I was hoping to get some feedback on a good backcountry portable charger. I'd be using it mostly for charging my phone that I use for my GPS. I've considered two options so far: GOAL ZERO VENTURE 30 and Dark Energy Poseidon. Any one used either one of these? The Poseidon had more MAH's. Goal Zero seems to have been around longer though. I'm also wondering if the Poseiden would work fine with some of Goal Zero's solar chargers. Any advise or other recommendations would be great. Thanks!