Well, all I can say is that while my battery usage numbers for Android System and Android OS are similar to everyone else's, my phone does not (for example) drain over night. Screen always on, bluetooth (connected to my watch), wifi, all on. Last night when I went to bed, phone was at 87%. This morning, 82%. If it were a lot lower, I would suspect some combination of apps draining the battery. I am a heavy user, so I don't expect my phone battery to last through the day. I charge it whenever I'm in the car.