I don't plan on doing anything bigger than day hikes in the WMNF. Running an AllTrails route recording Saturday, my phone got to the critically low stage after around 6 hours, when normally it lasts 2 days.

I think I'd like an external battery that I could attach to the phone with some hard protection for the connection, and some way to connect the pair so that I'd just have a supersized phone that would last a long time. I did not find such a thing.

I'm kind of leaning towards just getting the one that has a 2000 lumen flashlight built in, and can jump start my car since it would be nice to have those things for life unrelated to hiking. Just recharge at lunchtime, instead of leaving the brick connected I guess...

If you don't mind an external battery that you need to connect to your phone with the cable, Anker makes a really nice one for about $15 on Amazon. It's a little bigger than a pack of gum, and charges your phone one to two times.

link:
http://www.amazon.com/Anker-PowerCore-m ... ords=anker

Another option are the iPhone cases that have an external battery built into them.
These are more expensive, that have the advantage of no cable needed, a little more robust construction, and offer more protection for your phone. Try an Amazon search for < iPhone battery case >

link:
http://www.amazon.com/Battery-Anker-Ext ... ttery+case