Amazon has Powerfilm AA chargers on sale.  If you’re running LD NiMH (Eneloops) this is a nice solar charger.  VERY portable.  I have no connection, just a fan of the product.

https://www.amazon.com/PowerFilm-AA-Foldable-Solar-Charger/dp/B001RMF7P8/ref=sr_1_18?ie=UTF8&qid=1486742013&sr=8-18&keywords=powerfilm solar AA&tag=vglnk-c102-20

The Output is 2.2 Watts, supplies 3.6V DC at 0.6 Amps


check reviews.

It’s an ultraportable dedicated AA battery charger.  I own several of them and they work great.  I think this thing is in a class by itself.  

Powerfilm
https://www.youtube.com/watch?v=VArRx6voKK4
https://www.youtube.com/watch?v=flvkYi753Js

Camel camel camel says this one is a great deal:


https://www.amazon.com/PowerFilm-F15-600-Foldable-Solar-Charger/dp/B002LCEQPU/ref=sr_1_6?ie=UTF8&qid=1486861423&sr=8-6&keywords=Powerfilm&tag=vglnk-c102-20


Only one left in stock.

It puts out 12 v with a cla output, so if you want USB you need one of these:

https://www.amazon.com/dp/B00VH84L5E?tag=vglnk-c102-20 USB car charger&tag=vglnk-c102-20



I wonder if they are closing these out because they have their new model which includes a battery (bad idea in my mind unless it is easily replaceable ).  Alternatively they may be changing their pricing structure as they have really priced themselves out of the market lately.