After each iOS update, a small portion of users reported dramatically reduced battery life. There are a variety of causes for this issue, and a corresponding long list of fixes, including disabling location services, checking Internet tethering, deleting problematic apps, turning off Push, calibrating the battery, closing extraneous Safari windows, and restoring.
Several users have now reported success with the following procedure, which may alleviate one of the most common battery-drain factors in iOS: a problematic Push email account.
- Delete your email account(s) in Settings > Mail, Contacts, Calendars > Your Account > Delete Account
- Reset Network Settings in Settings > Reset > Reset Network Settings
- Reboot your phone by holding the sleep/wake (top) button then sliding to off.
- Re-add the email account Settings > Mail, Contacts, Calendars > Add Account…
- Turn push back on