Battery Percentage Bugging?

Hello,

Long Version :

I've an iPhone 5s it was working perfectly on iOS 9.2 till I updated it to iOS 9.3.3. When I leave it charging and unplug it I realize that the percentage is still stuck at the one I unpluged the phone (After playing games, watching videos and using it with full brightness for a long time) When I restart the phone the percentage change (depends when I restart it : If I restart it immediately after I unplugged the charger it always increase by 4-5% and come back normal but if I use it for a long time and restart it come with less percentage). I tried changing charger but nothing. I also bought a new iPad mini which was on iOS 9.2.1 and updated it (used the same charger as iPhone) and the same problem happened. I tried to recalibrate the battery but nothing happened so : Please help me to solve the problem because it's annoying to reboot the iDevices at every charge/synch.

Short Version :

My iPhone 5s and iPad mini 1 have always stuck battery percentage after charge (after updating them into iOS 9.3.3 and 9.3.4) till I reboot them, they increase by 4-5%. I tried battery calibration, changing the charger.

Thanks to help me.