7 Signs Your iPhone Battery Needs Replacing

1. Maximum capacity has dropped below about 80%

Go to Settings → Battery → Battery Health (called Battery Health & Charging on some iOS versions). Maximum Capacity compares your battery with when it was new. Apple designs iPhone 14 and earlier batteries to keep about 80% of their capacity after 500 full charge cycles, and iPhone 15 models after 1,000 cycles, under ideal conditions. Once you're under 80%, shorter battery life is normal.

2. Your iPhone shows a "Service" message

If Battery Health says the battery has significantly degraded and recommends service, Apple's own guidance is that a replacement will restore full performance and capacity. The message doesn't mean the phone is unsafe to use, but you'll likely notice more problems.

3. It shuts down unexpectedly

A worn battery can't always deliver the power the phone asks for, especially in the cold or at 20–30% charge. If your iPhone switches off and then shows plenty of charge when you plug it in, the battery is the usual cause.

4. It doesn't last the day anymore

If you're charging at lunch when you never used to, and your usage hasn't changed, the battery has lost capacity.

5. The phone feels slower

When a battery degrades, iOS can manage performance to prevent sudden shutdowns. Battery Health tells you whether this "peak performance capability" management has been applied. A new battery removes the need for it.

6. It gets hot during normal use

Some warmth while charging or gaming is normal. A phone that gets hot while doing simple tasks, or while charging overnight, should be checked.

7. The screen or back is bulging

A swollen battery is the one sign you shouldn't ignore. If the screen is lifting or the back is pushed out, stop charging the phone, keep it somewhere cool, don't press on it, and get it replaced as soon as possible.

How to make your next battery last longer

• Avoid leaving the phone in a hot car or in direct sun.
• Use the charging optimization options in Battery settings.
• Use a good-quality cable and charger.
• On iPhone 15 and later, you can see the cycle count under Settings → General → About.

Source: Apple Support: iPhone battery and performance.