Hello again *g* have a question to the electric versed among you, have created a plan, can you switch it like that?? Red is Plus (cl.9), blue is mass (cl.3 and 13) My idea is to charge the car battery via the cable what’s on the car, with the charger installed in the caravan for the home battery. The charger should be able to switch from one to the other. Must add the cl. 9 at the 13pin socket on the car, does not come directly from the car battery ie, but comes at the driver’s side down in the footroom of kl.30 (that is in the car the bar with plus connection for consumers). Now I do not know whether from the 13pin. socket the current flows through to the battery, or whether the car battery has a blocking diode in the footroom???????????? Logically that the current from the battery goes into the footroom to the terminal 30. Logically also the second plus cable on the car battery goes to the magnet switch of the starter. The so-called ignition plus “D+” w as yes in the camping and car on Pin 10 is in the 13pin. Plug, goes also again to the car battery from the alternator, otherwise it would not charge the battery. But there we have it already, there must be lock or Schottky diodes installed in the car, because otherwise at the back of the car in the 13pin. plugs Kl. 9 and Kl. 10 have no connection, if one holds a pass tester to it (peepser)?????? that is still milking to the mouse …..argh ́ ́ ́ ;o) Dear greetings! EDIT: Oh so forgot, ha Be in the wowa, the plus cable which actually goes from the car to the Mika power supply completely agreed (blindly laid), because the living battery virtually replaces the car battery, that has the advantage that the car battery can never go empty, quite simply because it has nothing to do with the 12 volt supply in the wowa.