The battery saving mode worked good in my opinion. Once it dropped to 15%, the whole interface becomes orange.. Like a warning sign. I used it constantly (screen on) after it dropped to 15%.. I pulled off about an hour with constant screen on, playing a game! I'm sure it's impossible without the battery saver mode. My opinion is if it drops below 15%it would easily last for about 2-2:30 hrs mixed usage..