Why is iOS 5 draining my battery so fast?

My wife's phone went from lasting a full day to needing a recharge every few hours after upgrading to iOS 5. Mine still works fine after the upgrade. What might be causing this?

Solution 1:

I think I've found the answer for my case. Location services were completely innocent, and I've returned them to default settings. My phone synchronises with a Zimbra server, set up as an Exchange account. The update enabled sync of Reminders, but the Reminder sync didn't work. Removing Reminder sync from the Exchange account setup has stopped the battery level dropping while I watch.

My general advice is to check your mail accounts to see if anything new is being synchronised, and then disable it if you're not using it.

Edit: added image showing Reminders control.

Solution 2:

After upgrading to iOS 5 I noticed a huge battery loss compared to normal (10% per hour) and my iPhone was regularly warm to the touch. The steps that resolved this issue for me were resetting all network settings (this restarted the iPhone) and then erasing all email accounts, including iCloud, and manually re-adding them.

After performing these steps my phone immediately cooled off and the battery was stable once again. Your mileage may vary.

Solution 3:

To fix the battery drain issue:

1. Go to Location services > System services
   Everything should be OFF in there.
   Also limit apps location service for those which you do not use frequently.

2. Notifications, disable those you do not use.

3. iCloud, set to sync manually now and then over WiFi.

4. Disable Ping
   Go to Settings > General > Restrictions
   Enter 4 digit pass code.
   Scroll down to Ping settings and disable it.