iPhone Repair - iPhone 5 battery life problems typically surfaces after every iOS update is abnormal battery drain. You’ll notice if your iPhone battery life drops after installing the iOS 8 update, but in any case you can expect 8-12 hours of usage on the iPhone 5s, iPhone 5c, iPhone 5 and iPhone 4s. This all varies based on your device and how you use it.
1. Find apps using your Battery life to see what apps are using your iOS 8 battery life, go to Settings -> General -> Usage -> Battery Usage.
2. Turn off background app refresh Go to Settings -> General -> Background App Refresh -> Turn it all off or off for individual apps.
3. Turn off push email : Settings -> Mail , Contacts, Calendars -> Fetch New Data – > Choose the setting for each email account.
4. Turn screen brightness down: Settings -> Display & Brightness -> Auto-Brightness -> Off. Normally