One of the key solutions to emerge after the iPhone slowdown saga was Apple’s promise of letting you check your iOS device’s battery health. That feature is here with iOS 11.3. If your device supports iOS 11, you should update to this latest version to get a more accurate handle on the health of your iOS device’s battery. If the battery health is not good, you can get it serviced to try and restore your device’s performance back to peak levels.
Make sure you’ve updated to iOS 11.3. You can check this from Settings > General > Software Update. If you’ve got an older version of iOS, tap Download and Install to update.
Once you’ve verified, go to Settings > Battery.
Tap Battery Health (Beta).
Now you will see two fields — Maximum Capacity and Peak Performance Capability. The first one gives you a percentage figure of your battery’s health. If it is 94 percent, then it means that your iOS device’s maximum battery capacity is 94 percent of what it was on day one.
Under Peak Performance Capability, you can see one of two messages — Your battery is currently supporting normal peak performance, or This iPhone has experienced an unexpected shutdown because the battery was unable to deliver the necessary peak power. Performance management has been applied to help prevent this from happening again.. If it is the latter, then you might want to get your battery serviced.
To disable throttling, you can tap Disable under the text mentioned in the previous step.
Apple says battery performance could suffer even if the maximum capacity is at 95 percent. In our case, peak performance was normal at 87 percent. We tested this on three devices — iPhone 7, iPhone SE, and iPhone 5s — and it worked on the first two. This feature didn’t show up on the iPhone 5s (also running iOS 11.3), which is now four-and-a-half years old.