Some unlucky iPhone users got the short end of the battery life after updating to iOS 4.1. Users have reported battery life issues among other problems with prior firmware updates (remember iPhone OS 3.1?) but now some running iOS 4.1 are seeing their battery percentage drop to zero within hours.
Online discussion forums are hopping with activity from iPhone 4 and iPhone 3GS users complaining of shortened battery life and warm phones running iOS 4.1. Some reports have suggested that errant processes are running in the background constantly and draining the battery power. Bugs in the modem firmware, tethering software, and Game Center have all been cited as possible causes of the issue.
If you're not interested in shutting down several great features of your iPhone to extend and maximize your battery life until the next Apple firmware update is released, one or more of the following fixes should solve the problem.
1. The easiest thing to try is to open the Game Center app. Log out of your account. Exit the app then double-click the home button to bring up the multitasking dock. Hold down on the Game Center app until the icon wiggles and a red circle appears. Touch the red circle to quit the app completely.2. Some suspect that other apps could be causing the problem. Make sure all of your apps are updated to the latest version on your iPhone. Do this using the update button in the App Store or with iTunes on your computer. After updating turn the iPhone off by holding the sleep button and sliding to power off. Turn your device back on and see if there's any improvement. Some apps that have not been updated for iOS 4.1 might have to be uninstalled from your iPhone.
3. See if any apps are abusing Location Services. Turn off some or all of the apps running Location Services to check if one of them is causing the battery drain. Settings -> General -> Location Services will give you a list of the apps that recently asked for permission to use Location Services.
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4. Close open Safari windows. Touch the red circle on each open browser window to close the page. You can also quit the Safari app by double-clicking the Home button until the multitasking dock appears. Hold down on the Safari app until it wiggles and press the red circle to quit the app.
5. Do you use Internet Tethering? There may be a problem with tethering constantly trying to connect. To switch tethering off navigate to Settings -> General -> Network -> Internet Tethering -> OFF. To make sure connection attempts are stopped turn off Wi-Fi temporarily. Settings -> Wi-Fi -> OFF. Exit Settings then turn Wi-Fi back on at your convenience.
6. Some report that a hard reset (or several) fixes the problem. To hard reset the iPhone hold down the sleep button and home button simultaneously until the iPhone shuts off and the Apple logo appears.
7. We're not sure if this one helps with iOS 4.1, however it has been reported to help with previous firmware battery problems. Let your iPhone battery run down so low that the device turns itself off automatically (usually sometime after it falls below 5%). Now plug the iPhone in to charge and let it charge fully to 100%. This will recalibrate the battery.
8. Email accounts and Push could be the culprit. Try turning off Push by navigating to Settings -> Mail, Contacts, Calendars -> Fetch New Data -> Push -> OFF. Setting up email accounts can be a drag, but if turning off Push alone doesn't help this is the next step. With Push off, delete your email accounts by navigating to Settings -> Mail, Contacts, Calendars -> Accounts (choose the email account) -> Delete Account. This will not delete your actual email messages!
When all of your email accounts are deleted reset network settings, then reboot your iPhone by holding the sleep button and sliding to power off. To reset network settings navigate to Settings -> General -> Reset -> Reset Network Settings and confirm. Turn your iPhone back on and re-add each email account with Settings -> Mail, Contacts, Calendars -> Add Account. You can turn Push back on or test the battery life keeping Push off for the time being.
9. When all else fails you will need to restore your iPhone with iTunes. Plug the iPhone into the computer and sync everything. Afterwards, click the Restore button in iTunes with your iPhone selected in the left side menu. Make sure you select 'Set up as a new iPhone' when asked. This will wipe all of your settings and you'll have to re-sync music and contacts, etc. from iTunes when the process is complete. You will lose all of your progress to date in Angry Birds.
Although restoring as a new phone is more work, it's necessary to eliminate any problems in the backup that could be affecting battery life. Until Apple releases iOS 4.2 this November (or gets better at not messing up people's batteries during firmware updates) a full restore will probably be the best solution.