There has been quite a few reports on the new iPhone 4S battery drain issue. The dropping rate is approximately 1% per minute and before you know it’s time to charge up again.
Once fully charged and this issue occur again. You will need to perform diagnostic testing.
1. Reset to factory setting
2. Restore iOS (itune)
If none of the procedure work then you now got a logicboard problem.
Solution – Take it back to Apple my friend!