Circuit Length

[Jet]

To determine the wire gage I need I first need to determine circuit length. Is the starter battery to dc-dc charger to BMS to battery to fuse box to appliance/load one big circuit? Are they separate circuits? Thanks

 

[John Frum]

To determine the wire gage I need I first need to determine circuit length. Is the starter battery to dc-dc charger to BMS to battery to fuse box to appliance/load one big circuit? Are they separate circuits? Thanks

For an dc2dc charger you have 2 circuits.
input circuit: starter battery to dc2dc charger and back.
output circuit: dc2dc charger to house battery and back.

 

[HRTKD]

If you think of it as one big circuit, you'll end up with much larger cable than if you thought of it as circuit segments. Bigger cable isn't necessarily a bad thing, but it is expensive and harder to install. The segments are what you should be going off of and depending on which wire gauge calculator you're using, you have to use the round trip distance, not the one-way distance.