I highly recommend the Goal Zero guide 10+. Although I havent used mine a lot (only had it a year) it seems to be the solution for phone charging.If you use your phone as a gps with something like the Back Country navigator app you have to charge it frequently. The battery pack will charge AA and AAA batteries and then use them to charge your phone or run a headlamp, radio, etc. I plan to use mine more next year and hopefully it continues to impress me, but so far its the best thing I can find.