Right after upgrading my iPhone 4 to IOS 5 I noticed my battery draining much faster than on any of the IOS 4.x versions. I found several postings where people have tried the following with varying success. I tried the following with no change in battery drain. 1) Reset Network Settings: Tap on Settings > Reset > Reset Network Settings 2) Disable Bluetooth: Settings > General > Bluetooth > OFF 3) Disable Notifications & apps: Settings > Notifications > Turn OFF 4) Disable Timezone Adjustment: Tap on Settings > Location Services > System Services > Setting Time Zone to OFF 5) Disable Location Service: Settings > Location Services > Disable 6) Disable Ping: Settings > General > Restrictions > Enable Restrictions > Ping > OFF 7) Disable Diagnostic & Usage Reports: Tap on Settings > General > About > Diagnostic & Usage > Dont Send 8) Deleted iCloud account from the phone and stopped all iCloud syncing. 9) Disable Email account/s by heading to Settings > Mail, Contacts, Calendars > Account Name > Delete Account. After completing or verifying 1-9 I again reset network settings and rebooted. Then I re-add my accounts: Settings > Mail, Contacts, Calendars > Add Account. If there's some code bug what I did above shouldn't have accomplished anything, and it didn't. Two days later I resorted to a hope based strategy and did full restore on the phone and still the power drains. Even during the night on standby with no apps running the power drops ~20% over 8 hours. I used the app "System Status" to see if any processes were still running except the 14 mobile user procs, 13 root procs, 1 mdnsuser proc, and 1 wireless user proc. I called Apple support and put in a ticket. They offered to replace the phone but after thinking about it I thought why? The phone worked flawlessly until the IOS 5 update. Apple has some work to do here and I hope it is soon. If I've missed something or anyone has any suggestions they would be welcome.