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Rather than run an additional large gauge cable from the Multiplus chassis terminal back to the system negative bus, or to a grounding bus that is also connected to the negative bus (which is connected to the vehicle chassis), why not just run a large gauge "jumper" from the Multiiplus chassis terminal to the second negative terminal connection point found on the Multiplus 3000?
Why isn't this done? Or if its done (and fine to do), why don't people talk about it?
If you are asking why not use the chassis for the inverter DC cabling, the answer is the amount of current in these cables is very high and not at all constant. The inverter (or charger) imposes a current variation (aka "ripple") at twice the AC frequency (100 Hz for 50 Hz systems and 120 Hz for 60 Hz systems). This variation is substantial. Both the DC and AC components of the current from the battery needs it's own path to avoid upsetting other components in the system.
A similar direct path to the battery exists for a vehicle's starter motor for similar reasons.
It's also common practice in RVs, to not use the chassis for DC return paths. Each branch circuit is typically returned to the distribution panel separately just like is always done for AC circuits (hot + neutral). This keeps each path "clean" and avoids upsetting ground potentials through out the RV.
No, I’m not talking about the vehicle chassis. I’m talking about connecting the multiplus chassis terminal to the negative terminal, which is ultimately connected to the system negative bus, and then vehicle chassis. Doing that vice running a separate conductor from the multiplus chassis to the vehicle chassis. (Edited original post to clarify this).
