iPhone Battery Health: When Should You Replace the Battery?

If your iPhone needs charging by lunchtime, switches off in the cold or feels slower than it used to, the battery is the first thing to check. Every lithium-ion battery wears out with use. The good news is that a worn battery is one of the simplest and most cost-effective phone repairs.

How to check your iPhone battery health

Open Settings → Battery → Battery Health & Charging (on some iOS versions it is Battery Health). You will see two useful pieces of information:

• Maximum Capacity: how much charge the battery can hold compared with when it was new.
• Peak Performance Capability: whether the battery can still deliver enough power, or whether iOS has started to manage performance to prevent unexpected shutdowns.

If you see a message saying the battery has degraded significantly, or a “Service” recommendation, the battery is due for replacement.

What percentage is “too low”?

Apple explains that iPhone batteries are designed to keep a high proportion of their original capacity for a set number of full charge cycles, and that ageing batteries can lead iOS to manage performance. You can read Apple’s own explanation on its iPhone battery and performance page and its general batteries guide.

In practice, once Maximum Capacity drops to around 80% or below, most people notice shorter battery life and a replacement makes a clear difference.

Signs your iPhone battery needs replacing

• Battery life no longer gets you through a normal day
• Your iPhone shuts down suddenly, even with charge left
• The percentage jumps around (for example from 30% to 5%)
• The phone gets warm during light use or charging
• Apps feel slower than they used to
• The screen is lifting or the case is bulging, which can mean a swollen battery. Stop using and charging the phone and get it checked straight away.

Battery replacement or a new phone?

If your iPhone is otherwise in good condition, a new battery can make it feel close to new again for a fraction of the cost of upgrading. It also keeps a working device in use for longer, which is better for the environment. If the screen, charging port or other parts are also failing, it is worth comparing the total repair against an upgrade. See our guide to repairing or replacing your phone.

Tips to make a new battery last longer

• Turn on Optimised Battery Charging in battery settings
• Avoid leaving your phone in very hot places, such as a car dashboard in summer
• Use a good-quality cable and charger
• Keep iOS up to date

For more ideas, read our tips to make your phone battery last longer.

How long does an iPhone battery replacement take?

Most iPhone battery replacements are done the same day, often while you wait. See prices and book on our iPhone battery repair page.