Guide
Swollen or bulging battery: what to do right now
A battery case that bulges, cracks or no longer fits its slot is a warning, not a cosmetic problem. Stop, keep calm and follow the steps below.
Quick answer
A swollen EV battery has damaged cells that are making gas. Stop riding and charging at once, move it to an open, dry place away from people and anything that burns, and do not press, puncture or open it. Then call a battery service centre.
Why a battery swells
Inside a lithium cell, chemical breakdown can produce gas. The gas has nowhere to go, so the cell puffs up and pushes on the pack case. A swollen cell is a damaged cell, and it is more likely to leak or catch fire.
- Ageing: old cells wear out and slowly build up gas.
- Overcharging: a wrong or faulty charger, or a failed BMS, pushes the cells too far.
- Heat: parking and charging in strong sun speeds up the chemical breakdown.
- Damage: a fall, a pothole hit, water entry or a manufacturing flaw in one cell.
Danger signs to look for
- The case bulges, cracks or the lid no longer closes properly.
- The battery is hard to slide in or out of its slot.
- It gets very hot while charging or riding, or smells sweet, chemical or burnt.
- Hissing, popping, leaking liquid or smoke. Treat smoke as a fire: get everyone out and call 112.
Exactly what to do
- Stop riding and stop charging at once. Unplug the charger at the wall if it is safe to reach.
- If it is removable and not hot or smoking, carry it gently to an open, dry place outdoors, away from people, children, vehicles, gas cylinders, fuel and anything that burns.
- If it is fixed in the scooter, leave the scooter outside in the open, not in the house, lift or basement.
- Do not press, puncture, cut or drop it, and never try to let the gas out.
- Do not open the pack yourself or let a roadside mechanic open it.
- Call our service line on 99091 21102. We will tell you how to bring it in safely.
How to stop it happening
Use only the original or a matching approved charger, park in shade, let a hot battery cool before charging, and get a pack checked after a hard fall or deep water. Our EV battery care guide covers daily charging habits in more detail.
Questions
Frequently asked questions
Is a swollen EV battery dangerous?
Yes. Swelling means the cells are damaged and producing gas, which raises the risk of leaking or fire. Stop using and charging it straight away.
Can I still ride with a slightly swollen battery?
No. Even slight swelling will not go back to normal, and riding adds heat and vibration. Have it checked before using it again.
Can a swollen battery be repaired?
Swollen cells themselves must not be reused. Whether the rest of the pack can be saved depends on the test result; we will tell you before any work.
Should I put a swollen battery in water?
No. Just move it to an open, dry place away from people and things that burn, and call us. If it smokes or flames, leave it, get people away and call 112.
Battery bulging? Call service first
Call 99091 21102 before you move or transport a swollen pack. Diagnosis is free, for any brand.