So I'm going to be doing some trekking in the near future with a buddy who's also into photography, and the route we're on includes a 3-4 day stint where we will not have access to power. Between the two of us, we'll probably have 3 cameras, all of which use different types of batteries - E-M5, E-PM2 and Fuji X-E1. Rather than buy 4 or 5 batteries for each camera, we were considering getting an external battery pack, and using that to recharge our camera batteries nightly (we have chargers that run off 12V adapters) I've seen plenty of reviews that tell how well such devices work for phones and tablets and such, but does anybody have experience with how they work for charging cameras batteries? Any recommendations would be quite helpful. Thanks!