I’ve only had my iPhone 4S for a week but I noticed early on that it was sucking battery juice much more rapidly than my iPhone 4 with the same apps and iOS 5 on it. Unfortunately, we lost power for almost a week so it was tough to get it charged regularly to test various things. Today the power came back and I was on the phone with Apple and we made the appointment for me to get down to the Danbury Apple store to swap the phone for a new one.
But, Patrick, my excellent Apple phone support person asked me if I’d tried backing up the phone, then using iTunes to restore it to factory settings minus my apps and data. In other words, clean it off and reinstall iOS 5 from scratch. No one had recommended I do this and he thought if I did it it might give me a baseline to see if the problem with battery was my apps sucking juice, iOS 5 sucking juice, or underneath it all a problem battery.
It was worth a try so while we were on the phone I backed it up again, then reset the phone to factory settings reinstalling iOS 5 in the process. I did not migrate my stuff back.
I got on our network, got it on our AT&T micro-cell, got it up and running, charged it to 100% and put it to sleep and went outside to carry the bags of now defrosted tomatoes from our garden to the trash (boo, we lost all our frozen vegetables).
I came back in an hour later and the phone was still at 100%. This was a good enough sign for me and I then synced all of my apps and stuff back on, checked things out to make sure the sync worked correctly, charged back up to 100%, put the phone to sleep and went outside again.
Two hours later the phone is at 97%. This is a great sign.
I may still have a problem phone and given my calls to Applecare I’m sure I’ll be able to swap it for the next month, but, I’m going to stick with it for a while and wait for the iOS 5 update to come out and see what happens.
The short of it is, if you’re not getting what you think you ought to out of a charged battery try reinstalling the system, it may help. It can’t hurt.