Want to charge your smartphone during your hike? It could prove utterly important to receive a gps-signal during a white-out.
Many carry a mini-solar panel, which have become increasingly efficient over the last couple of years. You can mount it on your backpack and charge while your walking. However, if it is cloudy or you walk inside a forest, it’s not very potent. If it isn’t angled nicely toward the sun, the charging capacity also drops considerably. But if you’re taking a break and the sun is out, it can be very useful when placed in the sun and angled directly towards it.
A battery-pack is maybe more interesting if you ask me, due to it’s versatility: you don’t have to sit around for 2 hours in the sun to charge your device. And you can charge it when it’s cloudy, inside your tent, at night or during a white-out. You’ll get 2-4 smartphone charges on a battery pack and just have to remember to re-charge the thing, once you’re in civilization. The weight is likely similar to a mini-solar but the volume is probably smaller.
Best electricity advice? Save power. Turn your device off when not in use and always turn off your GPS unless for that 1 minute when you need it, since any GPS receiver is super hungry. That also goes for you camera, if it has a GPS-tagging feature in it: consider turning that function off.