Just spent two weeks hunting, which was to be a test for the oem dual battery system and my own requirements. since i posted my build
here, ive gone on to add an engel 40L fridge and a cheap 80w renogy solar panel. I wired 12awg solar cables (via a 20a fuse) to my roof rack through the external roof connections at the front right (pull the handle off, pop the electrical cover off and snake wires through the rubber gasket to reach on the inside by pulling off a couple interior push plugs from the ceiling, and sneak down the inside of the door seal to the battery compartment). For good mesure i put a renogy 500a shunt onto the secondary battery; my reasoning was that the electrons from the solar panel to the D250SE would be directed to the secondary battery, then trickle back to the primary battery via the smartpass when the secondary was fully charged. had both batteries on a trickle charger before leaving. The secondary never did better than 56% SOC according to the shunt. Odd but didnt think much of it. Out in the wild i would have primary battery SOC 70-80% by 530 AM most days (in the tents by 2100 most nights) which seems appropriate for the draw of the fridge and light use the night before. This is as per Ineos SOC monitor visible under the offroad headings. My renogy monitor showed a gradual decline in SOC of secondary battery, so that by day 12 it was reading 16%, and never seemed to charge during the day despite the miles. the smartpass and d250se never registered a fault and seemed to indicate appropriate charging function according to their lights. I did notice on one hot sunny day that the primary battery had charged by 10% while we were out walking. Im not sure what to make of it all, but dont like that i cant puzzle out or monitor my batteries better. I think i will be switching to a more conventional system, and powering everthing off the secondary battery (or batteries if the black friday sales are good).
