From the XDA Developers Forum, I have implemented this solution successfully on my Samsung Galaxy S Epic 4G (with GingerBread.EI22 and also GingerBread.EL30), which has eliminated the "Battery fully charged. Unplug charger" notifications from my phone. The solution offers the following three features:
- Stops the vibration.
- Silences the sound.
- Prevents the screen from turning on in the middle of the night.
Best of all, you may choose to implement any (or ALL) of the three features above. Good Luck!