Nokia Lumia 735 - Use Battery Saver to conserve battery life

If you’re away from a charger and want to conserve your phone’s battery, then go to Settings – Battery Saver. A heart symbol should appear over your battery indicator.

This turns off various features such as push email, and some Apps will be prevented run in the background.

When it is turned on, you can also press Advanced at the top of the screen. From here you can choose when the feature gets automatically turned on, or whether it should be used permanently.