Even though the Apple claimed that (If your iPhone 6s or iPhone 6s Plus battery percentage doesn‘t update) they fixed the issue in iOS9.3 there are so many reports claiming that the issue is back on iOS10.
We post a detailed post about how to fix the better issue in a post here. How to fix iPhone shut off unexpected and shows battery low sign but there still have 80 % remain. No any official fix for this yet from Apple unfortunately.
As I detailed on the post you can replace your better from Apple if the issue continue to happen on your phone and if your iPhone is eligible to do so.
On the Apple support page they noted that
Learn what to do if the battery percentage doesn’t update on your iPhone 6s or iPhone 6s Plus after you manually change the time or change time zones when traveling.
So one solution to this is as follows:
- Open Date & Time Settings.
- Toggle the switch for Set Automatically Off and On multiple times or switch Time Zones.
- Restart the iPhone