In reply to ScottTalbot:
I use android sony experia z3 compact, dont bother with flight mode, but I do turn off the bluetooth and wifi, my battery lasts the full day and night, I normally charge the phone at night with my pocket powerbank thingy me jiggy, to be fair in the lakes its very hit and miss with signals, but the GPS works a treat, I also have a garmin sat nav that I bought off the bay, but to be honest my phone is better, lighter, good battery, multi function, good for tracking routes, so long as you dont try and track them using OS maps, have I mentioned that before
just give it a whirl, I saved a load of tiles for the lake district, so I have all the maps there that I need, cycle routes, ski routes and sat views, most of the paths are on there, its free, and also if like me, you go off piste and free style it, the viewranger is fantastic for telling you where you have been and where you are going, invaluble for when the clag comes in !!keeps your bearing to hand without having to get the map and compass out