Further to Edelweiss’s comments on power consumption, I use an iPhone, and I spend a lot of time backpacking, so I’m sensitive to power consumption when out of cellular range and when sometimes using the GPS chip.
Until a couple of years ago (I forget exactly which iOS), toggling airplane mode also toggled the GPS chip. That made things somewhat more complicated, because if you wanted to use GPS you had to worry about a lot of other stuff that was consuming power when you turned off airplane mode. Now you can just leave it permanently in airplane mode in the backcountry, and you control the GPS chip by turning Location Services off or on.
To optimize power consumption for hiking out of cellular tower range:
- Turn on airplane mode (no searching for nonexistent cell signal; WiFi search and many other things stop without you having to disable them individually)
- In Settings\General\ turn off the master switch for Background App Refresh.
- In Settings\Privacy\ go to Location Services. With the master switch on, go down every app individually and turn it off, except the mapping app that you are actually planning to use. Don’t forget to go into the System Services submenu and turn everything there off too, although you can leave “Find My iPhone” on, it makes no difference. Now you can use the Location Services master switch to turn the GPS chip on an off as you need it.
In airplane mode and with the GPS chip off, I comfortably get a week from an iPhoneX using it for the camera and a bit of reading with the screen brightness low after dark. Using it for constant GPS tracking will drain the battery much more quickly, I tend to only use GPS only occasionally when I want to check my position.