[Lurkina.n.Learnin]

It has been my experience that when you get out of range of cell towers your battery life plummets. Seems like the phone goes into hyperdrive looking for a signal. I used to charge my flip phone once a week but when I went up in the woods to work on a truck if I forgot to turn my phone off the battery would drain in a few hours. That was with several different brands but I have never had an iPhone.

[Yosemitest]

Unless I need my phone and I'm between restocks, it'll be in sleep mode most of the time to stop the tower pinging.
That's why I'm leaning more towards the I-Pad, and because I'll use it more for a computer to edit video, and type a log or journal, for later own, when I might want to compile it into something else.