As you’ve noticed from playing Pokemon Go, it quickly drains your battery. To prolong your battery life, we recommend buying a battery pack for your phone. However, if that’s not an option, you can also turn on the app’s Battery Save mode, which you can switch on in the settings screen. However, this mode just fades your screen to black when not in use, though it may be helpful if you’re just walking to hatch eggs.
Originally Posted by: gamespot.com