A screen that's lifting away slightly, a back that's bulging, a remote control or a phone that seems thicker than before… These are the classic signs of a swelling battery. It happens more often than people think, and it deserves to be taken seriously.
Don't panic, though: in the vast majority of cases, if you act quickly, there's no real danger.
Why a battery swells
Lithium-ion and lithium-polymer batteries (the two types used in our smartphones) contain an electrolyte. Over time, through charge/discharge cycles, excessive heat, or repeated knocks, that electrolyte breaks down and produces gases.
These gases build up and inflate the battery pouch, hence the visible swelling.
The most common causes:
- Age: a battery has a limited lifespan (300 to 500 full cycles). Beyond that, degradation accelerates
- Excessive heat: leaving your phone in the sun, in a car in summer, or gaming while charging
- Repeated overnight charges: forcing the battery to stay at 100% for hours wears the cells faster
- Knocks or crushing: a physically damaged battery can swell even if it's recent
The signs to recognise
Obvious visual signs
- The screen lifts slightly on one or several sides
- The back of the phone (plastic or glass) is bulging, no longer sits flat
- A visible gap has appeared between the screen and the chassis
- The protective case no longer fits properly
Less obvious signs
- The phone runs hotter than before, even without heavy use
- Battery life has collapsed suddenly (less than half the usual runtime)
- The phone restarts on its own or shuts down at 20–30% battery
If you spot any of the visual signs (screen lifted, bulging back), stop charging the phone immediately. Don't try to puncture or crush the battery. Bring it to a technician as soon as possible.
The real risks
A swollen battery isn't necessarily about to explode, but it's not something to ignore either.
Low risk if:
- The swelling is recent and modest
- The phone isn't running abnormally hot
- You've stopped charging it
Higher risk if:
- The battery is heavily bulging and significantly deforms the device
- You notice a chemical or acrid smell
- The phone runs hot even when switched off
- The battery has been punctured or crushed
In these last cases, lay the phone flat on a non-flammable surface, don't keep it in your pocket, and have it looked at promptly.
What to do urgently when you spot a swollen battery
- 1Stop charging the phone immediately, unplug the cable and don't plug it back in. Each additional charge cycle increases the internal pressure and the risk.
- 2Switch the device off if possible, a phone that's off draws less power, which reduces the strain on the damaged battery. If the screen is significantly lifted, handle it carefully to avoid pressing on the battery.
- 3Place it on a flat, non-flammable surface, not in your pocket, not on a bed or a sofa, not on a wooden surface. A ceramic or metal surface is ideal, away from documents and flammable materials.
- 4Don't open the device yourself, the temptation to remove the battery yourself is understandable, but a swollen battery is under pressure. Clumsy pressure can cause a tear, a gas leak, or an electrical arc. Leave this work to a properly equipped technician.
- 5Take it quickly to the workshop or to an approved collection point, within 24 to 48 hours. A battery replacement takes less than an hour. If the battery is heavily bulging or there's a chemical smell, don't delay.
What not to do
- ❌ Don't puncture the battery to "deflate it"
- ❌ Don't throw it in the bin as it is (it's hazardous waste)
- ❌ Don't keep charging it hoping it will sort itself out
- ❌ Don't try to remove it yourself without experience: a swollen battery is fragile, clumsy pressure can cause an electrical arc
The solution: replacement
A battery replacement definitively solves the problem. It's a routine job at the workshop: on most smartphones, it takes less than an hour.
The cost depends on the model and the part chosen, see the workshop pricing for an estimate.
If your phone is more than 3 years old with a worn battery, take the opportunity to ask for a full diagnostic. Sometimes it's the right moment to weigh up whether the repair is worth it or whether a replacement makes more sense.
Preventing swelling
A few simple habits to look after your battery:
- Charge between 20% and 80% as often as possible, avoid repeated 0% to 100% charges
- Avoid heat: no phone in a sunlit car, no charging under a pillow
- Use the original cable or a certified, quality charger
- Remove the case while charging if the phone is running hot
These habits can easily double the lifespan of your battery.
Swollen battery or poor battery life? Bring your phone to the workshop, I'll diagnose it free of charge.
Frequently asked questions
Can a swollen battery explode?+
How much does it cost to replace a swollen iPhone battery?+
Can you keep using a phone with a swollen battery?+
How do you tell if your battery is swelling?+
How long does a smartphone battery last?+
In short
A swollen battery shows itself through a lifted screen, a bulging back, or unusual heat. It's caused by the normal degradation of lithium cells, accelerated by heat and excessive charge cycles.
The right reaction: stop charging, avoid heat, and have the battery replaced quickly by a technician. It's a simple, low-cost repair that gives the device a second life.
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