>>345489How few photos do you take if you switch off your phone in between shots? Smartphones take a while to boot up, not exactly helpful when trying to take a quick snapshot. Turning on the camera, specifically due to the fact that smartphone cameras have a live video viewfinder on their large LED displays, drains the battery fast too. I can just about get a days use out of my Nexus 4 using the camera and the mapping software (OS maps stored locally so no data connection required) plus sporadic GPS (if I'm cheating that day).
I got myself a battery pack recently, for multi-day trips. Weighs a lot, almost half a kilo, but I wanted one that was going to do me for trips up to a week long. Got this, the capacity is 22400mAh which I put at just over 7 full charges of my phone. Been great on the 2 day trips so far and the battery indicator seems to match my expectations.