An RV Converter is a switching power supply, that converts 120 volts AC, to 12 volts DC, for running 12 volt lights and 12 volt appliances. They are also battery chargers.

This particular converter, had some issues. It wouldn't run the lights, or the appliances, and it didn't charge the battery, at least not up to the level it should have been.

The two large white things on the right, are ceramic resistors, and are designed to dissipate a lot of heat. The problem, as I see it, they are mounted right on the pc board, and they get as hot as blazes! I temporarly raised them off the board. If you look at the board, it is burned badly, from the heat. The electrolytic capacitor next to the resistors, not surprisingly, failed, along with 6 others on the controller/charger board.

I located (and replaced) all 7 failed caps, with my esr tester. I rearranged the resistors, and mounted them on a little bracket, epoxed to the board (not shown). A small fan was mounted, continuously blowing air through the resistors.

This is what the converter looks like out of its case.

I drew a schematic, as best I could, of the converter, but it does not include the small switching supply controller/charger combo board.

Click to see schematic

This converter has a '3 stage smart charger', which is the type of charger that should be used to charge deep cycle batteries. In order for the charger to work properly, it needs to read the voltage of the battery accurately. If the charger is at one end of the rv, and the battery is at the other end, it is unlikely to get an accurate reading, if the wire size is too small, or there are poor electrical connections along the way. If there is any voltage drop in the wire, the battery will not receive a full charge, and the life of the battery will suffer.

This is my esr meter. A description can be found elsewhere on the site.