I'm talking about backpacking in the backcountry - no electrical outlets out there yet. Really, your suggestion doesn't make much sense even with electricity. I appreciate you trying to help though.
It doesn't require any electricity, the chargers I'm talking about are batteries. At home you connect them to electricity and charge them, in the wilderness (without access to electricity) you connect the battery charger to your phone with a USB cable and the battery charger charges your phone. Despite the charger being little more than a battery, the phone thinks it is connected to an electrical outlet.
The external battery charger I linked, with a 5200 mAh battery, should be large enough to top up the power on your phone twice without ever connecting it to an electrical outlet. And in terms of size, the charger/flashlight is roughly 3.75" long, 0.75" thick, and 1.6" wide, and weighs about 4 ounces -- so it is easy to carry with you. It also comes with a carrying case with room for the battery and a USB cable.