What Fire Extinguisher Works on a Lithium-Ion Battery Fire?

What's going on inside a pack

A lithium-ion battery is a bunch of cells packed together. Inside each cell, a thin separator keeps the positive and negative sides apart.

When a cell gets crushed, punctured, overcharged, or overheated, that separator can fail. Sometimes it's just a bad cell from the factory. Either way, the cell shorts inside itself and heats up fast.

That heat breaks down the electrolyte, the liquid inside the cell. It turns into hot gas that's flammable and toxic. The cell swells, vents, and can catch fire. The heat spreads to the cell next to it, and that one goes too. That chain is thermal runaway.

Here's the part that matters for you. The reaction makes its own heat. Covering it or smothering it doesn't stop what's happening inside the cells. A pack can look out and flare back up minutes or hours later.

Why the ABC on your wall won't cut it

An ABC extinguisher throws dry chemical powder. It's good at knocking flames down. On a battery, it can knock down the flame and may suppress the fire, but it probably won't put it out, because it doesn't cool the cells inside.

The powder coats the case, and the cells under it keep heating. So you get a pack that looks out, then lights back up. There aren't any peer-reviewed studies yet on what suppresses a lithium battery fire, so we don't claim a rating for any extinguisher on one.

Keep your ABC. It's still what you want for the cardboard, the bench, and the wall behind the charger. Just don't count on it for the battery itself.

Why cooling matters most

Fire departments put a lot of water on battery fires, and cooling is the reason. Water pulls heat out of the cells and slows the spread from one cell to the next.

F-500 extinguishers are water-based. The agent is mixed into the water to help it soak in and pull heat out faster. That's why it's the best bet to fight a battery fire, and why it goes by the chargers instead of another powder unit.

Don't count on any handheld to stop a burning pack, big or small. A scooter, an e-bike, or a forklift battery holds a lot of energy, and any pack that catches is a 911 call.

We stock and sell F-500 extinguishers, and we inspect and service them.

When a pack starts smoking

• Get people away from it. The smoke is toxic. Don't stand in it.
• Call 911, even if you think you've got it handled, because it can come back.
• If it's small, and you can move it outside without getting into the smoke, use a shovel or tongs. Set it on concrete or dirt, away from the building. If you can't do that safely, leave it and get out.
• If you put water on it, do it from as far back as you can, and only to cool it while the fire department is on the way.
• Keep an eye on it for at least 24 hours. A pack that looks dead can relight.

Where the batteries are in your building

Tool battery chargers. Shops charge packs on a bench, a lot of times right next to rags, cardboard, and solvent. Give the chargers their own spot on a metal shelf or bench, clear of anything that burns.

E-bikes and scooters. People bring them into break rooms, hallways, and apartments and plug them in by the door. That's usually the exit, so if a pack goes, the fire ends up between people and the way out. Charge them away from exits.

Forklifts and fleet equipment. Lithium forklift packs and electric fleet vehicles hold a lot of energy in one place. Charge them in one area, keep that area clear, and make sure everybody knows who calls 911.

Mining equipment. A lot of mines and fleets run diesel and electric machines side by side. On a diesel machine, the ABC is still the right extinguisher for a lot of what can burn on the iron, like fuel, hydraulic fluid, and ordinary combustibles. A battery pack on an electric machine is a different problem. We haven't seen any studies or completed tests yet that show which extinguisher or agent puts out a lithium-ion battery fire, so we won't tell you one does. Keep the ABC on the machine for the fires it can fight. If a pack catches, get the operator off the machine and get everybody away from it.

For all of them: use the charger that came with the battery. Pull swollen, cracked, or damaged packs out of service. Don't leave a pile of packs charging overnight with nobody around. And pick one spot outside where a bad pack can go.

What to hang near the chargers

Here's what we'd tell you on a walk-through:

• ABC extinguishers for the room, same as always, for the cardboard, the bench, and anything else around the chargers that can burn.
• A clear path out, with nothing parked in it.
• An F-500 unit near the charging area, on the way out, not right on top of the charger. You don't want to be reaching over a smoking pack to grab it.
• If it's a whole room full of chargers, or equipment that sits unattended, what matters most is where it charges, what's around it, and how people get out. We'll walk it with you.

Whatever you hang needs to be looked at every month and inspected and serviced like any other extinguisher. We keep the due dates. You don't have to think about them.

For how lithium fits against the letter classes, see classes of fires.

Tell us where the batteries are

Call 1-800-348-9604. Tell us where the batteries are and how they get charged. We'll walk it and tell you what to hang. We sell, hang, inspect, and service extinguishers, including F-500.