Viajero, I have a Droid Maxx, which has probably the longest battery life of any phone on the market. But using GPS, even with having downloaded the coordinates offline is draining. I sometimes go out for a whole day of hiking and caching, so would rather conserve for an emergency. The second is I've been venturing into areas where there is limited or no cell service. Sometimes I can get a text message out, which is better than nothing. I always let my family know where I'm going, leave the coords I'm hunting and when to expect me back. I'm planning a weekend primitive camping/hunt in the mountains so a GPS, along with a Sat phone is necessary. There is zero service.