Any suggestions for a cell phone charger for a 10 day trip? I want to use my phone as a camera for spotter pictures. My requirements are light weight and can charge multiple times.

Check Amazon for the price of batteries. You might be able to buy a handful of them for less money than a charger. Otherwise, I'd go solar.

My hunting partner just picked up one of these:

https://darkenergy.com/?gclid=CJyvtY2cis4CFY47gQodGhICkw

If using a iPhone or other popular smart phone check for a case with a built in battery. Only for pictures? How long does a full charge normally last on your phone? A few changes can greatly increase battery time. Put it in Airplane mode, lower the display brightness and find the quickest display timeout you can live with. If you are familiar with your app settings turn off every thing you do not need.

Going the portable chargers route your average smart phone takes 4,000mAh to fully charge, 5 recharges would need require a 20,000mAh charger and will weigh around a 16 oz.

I bought a portable solar charger which worked if on a stand but not when moving.

http://www.digitaltrends.com/mobile/best-portable-battery-chargers/

The third unit shown in this article would work if on the move it could be left at camp to recharge it's self while you are hunting and has twice the needed power to recharge your phone every night. At $37 it seems to good to be true

I bought this one a year ago and like it so far.

https://www.amazon.ca/ALLPOWERS-10000mAh-Battery-Charger-Samsung/dp/B00MEC4MV0

The description says this:
"Solar energy technology, could charge itself under sun for emergency"
That word 'could'. Does it charge itself? If not, what good is the solar?

Yes it does, it just takes quite a while to charge. More of a trickle, so I try not to rely on it. But it does work.

I bought a 5 watt solar charge from amazon that works extremely well, especially if you place your phone on airplane mode. Its called blkbox.

I used to rely on cell for camera but I had it shut down a few times in AK, once when I tried to film a moose fight.... it was NOT low on charge, had 97%.... and it wasn't all that cold, probably 25...

That said we have a couple of brunton solar panels that work well. IF there is light.

And Carolyn carries a charger that uses AA in a pinch for her real camera batteries.

Depends on how much weight you can take.