cactuscat wrote:charge my phone/devices 10 times
Where are you going that requires that kind of capacity?
On our recent Royal Arch trip (5 days / 4 nights in the canyon), I made it with the Anker 3350mA battery. It weighs just 3oz.
I ran RouteScout for the entire hike, took 351 photos, listened to some music, etc. My 2.5 year old iPhone 6 doesn't have the same battery life it did when new, but I was 43-55% remaining in the evenings, and charged to 90+% before bed using the Anker. It was empty on the 4th night before I got a full charge so I used another Anker I had brought with me just in case. But I would have made it back to the trailhead the next day on the charge I had so it wasn't totally necessary.
That's just my experience. Devices, use, etc. will be different for everybody.
But for the price/weight/size/convenience factor, I highly recommend it. See Amazon
This extra battery is now standard equipment anytime I go anywhere. It's as important to me as a headlamp and firestarter as emergency gear.
(Slightly larger at 4.2oz, I have this one
too but I almost never use it because the other one performs so well.