the overhead lights work on battery power, and have a place where a bunk fan/light can be plugged in. (like a headphones jack) does the light say what size jack it takes? are these holes universal in size? i have only found bunk lights with that style plug. what else works on that 12v outlet.? has anyone converted a usb charger cord to plug into that outlet.? i want to charge my devices INSIDE @ nite. does a ready-made exist? can i make one? i havea 12v extension cord (cigarette lighter type) with clamps to connect to battery i can use in the meantime.