It sounds like you plug in the iPad to charge, but the charged percent does not update until you restart the iPad. I want to recommend a few things here. First, close all the apps:
- Double-click the Home button.
- Swipe left or right until you have located the app you wish to close.
- Swipe the app's preview up to close it.
From: iOS: Force an app to close
When you have done that, reset the iPad:
Resetting your device
If your device stops responding, you can reset it by pressing and holding both the Sleep/Wake and Home buttons for at least ten seconds, until the Apple logo appears.
From: iOS: Turning off and on (restarting) and resetting
Then test the issue again. If the battery indicator is not updating correctly, I would next backup your iPad to iTunes and restore from your backup.
iOS: How to back up and restore your content
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I rebooted it (by doing it properly and not just turning on and off) as suggested and the indicator is working fine. It is actually going down as time goes by. It used to sit at a number and not go down and then suddenly drop 25%... I am still waiting for it to go really down to recharge it and see if my initial problem is solved, but it seems to be working ! So many many thanks, I would come back here and give you an update once I charge it!