I switched to my iPhone GPS to reduce gadgets/weight, but my Garmin 60csx is much more battery efficient - screen and GPS running full time and the Garmin will last nearly 3 days on 2NiMh Eneloops. I keep the iPhone's radios and GPS shut down and only turn them on to spot check/confirm location a few times a day. Now carrying an Inreach sat com/tracker which will last a nearly a week running full time. No map on my Inreach, but there's one built to the app and all data pairs into the smartphone via Bluetooth when I periodically link them. I mostly rely on paper maps though, and only use the GPSs to confirm.