How to check your battery health
- Open Settings and tap Battery.
- Tap Battery Health (on iPhone 14 and earlier it's called Battery Health & Charging).
- Look at Maximum Capacity: how much charge the battery holds now, compared with when it was new.
On iPhone 15 and later, you can also see the cycle count, the battery's manufacture date and its first use (on the same Battery Health screen in recent versions of iOS; earlier versions put them in Settings → General → About).
If the battery has worn down a lot, iPhone says so on the same screen and suggests a service. You don't have to wait for that message: if the phone no longer gets you through your day, that's reason enough.
What the numbers mean
Maximum Capacity is a percentage of the battery's original capacity. A battery at 85% runs out sooner than it did when new, but it still delivers power normally.
80% is the line that matters. Apple says iPhone batteries are designed to keep 80% of their original capacity at:
| Model | Rated for |
|---|---|
| iPhone 15 and later | 1,000 complete charge cycles |
| iPhone 14 and earlier | 500 complete charge cycles |
A charge cycle is using 100% of the battery's capacity in total, not one charge. Using 60% one day and 40% the next adds up to one cycle. Most people use somewhere between half a cycle and one cycle a day, so a battery that's two or three years old is often near 80%.
Peak performance and unexpected shutdowns
A worn battery can't always deliver bursts of power, for example when you open the camera on a cold morning or play a game on 20% charge. When that happens, an iPhone can shut down suddenly to protect itself. After the first unexpected shutdown, iOS turns on performance management: it smooths out power demands so the phone doesn't shut down again, which can make it feel slower.
You'll see this under Peak Performance Capability in Battery Health. A new battery removes the cause, and the phone runs at full speed again.
Signs your iPhone needs a new battery
- It drops from 30% to 0% in minutes, or shuts down with charge still showing.
- It needs charging more than once a day with the same use as before.
- It feels slower than it used to, especially opening apps or the camera.
- It gets warm doing simple things, or while charging.
- The screen is lifting from the frame, or the back is bulging. That's a swollen battery: stop charging it and read what to do about a swollen battery now.
How to make a battery last longer
Brisbane's heat is the battery's biggest enemy. Apple says iPhone works best between 0 °C and 35 °C, and that heat above 35 °C can permanently reduce battery capacity.
- Don't leave it in the car. A car parked in the sun gets far hotter than 35 °C, even in spring.
- Take it off the dashboard mount in direct sun while navigating and charging at once.
- Take off a thick case while charging if the phone gets hot. If you see Charging On Hold, the phone is too hot to charge; let it cool and it carries on by itself.
- Turn on Optimised Battery Charging (Settings → Battery → Charging, or Battery Health & Charging on older models). It learns your routine and holds the charge at 80% until you usually unplug. iPhone 15 and later can also be set to stop at 80% (or another limit) every time.
- Don't worry about small top-ups. Charging little and often is fine for lithium-ion batteries.
What happens when the battery is replaced
A battery replacement is one of the quickest repairs: the old battery comes out, a new one goes in, and the seals and screws go back. Your data stays on the phone, but it's always wise to back up first.
If a battery isn't genuine Apple, or wasn't fitted by Apple's own network, iPhone XR, XS and later models show a message that the battery couldn't be verified, and Settings → General → About → Parts and Service History lists it. It doesn't stop the battery working. Here's what that message means.
Sources
- Apple Support: About the battery and performance of iPhone 11 and later
- Apple Support: About iPhone Parts and Service History
- Apple Support: If your iPhone or iPad gets too hot or too cold
- Apple: Maximising battery life and lifespan
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