Moinsen, I have an understanding question about the operation of the 12V network in the trailer, which the SuFu could not answer. Please note: In my question it will not be about the 12V supply over the towing vehicle; that is not a topic and should not be included in the considerations. Also I do not want to buy a new electric block. Here the actual condition: caravan Knaus Azur, BJ 1991. As standard equipped with a 220V/12V converter. No battery. Some lamps and the water pumps run over 12V (so far from the converter supplied by land power). Some lamps, refrigerator and the Truma-Vent run over 220V. For the converter unfortunately, no technical data are available. The following is before: installation of a battery. Installation of a charger 220V/12V installation of a solar system. After the conversion – so I imagine that the 12V consumers should be supplied with the converter after the 12V has arrived. The 12V power supply is not supposed to be supplied by the 12V switch over the battery.