I've just started seeing this problem now in the past few days.
When I unplug the charger, either the battery charging icon stays on, or the "Battery full, unplug charger" notification stays there.
The big problem is if I turn off the phone. After shutdown, the screen stays on showing two different icons (changes between them every few seconds). One icon is a battery half full or so, the other is an empty battery with a yellow triangle and a icon of a thermometer next to it.
When this happens, I can't turn on the phone. The only way I can turn on the phone when this happens is to plug in the charger, start up, then remove the charger again.
I'm on rooted KG2, XWKDD kernel. Bit worried about this, I'll try another ROM & kernel but I don't think it's software related?