Over the last few trips with my trailer I discovered that in the high-tech camping world I need to make some improvements to my 12 volt power system. The trailer has one 12 volt power plug in the panel below the couch. When my dog travels with me, which is almost all the time, he renders this outlet unusable much of the time because he sleeps with his back against the panel which blocks access to the power port. I have been charging my tablet and phone many nights by plugging them into the Jeep power ports. This not ideal as it could drain the Jeep's starting battery and should cellular service be available at the campsite it makes it impossible to use the phone quickly in an emergency. Also after several nights of running lights and the heater I was wishing for a way to monitor the battery voltage.
It had been over a year since I had removed the small cabinet and checked up on the battery. It seemed a good time to do a little improvement while it was out. The battery appears to be ridding fine with no movement or corrosion of the terminals. This is the voltmeter and power supply ports I installed in the cabinet. There wasn't room to install them with the face plate.
The trailer had not been used in about five months ( I know that's bad) and the battery was at about a 50% charge level. Because the 12 volt system is controlled with a battery shutoff switch which leaves only the vehicle charge line connected to the battery. I decided the best way to attach my trickle charger to the trailer would be to use a vehicle trailer socket and wire a charger pigtail to it. Now I can charge the trailer battery without opening the top to activate the 12 volt system by plugging the trailer light cord into the adapter and the adapter into the charger.