Grounding question

[ermracing]

In our bus we have house batteries (4x230ah, 12v) with 3 solar panels feeding them, then our pure sine wave inverter charger going to a 110v breaker box feeding 4 circuits. The batteries also feed a 12v dist panel. All the grounds for the 110v circuits and 12v from these batteries come back to the batteries so it is isolated from the bus.

We are thinking of using the alternator as a source for charging the house batteries, but realize this would require grounding them to the bus, at least while they are being charged.

Does this pose any particular problem? Could we use an isolator/cut-off switch to connect and disconnect both the POS and NEG to the house batteries so they are only grounded to the bus while charging?

[Johnny Mullet]

My entire system is grounded to the bus chassis.

[john61ct]

First off, "ground" by itself is ambiguous, implies PE protective earth.

Negative return for all DC circuits should be at the same reference potential, aka "common reference".

This is always done via connecting ("bonding") the negatives to common **chassis** reference points aka "chassis ground" at several points including of course the main frame and engine block.

AC circuits should **not** be bonded to these references, and when connected to shore power, bonding to PE should be **only** at that one single point. Get a professional to sign off on those circuits.