Doug

I have been working out of cell range for the last two falls in northern Canada as a Survival Consultant for a US TV Show and using my iPhone for supplemental topographical maps (Topo Canada) and air photos (Gaia GPS) when out in the field daily. Although it works well in airplane mode (we have no cell towers near us), I can say that you would not get more than two days' use out of a phone. I often come back at night and even my new iPhone 13 will often be down to 65% at the end of the day and that's just taking a few pictures and checking navigation from time to time each day. Heavy use will bring it down to 40%.

I think that emergency satellite connectivity will add to the phone's daily power use and it's one of the reasons I carry a beacon, GPS receiver and in my safety pack power pack to recharge my phone and beacon if stranded overnight.