I have come to the conclusion that when the internal sensor believes the battery to be fully charged or very close to it, the charge function is turned off totally. This is done internally to the phone. The only way that I can get a full charge is to unplug it for a few minutes and then plug the charger back in. I can eventually get a ding to indicate a full charge, but the screen only shows 99%. 100 is all but impossible.
Right?? It's crazy. If I use a regular charger, it will drain as fast as it charged once it's reached full. The only way I can maintain a 100% charge is the use a rapid charger.
i use a rapid charger from my Flex 2, the stock one that came with the phone is next to my bed and a older charger for my M7 is at my girlfriends..they all push the phone to 100% without any issues other than one does it faster than the other 2.
Yes I had the same issue when charging thru USB cable on laptop. In fact the charge went to 0% on my new M9 just purchased yesterday
there is also a know (pretty sure its known) bug with charging this phone..not all see it though..i have had it happen maybe once or twice since i picked up this phone..others have came across it much more than that..it will need a MR fix to be kicked from HTC to fix this though.