This is a persistent problem I am facing these days. It is a new iPhone 6, so this is not exactly a battery age issue. When I hit 100%, the indicator freezes at that number. It does not move down until it shuts down when battery is completely empty (no warning, still standing at 100%). What might be the issue?
Hard iPhone user here, make sure the date and time correctly synced
1.go to Settings > General > Usage, turn Battery Percentage off and then turn it back on.
2. Update iOS to the newest version.
3.let the battery drain completely until the phone turns off. Charge it, and once it’s charged, turn it on
May be it battery issue, you need to replace it
iPhones are very smart devices, however, they aren’t really free from errors. Software and hardware bug could occur to a device at any time, and the last year iPhone 6 generation happens to face weird trouble – the battery percentage on the top bar of the display gets stuck at 100%. The battery on the phone discharges by the regular amount, however, the battery indicator doesn’t indicate it.
Try these steps
- Restart the Device.
- Update the iOS Version
- Hard Reset your iPhone
- Reset to Factory Settings
Hope this helps.