Hi Nigel,
It doesn't help in these matters when you weren't told by the previous owner how they all work together! On my auxilliary control panel I have a 3-way switch. Car-Off-Aux. I had taken it that this was controlling where the solar charge was being directed, so normally have it in the off position, except when the van is being used and the fridge is on. In the off position the extra room lights and the water pump are also off. Apparently there is also a Victron controller somewhere, but not yet found, that could affect what is being charged. I have now been told that it would be best for the 3-way to be in the Aux position so that the leisure battery is being charged at all times. Just concerned about what overcharge cutout is in place if I do.