When my wife and I bought our trailer last year. I noticed that it had 12 volt lights already added to it. What it didn't have was a converter! The previous owner ran all the wires under the dinette seat and had 2 deep cycle batterys wired in series with the 12 volt wires attached to one of the batterys. First thing I did was take the batterys out of the inside of the trailer. Next I went to our local RV store to find out how I could hook up the 12 volt system correctly, He was a great help! Next I got on Craigslist and kept my eye out for a converter out of a used trailer. I found one for $25.00. I then took it to my RV store and had them check it out to make sure it was working correctly. I then had to build a custom bracket to mount the battery to the tounge of my trailer. These older trailers have very little room for extras besides propane tanks. I ended up mounting it behind the tanks. I ran a positive and negative wire from the junction box to my battery, I also ran a positve & negative into the trailer under the Dinette. I then ran a positive & negative outside the battery box with a quick connection so I could run a trickle charger. The converter I bought did not come with a battery charger built into it. I then marked out a spot under the dinette to cut a hole to mount the converter.( The reason for mounting it there was because I had a 110 plug in that I could rob my electric side from and my 12 volt wires for all my lights were there.) I then ran all my 110 wires into the box on one side and my 12 volt wires on the other side. I also mounted a fuse block along side the converter for the 12 volt circuit. Wired everything up and WALA!! I now have 12 volt lights all working and when I am plugged in they all convert to 110ac!