If you changed the time on your iPhone 6s or 6s Plus manually or traveled to another time zone, you might have noticed that your battery percentage has not updated properly. That is what people are complaining about on the Apple Support community forums. Apple acknowledge it and decided to create a page for the information on how to fix this issue.
Here is what you need to do :
- Restart your iPhone.
- Go to Settings > General > Date & Time and make sure that Set Automatically is turned on.
Apple Support also encourages users to contact its staff, in case the issue persist.