Follow these steps to find out if your battery is failing.
Make sure the phone is fully charged before beginning.
- From the home screen, tap Phone.
- Dial *#*#3424#*#*
- Tap ACCEPT.
- Tap More.
- Tap Battery Test.
- Tap RUN.
- Tap the Back key twice.
- Leave the phone alone for an hour.
If, after the hour test is complete, the battery has dropped less than 30% of its total charge, it is deemed to be working within acceptable limits.