From phones and laptops to e‑bikes and electric vehicles, lithium batteries are everywhere in modern life. When they fail, they can go into “thermal runaway” and turn into an intense, fast‑spreading fire that behaves very differently from a trash can or cooking fire.
This guide walks you through what to look for, what to do, and what not to do when a lithium battery starts to fail.
First: Understand The Risk
Lithium‑ion and lithium‑metal batteries store a lot of energy in a small package, and when they fail they can release that energy in seconds.
Key dangers include:
- Extremely high heat and jet‑like flame vents from the cell.
- Toxic, irritating smoke and gases.
- Exploding shrapnel at velocities comparable to a 9mm gun
- Cell‑to‑cell propagation: one burning cell can ignite the next.
- Re‑ignition after the visible flames are out if the pack is still hot.
Because of this, even professionals often focus on cooling and containment as much as “extinguishing.”
Early Warning Signs To Act On
Most serious incidents start with warning signs minutes or even hours before open flame.
Watch for:
- Device or battery pack too hot to touch under normal use.
- Swelling or bulging case on a phone, laptop, power bank, e‑bike pack, etc.
- Hissing, popping, or crackling sounds from the battery area.
- Chemical or “sweet and metallic” burning smell, smoke, or discoloration.
If you see any of these:
- Unplug the device, turn it off if you can do so safely.
- Move it away from combustibles (paper, fabric, curtains, fuel).
- If possible, move it outdoors to a non‑flammable surface and stay away from it.
- Do not puncture, stomp on, or squeeze a swollen pack.
What To Do When A Lithium‑Ion Battery Catches Fire
Once there is flame, your priorities are: protect people, call help, then cool and contain.
1. Get People Safe And Call 911
- Evacuate everyone from the room or vehicle area if the fire is more than “tiny trash‑can” size.
- Close doors behind you to slow fire spread if you’re leaving a room.
- Call emergency services and tell them it’s a lithium battery fire (phone, scooter, EV, storage system, etc.).
2. For Small Lithium‑Ion Fires: Use Water
For consumer lithium‑ion batteries (phones, laptops, tools, e‑bikes), there is very little reactive lithium metal, so water is acceptable and widely used by aviation and fire authorities
For a small device you can safely approach:
- A large volume of water can knock down the flames and start cooling the pack; some guidance even suggests water or non‑sugary drinks in aircraft cabins when nothing else is available.
Specialized Containment Products:
- UL5800 approved lithium battery fire containment products guarantee 6 hours or containment. We recommend Lithium Fire Guard’s PG100 which can be deployed in seconds, protects the user, complete gas and smoke containment and post containment stabilization allowing for safe transport and preventing future reignition.
If you cannot safely control it in seconds, leave and close the door. Let firefighters handle it.
After The Flames Are Out: Prevent Re‑Ignition
Extinguishing the visible fire is only half the job; packs in thermal runaway stay hot internally and can flare up again.
Best practices include:
- Keep cooling: Continue applying water over the pack for an extended period if you can do so safely to pull heat out of the remaining cells.
- Move it to a safe area: If responders advise it and it’s safe, the pack may be transferred to a fire‑resistant container or moved outdoors on concrete or bare ground.
- Maintain distance: Treat it as live; don’t pick it up with bare hands even if it “looks dead.” Temperatures can still be high enough to cause burns or reignition.
- Ventilate: Open windows and doors once safe to reduce smoke and gas concentrations.ifixit+1
Professionals sometimes submerge a small device in water for many hours (24 hours or more) to ensure all cells are cooled before disposal.
What You Should Never Do
Some instinctive reactions make lithium battery incidents worse.
Avoid:
- Throwing a burning pack in the household trash or a regular dumpster.
- Covering a hot or burning pack with blankets or insulation (this traps heat and can accelerate thermal runaway)
- Using a Class D metal extinguisher on lithium‑ion fires (these are meant for metallic lithium; guidance warns against using them on “regular” Li‑ion device fires).
- Bringing the pack into your car to “deal with it later.”
- Trying to disassemble, puncture, or crush a damaged battery.
If in doubt, back away, close the door, and wait for the fire department.
Preparing Ahead: How To Reduce Your Risk
The best way to “put out” a lithium fire is to prevent it from starting.
Practical prevention tip:
- Buy certified batteries and chargers from reputable manufacturers.
- Avoid cheap, unlisted replacement packs and “fast chargers.”
- Don’t charge devices under pillows, on beds, or on flammable surfaces.
- Don’t leave e‑bikes, scooters, or large packs charging overnight or unattended.
- Store large batteries away from exit paths and combustibles.
- Replace batteries that swell, overheat, or show physical damage.
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