Just wanted to confirm this. After the iOS 5 update, my iPhone 4 gobbled up the battery and sometimes ran hot in standby, even when switched to flight mode (I noticed this on a transcontinental flight of 5 hours, which drained the battery from 100 to 50%). There were also lots of error messages in the diagnostics log under General/About. After a "Reset all Settings" as described above, everything is back to normal, and no more errors. Go figure ...
I followed the advice above and did the following after seeing my phone drain about 4% an hour, even over night. Woke up to a dead phone.
1) Turned off certain location services that seemed to be "on all the time", mainly "Setting time zone".
-no change
2) Recharged it to 100% in one go and leaving it in the charger for a long time after reaching 100% to recalibrate the battery.
-no change. Still drained 4-5% an hour on standby.
3) Reset all settings then restore from icloud and do a restart or two. Did not sync music/video to device yet.
- Better, still got "Setting time zone" turned off, otherwise everything is on. I have not synced my media(music/videos) yet because I want to test if the change worked first. So far I've gone some time with the phone in standby and very light use and the dropping is better. But still atleast 3% per hr in standby mode.
I have about 8-10 apps "running" while in standbymode by the way.
4) Tried a DFU reset, only thing I did was download contacts and a few other things from icloud. Otherwise no syncing. Problem still there. No apps running, no additional location services other than a few of the apple ones. Still losing 1-2% per 30mins.
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