How to enable Battery saver?

Use Battery saver mode to save power. It can reduce background activity of Apps, stop sync, and minimize system animations.
1. Go to battery settings.
2. Open Battery saver page.
3. Tap Save battery on the slider.
Note
You can also choose Balanced or Performance mode. Balanced mode is recommended
for normal use. Performance mode increases phone performance, but consumes more
power.
Tip
You can also swipe down from the upper-right corner of the phone to enable  Bat- tery saver on the Control center.