Battery pack is dropped, dented, swollen or wet

The battery was dropped (for example while swapping), hit in a crash, is dented or cracked, looks swollen or bulging, or got water inside. Removable packs are tested for a drop under UN Regulation 136, but that does not mean every drop is safe: a hard knock can damage cells inside without any outside sign. Damage can lead to a cell heating by itself (thermal runaway), toxic gas and a fast-spreading fire, sometimes hours or days later. London Fire Brigade lists swelling, lumps, leaking and damage to the case as warning signs. A damaged lithium-ion battery cannot be safely repaired (Consumers' Federation of Australia).

Is it safe to ride?

Stop now. Immediate rule: stop, isolate, keep away, report. Do not ride, charge or fit a damaged battery.

Quick checks first

• Smoke, hissing, crackling, heat or a chemical smell? Move away at once and call the fire service.
• Is the case swollen, cracked, dented or leaking?
• Was it dropped from a height, hit in a crash, or under water?

Diagnose it step by step

1Is there smoke, hissing, crackling, heat or a chemical smell?

• Yes: get away, keep others away, call the fire service. Do not try to put it out (London Fire Brigade). Stop here.
• No: go to step 2.

2Is the case swollen, bulging, cracked, dented, punctured or leaking?

• Yes: the battery is damaged. Follow Handle a damaged battery pack: place it outdoors on bare ground or concrete away from anything that burns, keep people away, report to the operator or dealer.
• No: go to step 3.

3Was it dropped hard, hit in a crash, or submerged?

• Yes: treat it as damaged even if it looks fine. Do not fit or charge it. Report it with its ID and what happened. Gogoro, for example, tells riders not to drop or strike its batteries; the operator decides if a battery can return to service. For water, see Bike has been in deep water or a flood.
• No (a light knock, no marks): go to step 4.

4. After a light knock, fit it only if the operator or manual allows, and watch closely. Does it show any warning, unusual heat, or smell in the next charge or ride?

• Yes: stop at once. Go back to step 1.
• No: report the knock to the operator anyway, so they can check the battery's data.

5. Has the bike had a crash? Check the rest of the bike too: The bike has been dropped or crashed. A fixed battery in a crashed frame needs a workshop check before charging: Make an electric motorcycle safe to work on.

What happens if you charge or ride a damaged pack: charging adds energy to a damaged cell and can start thermal runaway. Fires from these batteries spread fast and give off toxic smoke (London Fire Brigade).

Causes, most likely first