Bavaria 36 2002
Because we have changed our engine and it has a much bigger alternator (115amps) we had to increase the size of the wiring to the batteries. We have therefore fitted a VSR(Voltage sensitive Relay between the engine and Domestic batteries. This has the advantage that you can get rid of the diode (which would have had to be bigger as well). You can use the thick starter cable to charge the starter battery and the only thick wires you need are the ones between the starter battery, VSR and Domestic battery. We tried a normal VSR to begin with and when it was engaged it got very very hot which must have been using current to keep itself engaged. We have since bought a Latch VSR from Stirling and this is working great. It only uses power when it switches on or switches off and doesn’t get hot.
The secondary advantage of the latch VSR is that if the solar panels get the domestic batteries up to 13.2 volts it joins the domestic batteries up to the starter battery and keeps that topped up too.