I want to install an Orion DC-DC Smart 12/12/30 in my van. It would be connected to the starter battery under the driver's seat all the way to the back of the van on the opposite side (passenger side). My question is, if I run the wiring up to the ceiling, to the back, and back down, the distance would be 10m one way (2m up, 4m to the back, 2m across, 2m down), if I run it through the floor the distance would be around 6m one way (4m to the back, 2m across). Keeping in mind derating factors (running continuously for more than 20m, being in a conduit or insulation), I've calculated I need a 0awg wire (50mm), which seems way too big. I don't know if my calculations are wrong? Victron recommends a minimum cable gauge of 16mm for a 5m distance (i'm guessing this would be one way?).
I'd appreciate any help!! Thank you