Keep your cell on your body. You may not have the chance or ability to go back for it.
I'd also keep the chargers. I have plug in, 12v and AA battery powered chargers in my kit. But, I'd suggest trying to make the system as generic and interchangeable as possible. All mine are USB based, and I carry a very short micro and mini USB cable.
I'd love to add a decent portable solar panel to this mix, but haven't managed to yet as the decent ones appear a bit bulky and expensive.
John -
In case you've not seen it, happen to run across the newish
Brunton Restore solar charger. Fairly small at 3" x 5.75" x 1.13" and price-wise not too bad ... retail $125 but <$70 at some on-line retailers.
Fairly good reviews of those I've read. One of those on Amazon the exception. But who, except those of us in the desert, routinely encounter 105°F temps. May have been an anomaly since Brunton-rated up to 120°F.
Amazon reviews,
Practical Travel Gear review and
Woods Monkey review. Greatest failing -- but, of course, not insurmountable -- seems to be compatible connectors.