When you turn Battery Saver on, your phone automatically turns off some services and features that use battery in the background.
On the Start screen, tap .
If you want Battery Saver to turn on whenever the battery gets to 20%, select
Always turn on Battery Saver when battery is low.
If you want to turn on Battery Saver now and leave it on until the next time you recharge the battery, select
Turn on Battery Saver now until next charge.