There are quite a few guides on how to improve the iPhone 4S / IOS 5 battery life. If you are just starting to research this search for:
- Disabling APP Notifications
- Disabling Location Services
- Disabling System Services
I found a new one this week – disconnect your AT&T MicroCell. I don’t know what the cause of this one is, but my battery drain slowed to about 25% of the rate before with the MicroCell on. I was never really happy with the MicroCell, and it literally sucks. My reception and call quality is actually better now without it.