> Well, a 60W/h battery would, in theory, power it for one day. I'd use something like an old motorcycle batter. (12V 10Ah) Which might run for 2 days continuous.
I do this currently with a raspberry pi in the front of my backpack, using a 4500mAH lithium ion battery I bought off Amazon. Works great. It gets about a 12 hour charge so far, but I haven't really been keeping careful track of battery life.