Droid 4 Reading Full Charge, But it's not

[Boylanca]

I've had this problem for a few weeks now, and it won't happen all of the time, just about 50/50. When my phone will run low battery, I'll charge the phone... I've used the charger supplied with the phone, a non motorola charger, and through the computer, so I'm pretty sure it's not a charger issue. I will plug the phone in, check it about 20 minutes later, and it will have gone from 5% to 100% please unplug your charger to conserve energy. But I'll unplug it, and it'll immediately drop to 50%, then after a few moments, It'll drop to 20%, and it'll start the whole process over. Sometimes I have to do this 4 or 5 times, and even then I don't know if it ended up at a full charge or not. What's puzzling is, there are times when it'll charge like normal and take a couple hours, and be fully charge. I've searched the forums, and haven't been able to find anything on this. I apologize if it's been answered before, but any help is extremely appreciated.