The battery is the first thing you notice when an iPhone starts getting older: by mid-afternoon you’re already hunting for an outlet. The good news is that the iPhone itself tells you what shape its battery is in, and iOS 27 has several settings to stretch it. Here’s where to look, how to read it, and what you can do.
Where to check battery health
Go to Settings > Battery and open the battery health section. You’ll see two important pieces of information there:
- Maximum Capacity: how much charge the battery can hold compared with when it was new. If it says 85%, a full charge gives you 85% of the battery life you had on day one. It’s normal for a brand-new iPhone to show slightly less than 100% if some time passed between when it was made and when it was activated.
- Peak Performance Capability: tells you whether the battery can still deliver all the power the iPhone needs. If you see a message saying the battery health has significantly degraded, it’s time to replace it.
On iPhone 15 or later, you can also see the cycle count in Settings > General > About. A cycle is using the equivalent of 100% of the battery, even across several charges: using 50% today and another 50% tomorrow counts as one cycle.
What percentage is “normal”?
According to Apple, under ideal conditions:
- iPhone 14 and earlier: retain 80% of their original capacity after 500 complete cycles.
- iPhone 15 and later: retain 80% after 1,000 complete cycles.
In other words, if you have an iPhone 15 or newer, its battery is designed to last quite a bit longer. Below 80% is when most people start to notice they don’t make it to the end of the day.
The charge limit: the setting that protects it most
Lithium-ion batteries suffer more when they spend a lot of time at 100%. That’s why, on iPhone 15 and later, you can set a charge limit in Settings > Battery > Charging: 80, 85, 90, or 95%, or leave it at 100%. If you charge overnight and don’t usually use up the whole battery in a day, an 80 or 85% limit is a good way to extend its life. On earlier models you have Optimized Battery Charging, which learns your routine and waits to charge past 80% until shortly before you unplug.
iOS 27 settings to make it last all day
- Adaptive Power (Settings > Battery > Power Mode): on iPhones that support Apple Intelligence, it adjusts performance when it predicts you’ll use more than usual. It’s on by default on iPhone 17 and iPhone Air; on other models, turn it on yourself.
- Automate Low Power Mode: in iOS 27, you just describe what you want in Shortcuts, as I explained in the iOS 27 tricks.
- Always-On display: if your iPhone has it, turn it off or remove the wallpaper and notifications in Settings > Display & Brightness.
- Limit Frame Rate (Settings > Accessibility > Motion): drops the display from 120Hz to 60Hz. It feels less smooth, but it saves power.
- Location: check which apps use it “Always” in Settings > Privacy & Security > Location Services and switch them to “While Using the App.”
- Background App Refresh: turn it off for apps that don’t need it in Settings > General.
- Keyboard haptics: if you have them on, turning them off helps a bit too (Settings > Sounds & Haptics > Keyboard Feedback).
- Dark Mode: on the OLED displays of modern iPhones, it saves battery, especially at high brightness.
And before you change anything, check in Settings > Battery which apps use the most. Sometimes the culprit is a single app, and it’s easier to take away its permissions than to change ten settings.
When is a battery replacement worth it?
Apple recommends a replacement when the battery health shows as significantly degraded, when the iPhone has started limiting performance to prevent unexpected shutdowns and that bothers you, or when it can’t verify that the battery is genuine. If you still like your iPhone and everything else works well, replacing the battery through Apple’s service is usually much cheaper than buying a new one. The price depends on the model, and you can check it on Apple’s support website before booking an appointment.
My take
If you have an iPhone 15 or later, the charge limit is the setting with the best effort-to-benefit ratio: you set it once and forget about it. The rest depends on how much you use your phone. And one piece of advice: don’t obsess over the percentage. A battery at 82% that gets you to the end of the day is perfectly fine; what matters is how it works for you.
Sources: Apple Support: iPhone battery and performance, MacRumors.
