How do I know if my phone battery needs replacing?

The common signs are: it no longer lasts the day on the same usage, the percentage jumps or the phone shuts down well above 0%, it cuts out in the cold or under load, it heats up on a slow charge, the back panel bulges, or the phone's own battery-health reading is low.

How long does a phone battery last?

Phone batteries are consumables and wear out by design, typically after two to three years or roughly 500 full charge cycles.

What battery health percentage means it is time to replace?

Below roughly 80% capacity is the point at which the manufacturer itself suggests replacement. iPhones show this in Settings then Battery; many Android brands have a diagnostics code or app.

6 signs your phone battery needs replacing

30 July 2026 · PhoneTech

Phone batteries are consumables — they wear out by design, typically after 2–3 years or roughly 500 full charge cycles. The good news: a worn battery is one of the cheapest fixes that makes an old phone feel new again. Here’s how to tell it’s time.

1. It dies before the day does

A battery that used to last a full day but now needs an afternoon top-up on the same usage has lost real capacity.

2. The percentage jumps

Dropping from 40% to 15% in minutes, or shutting down at 20%, means the battery can no longer report or hold charge reliably.

3. It shuts off in the cold or under load

Sudden shutdowns while using the camera, GPS, or games are a classic worn-cell symptom.

4. The phone heats up while charging normally

Warmth during fast charging is normal; a phone that gets hot on a slow overnight charge is not.

5. The back panel is bulging

A swollen battery physically pushes the screen or back panel outward. Stop using the phone and replace the battery — this one is a safety issue, not just a convenience issue.

6. Battery health says so

iPhones show it in Settings → Battery; many Android brands have a diagnostics code or app. Below ~80% capacity, replacement is what the manufacturer itself suggests.

Replacing it

A replacement battery for most phones costs far less than people expect — often less than a month of mobile data. Look up your model to see the exact battery for your phone; fitting at a local repair shop is usually quick, and for a swollen battery, let the shop handle removal.

Common questions

How do I know if my phone battery needs replacing?: The common signs are: it no longer lasts the day on the same usage, the percentage jumps or the phone shuts down well above 0%, it cuts out in the cold or under load, it heats up on a slow charge, the back panel bulges, or the phone's own battery-health reading is low.
How long does a phone battery last?: Phone batteries are consumables and wear out by design, typically after two to three years or roughly 500 full charge cycles.
Is a bulging back panel dangerous?: Treat it as a safety issue rather than a convenience one. A swollen battery physically pushes the screen or back panel outward. Stop using the phone and have the battery replaced, and let a shop handle removal.
What battery health percentage means it is time to replace?: Below roughly 80% capacity is the point at which the manufacturer itself suggests replacement. iPhones show this in Settings then Battery; many Android brands have a diagnostics code or app.