Marc Posner wrote:
Personally, I think the root of the battery issues is the phone's (and iOS 5's) persistence in trying to accomplish a task - when it really should just give up and move on. Bad contact? Stop trying to import it. Bad calendar reminder? OK, put up an error message and move on. Can't connect to the network? Fine, give it a few seconds instead of a millisecond. ...
Sounds reasonable. I discovered that problem on my old iPhone 3G years ago when it tried downloading a big email attachment (via 3G cellular) over and over (while failing) all afternoon. The battery died quickly. After that I changed my POP settings to manual/manual and all was well. I still use Exchange with Push, and haven't had a problem.
I've been getting great battery life on my 4S but I wondered if it was due to my WiFi connection. So yesterday I switched off WiFi and let it run, with a new full charge, on 3G overnight. Little use, but considerable standby, and lots of battery left (91%), all on 3G:

The settings are all the same as in a previous posting I made on page 179 of this thread:
Notifications - all on (not only in the Notification Center, but also for badges, lock screen, etc. including stock market and weather)
Location Services - On are camera, compass, find my friends, maps, siri, find my iphone. System services - all on except Time Zone and Traffic
iCloud - on for contacts, calendar, reminders, photostream, find my iphone. Off for bookmarks, notes, documents and data
Mail - two accounts: Exchange Server for mail with push. A POP account set to fetch-manual and advanced-manual
Bluetooth off
iTunes WiFi sync - on
Siri raise to speak - off
The phone was activated at the AT&T store where I bought it, and then I added apps and music via iTunes. I did not "restore" it, I don't think.