Ipad mini doesn't charge to 100%?what is with it?
This is a fault in the battery. If it is able to let in some charge, it means the charger is alright and that you should have the battery replaced. This is because soon or later it will not be able to receive any charge.
It might be the cord. I had a defective iphone cord before that prevented it from charging 100%. When I switched to a different cord the slow charging, never to 100% problem went away.