I typically have everything ON on my phone (GPS, BT, wifi, etc.). In the last couple of days I noticed a lot of GPS activity when I'm at work (away from home location) and increased battery drain. I have my phone fine-tuned, the only periodic update is Weather app and even that one setup not to use GPS. So what the heck? I didn't install any new apps. Start analyzing what's going on (GSam wasn't helping either), and just realized that by mistake I enabled Google Now a few days ago. So, whenever I'm away from home, it constantly pulling traffic info, estimates of how long it takes to get home, and other stuff. And considering that I'm at work in a building where GPS signal doesn't come through everywhere, it's constantly searching thus draining my battery. So, just disabled it and problem seem to go away!!! Hold Home button, select Google, go to setting and turn Google Now service off.