefighting strategies to use on them. There is a pressing need to develop a more effective measure to combat EV fires and that cannot be overstated!

Clay County Fire & Rescue Week of July 12 – July 19, 2023 Total calls = 24 Medical Assist Calls – 15 Dispatched, Cancelled En Route – 3 Motor Vehicle Accident – 1 Assist Police – 1 Vehicle Fire – 1 Carbon Monoxide Check – 1 Downed Power Line – 1 False Alarm - 1

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