Lithium Battery Fires

Lithium-ion batteries power tools, e-bikes, scooters, phones, vehicles and storage systems. When damaged, overheated or defective, they can enter thermal runaway: a self-heating chain reaction that causes fire, explosion and toxic smoke. These fires are hard to put out and can reignite.

• Workers
• Homeowners
• Fleet & Warehouse

What causes them

• Physical damage: dropped, crushed or punctured cells
• Overcharging, wrong chargers or cheap uncertified batteries
• Heat: left in hot vehicles, near heaters or in direct sun
• Short circuits from loose metal touching terminals
• Manufacturing defects
• Age and wear

Warning signs

• Swelling, bulging or deformed case
• Unusual heat while charging or sitting idle
• Hissing, popping or crackling sounds
• Leaking fluid or a sweet, chemical smell
• Smoke or discoloration
• Rapid loss of charge or poor performance

If you see these signs, stop using the battery, and move it away from combustibles if you can do so safely.

Prevention

• Buy certified products from reputable sources (UL or similar listings). Use the manufacturer's charger. See Cordless Tool Battery Handling.
• Charge in a clear, non-flammable area, with smoke alarms. Don't charge on beds, couches or in exits. See E-Bike Battery Fires.
• Do not leave charging unattended or overnight where possible.
• Store at moderate temperatures, away from heat and flammables; use fire-resistant containers or cabinets for large amounts.
• Recycle old batteries. Never throw them in trash.
• For workplaces, follow fire code limits on quantity and use charging rooms with detection and fire protection. See Battery Charging Rooms.

If a battery overheats or burns

1. Get everyone out and away from smoke, which is toxic. Close the door behind you.
2. Call 911 and tell them it is a lithium-ion battery fire.
3. For a very small fire in a device, if you are trained and it is safe, a large amount of water or a suitable extinguisher can cool it. For larger packs, vehicles and storage systems, leave it to the fire department.
4. Expect reignition. Damaged batteries should be isolated outdoors and watched for hours or days.

Last updated: October 8, 2026