For those of you that use a CPAP machine for sleeping like I do, I needed a way to power my unit from 12 volt battery while dry camping.. in our 3100RL I removed the front closet light fixture and added a length of 2 conductor wire (# 16 gauge is good) taking notice of which wire was the plus (positive 12 V), then ran the wire inside of the closet and down the side under the trim and out to my side of the bed to the CPAP unit with the proper plug for the CPAP.. perfect ! I reinstalled the light and all is good.. if anyone needs more details just contact me and I will be happy to elaborate.. another way is to use a small 12V inverter to power the unit with the 120 volt supplied power supply, but the inverters are power hogs and eat battery power fast so I try to stay away from them whenever possible.. Good luck.. happy camping. jerry