raymonddaf avatar image
raymonddaf asked

Victron Smart Shunt not showing charging current

I am looking for advice on wiring up a victron smart shunt to victron inverter as I am not getting + Current when the bus is started and batteries should be getting charged via the alternator (shows over 28v but the current shows as a minus for the draw from the inverter).

I think i may have wired something incorrect (possibly the bus starter batteries to the leisure batteries)

Attached is an image of how I have wired this up


BMV Battery MonitorSmartShunt
victron-wiring.jpg (97.0 KiB)
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2 Answers
Stefanie (Victron Energy Staff) avatar image
Stefanie (Victron Energy Staff) answered ·

Hi @raymonddaf,

wiring diagram looks ok to me, provided that it's exactly wired like in the diagram and the shunt battery side is on the battery negative.

I'm not sure about your question regarding the minus current. That's what I would expect to see when the inverter is switched on (regardless of the alternator current because that current is not measured through the shunt).

And I think you can't charge both battery banks at the same time with your alternator. You would at least need a charging diode, Cyrix -ct or a DC-DC charger in between.

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Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

Your mistake is the negative wire between starter batteries to the leisure batteries.
This wire must be connected to the "load/charger" side of the shunt.
Or remove this wire and connect the "load/charger" side of the shunt to the chassis.


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raymonddaf avatar image raymonddaf commented ·

Hi Matthias,

Cheers for the reply.

So just so im correct all i need to do is:

1. Remove the wire indicated (from neg starter to neg leisure batteries)

2. Ground the circled wire.

So this will still keep my leisure batteries as 24v (2 x 12v)?


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Matthias Lange - DE avatar image Matthias Lange - DE ♦ raymonddaf commented ·

You also could just move the wire from the neg of the leisure batteries to the other side of the shunt.


And as Stefanie mentioned you should install something into the positive wire. like a cyrix-ct or dcdc charger.
Otherwise the loads at the leisure batteries also drains the starter batteries.

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raymonddaf avatar image raymonddaf Matthias Lange - DE ♦ commented ·

Thanks, yes I will probably go with a dc-dc charger as i cant use a split relay as the bus is euro 5 so has a smart alternator which doesnt like the split relays.

Bus has 3 x 120a alternators fitted and my power draw is going to be quite big, somewhere in the region of 2500w so thats 104ah i would likely need a 120a dc-dc charger and the only one I have seen for a reasonable price is the sterling BBW12120 (although have been advised by a few folk that sterling inverters are not the best so now sure how their dc-dc chargers are)

Plan was to connect everything up and see the power draw then add the dc-dc charger and possibly increase the battery bank (bus will be running pretty much all the time as its a party bus and as its running the Alternator should put in more than it takes out but need to test it t ensure this is the case)

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