Sooo... you got some villagers with nothing but a 12V battery (no real 'lectricity). Have you seriously thought about this? Why I say that is as follows. Yesterday I was out camping and brought the outernet dreamcatcher setup (after ginning up my previously shown platform and antenna mount for gorilla tripod. I used a Samsung adaptive fast charger. Here are my results:
1: Plug into cig. lighter outlet, car off: Board blinks, runs for 30 seconds, shuts off
2: Plug into cig. lighter outlet, car on: Board runs
3: Plug into cig. lighter outlet, start with car on, leave 30 seconds, shut car off - board runs.
4: Add 6' USB extension to setup, try scenarios 1-3. Board blinks, runs for 30 seconds, shuts off.
So there is a marginal voltage condition. The Samsung adaptive fast charger is spec'ed for 2 amps. This might be marginal. Even with car on and adding a bit of overhead Voltage, that extra vew mllivolts might get droppped down again in the 6' USB.
5: My 120V usb Samsung adaptive fast charger. Works fine, last a long time. Didn't try with extension yet...
Soooo... what 12V usb charger is KNOWN TO WORK WITH CAR OFF AND BATTERY FULLY CHARGED (I think 12.6 v is average good charge for a normal battery). OUTERNET should already loooonng ago have answered this.