Pokemon GO uses Battery Life. It's not very effective.
Pokemon GO is quickly draining smartphone batteries
Pokemon GO is out now in Australia and New Zealand, and there are even international workarounds if you want to play in other regions. But wherever and however you play, don't forget that catching them all is absolute hell on your smartphone battery. Several reports make it clear Pokemon GO can drain your charge in no time and all - an issue Niantic Labs is already working on.
"Some devices may experience battery drain while playing Pokémon GO for prolonged periods of time," Pokemon GO's official known issues page reads. "We are working on a solution."
Pokemon GO's game settings do have a "battery saver" option, although it's not very effective. The good news is fans are coming together to provide tips on the Pokemon GO database, such as manually adjusting the screen brightness or switching the sound off. Hopefully Niantic will have some better official fixes soon so players can get back to catching them all.