2) iPhone Background App Refresh and Battery Life
You can choose which applications you want to auto-refresh when not in use. Being selective about which apps refresh their content on their own can save significant battery life. If you know you won't need certain apps, turn off their background app refresh options.
To do so, go to Settings > General > Background App Refresh and scroll down to the apps you want to modify. To turn off app refresh, flip the switch next to the appropriate app into the Off position.
If you're particularly concerned about battery life, you can disable the setting altogether by flipping the master Background App Refresh switch, at the top of the associated settings page, to Off.
3) Strategic iTunes & App Store Settings
You can save battery life by being strategic with your iTunes & App Store settings. For example, you can turn off auto downloads individually for new music, app, book and app updates, or you can disable them all. You can also choose only to auto download when you're connected to Wi-Fi, to reduce battery drain and cellular data usage.
To modify your settings, got to Settings > iTunes & App Store and then flip the switch next to Music, Apps, Books and Update into the Off position, if you want to disable them all. Flip individual switches to disable only the options you want to turn off. At the bottom of the screen, flip the Use Cellular Data switch to Off if you want to only use Wi-Fi for auto downloads.
4) Wi-Fi, Bluetooth and iPhone Battery
Apple's iPhone battery tips page suggests that enabling Wi-Fi saves battery life. But this is not necessarily accurate.
If you're at home, the office or somewhere else where you want to connect to Wi-Fi, you can use less battery life on Wi-Fi than using only the cellular network. However, if you're traveling or even just walking through the mall, entering and exiting the range of multiple open Wi-Fi networks but never actually connecting to them, you can unnecessarily drain battery as your device repeatedly scans for, and sometimes attempts to connect to, random networks.
If you're concerned about battery life or you don't plan to use Wi-Fi, turn it off by going to Settings > Wi-Fi and then flipping the switch into the Off position.
The same goes for Bluetooth. Some apps on your phone use Bluetooth to sync periodically with devices or services, including the popular Fitbit app. If you're worried about battery life or know you'll be somewhere without a power source for an extended period of time, you may want to disable Bluetooth. (Settings > Bluetooth, and flip the switch to Off.)
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