5v, 700mA in the worst case?
You could run it for about 2 hours, then, from one of these:
Hell, say the max power is vastly overestimated and you could get 20 hours. Still not very much for a device that's in a remote location without basically sticking it on a car battery.
The battery my company just paid £70 for to run a 1500W server UPS could probably manage only a week once you took voltage conversion and uneven power usage into account.
I don't think it would really be very suitable for that job (unless you have a huge solar panel to keep that thing charged all the time), but obviously more accurate usage numbers would be available once they start shipping.