Hi. In our 1st van I ran a simple Voltage Sensitive Relay via an overload to the back of 2 different tow vehicles and utilised 2 of the heavier 5 pins of a 12 pin trailer plug to Feed the van battery. It worked better than no charging at all but I suspect of fairly ordinary performance.
In the latest van (2014 build) the charging system is a Setec D250S which is both a solar charger plus a DC-DC charger of 20 amp capacity. I have had it tested (Bill’s Bus Stop - Tauranga) on a fine day and it was poking out the full rated 20 amps from solar panels and the same with blankets over the panels and the motor running on the Cruiser. It is performing similarly on the Colorado. Both vehicles have had VSR plus Overloads fitted adjacent to the tug batteries and 12 pin trailer plugs. I am quite satisfied with the performance of this regulator but fully aware that it is limited to wet-cell or AGM batteries and max charging rate of 20 amps. With my 200 a/h of AGM and 450 watt of solar this is fine for me. We do not suffer from power anxiety even though we very rarely run on mains power. Cheers.
Derb. 2017 Colorado LTZ 4 x 4 Auto. 2014 Southern Star 720 and 1980 Zephette 340. 2 x 100 a/h AGM. 3 x 150w solar. Ctek D250S-Dual controller/MXS15 charger.172L fresh/grey. Diesel heat. RMD8555 fridge.