I had a battery fail on a trip once, so I started carrying some small generic 2200mah battery packs. They weigh 2.2oz each and will recharge my phone...
My youngest son had this and would get a lot of ankle and knee joint pain when hiking with me. It made sense to me that a million years of evolution...
When I prepare meals, they can't cool down fast enough for me :D I heat my water to approx 180* and dump it into a ziploc with MountainHouse goodness...
Use the phone as you would on the trail for 10 days. That will give you a good idea of exactly how much power you actually need. 10K would enough for...
It looks like this hasn't been visited in a while and its a topic subject to updates. Plus I'm hoping to start my section hike soon so it's relevant...