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austin12 asked

Newbie B2B circuit breaker activating on engine shutdown


  • screenshot-20210521-114622.jpgHello. Rapido 2019 Moho ducatto I have a Victron non isolated smart 30 amp B2B charger.

I notice that the engine battery level reduces the same as the leisure batts. I presumed the engine battery would remain holding its charge whilst using the on board 12 volt leisure batts. (The original leisure cables had 2 heavy reds to the + on the leisure batts, (these are now on the + bus bar) do you reckon I should remove one of them red cables from my bus bar as I think it's going back to engine battery??? I have a Victron smart shunt on the negative side.. Everything goes through the bus bars not direct to battery as per instructions. So the charger shows bulk charging and gets warm with green blink it is charging.

Second question. I have a flick switch on off in the remote switch of the block at the left front bottom of the b2b If I leave the flick switch in the charger on position when I shut the engine off the volts on engine battery show like 6 volts (see second photo)and throws the 20amp circuit breaker that connects from engine battery to the b2b. Why is that? If I remember to throw the remote flick switch to off then turn engine off the breaker does not trip out.

Final question on the Smart shunt app screen which figure shows me the amps that is going into leisure batts? I expected to read like 40 amps going in with the onboard factory charger and the new 30amp B2B.

Sorry for so many questions but I'm new to this. Thanks


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MultiPlus Quattro Inverter Charger
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screenshot-20210521-114622.jpg (307.1 KiB)
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harold avatar image harold commented ·

Please make clear if your battery system is completely separated? Do you have a drawing?

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austin12 avatar image austin12 harold commented ·

Hello. It's a newish motorhome and I am sure the engine battery is connected to the leisure batts. Prior to me installing smart shunt and smart 30 amp btob there was 2 heavy red cables going to the positive on leisure battery. (These now go to the new positive busbar and one cable goes from busbar to +,on leisure battery. The shunt has all negative going through it and one cable back to the - on leisure battery. My gut feeling is that the split charger relay is stuck open and there batteries are now all connected, I fail to see how the engine battery van reduce exactly the same as the leisure batts. The dash switch for radio is off that feeds from engine.

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