Lately, I have been experiencing this. It happens randomly. For my phone, it stops charging when it reaches 50%. Most of the time, it charges all the way to 100%, but sometimes it just gets stuck to 50%. I'm using the D4 charger that came with the phone because it suddenly doesn't recognize the charger from the OG Droid. I have used the old charger then, but couple months later it stopped working.
Any of you have experienced this and have fixed it? I repeat, it only happens sometimes. I also made sure that the charger and cable is not faulty. I'm plugged straight from the outlet as well. In addition, when it is plugged, both the on screen and battery icon on the top right shows that is indeed charging.