Q: Battery charge indicator stuck on 100%

This issue can occur on the iPhone 6S or iPhone 6S Plus if you've manually changed the time on the device or changed time zones while traveling. Apple is aware of this issue and will fix on a later OS update. In the meantime, here's the fix:

Restart the device. From the Home Screen, tap Settings > General > Tap Date & Time. Ensure Set Automatically is enabled

https://support.apple.com/en-us/HT205727