As noted by TimothyH, you need a recreational grade GPS unit.

I use a Garnin 62 or 64 series GPS. (I own a 62S and later also bought a 64.) Screen is too small for serious route planning before you leave, but it is big enough to see where you are and where you are trying to go. You can install maps with aid of a computer before your trip, several sources of maps available on the internet and some are topographic maps. Most of the better recreational grade GPS units have a slot for a micro SD card. A 16 or 32 gig card can hold a huge number of maps.

Runs on AA, you do not need the big battery pack. My Garmins are configured to time out the screen in 30 or 60 seconds to save battery. But I get very good battery life on Eneloop batteries and Ikea Ladda batteries. I have a dynohub and USB charger on my bike, also have an AA/AAA charger from USB capability. My last couple tours I was self sufficient for power (never plugged into an outlet, all power used was generated by dynohub). The Garmins will run with the screen backlight turned off when you have good lighting (sunlight, light overcast, etc.) so that helps battery life.

Most of the time the phone was off or in airplane mode, so that was not a big power drain. But it would be a good idea to load some basic maps onto your phone as a backup. Photos are of the same Garmin 64 but photos are of two different bikes.



The mount in the second photo was a DIY mount that attaches to the stem cap bolt.