question

dov-aharonson avatar image

BMV-700 what am I missing

My system includes Multiplus charger inverter, CCGX , BMV700 , Shunt and the AGM batteries.

All equipment is Victron batteries are Lifeline AGM.

All equipment is connected on the "load" side of the shunt only the batteries are on the battery side.

When I shutdown the charger the BMV-700 and the CCGX show -4.5 Amp which to my understanding indicates that the batteries are being discharged.

BUT.....

When I turn on the Multiplus charger inverter it can for example show on the CCGX DC current of +30amp but the BMV-700 on the CCGX continue to show almost the same current around -4.5 amp.

While I expected it to show +25.5 amp.

It is clear that I am missing something since I know that the charger in fact charge the batteries and it is connected on the "load" side of the shunt.

In fact I think that the BMV-700 always shows minus values for current.

I appreciate help understanding this issue.


BMV Battery Monitor
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Post a photo of the shunt, and the batteries.
1 Answer
Kevin Windrem avatar image
Kevin Windrem answered ·

If you have any DC loads in your system, turn on "Has DC system" in the menus on the CCGX. This may help clarify where the power is going.

The Multi may briefly enter the bulk charge phase when turning on. If the batteries are near full charge (or fully charged), this should not last long and the current will diminish. But during this time the BMV should show a positive current. It isn't clear where the power is going or if the BMV is maybe broken.

A wiring diagram might help.

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Thank you for your feedback.

I am preparing a diagram but attached a clear photo of the shunt connection to the battery bank.

shunt-connection-1-l.jpg


The only connection to the batteries bank "minus" side is the shunt "battery" side.

The shunt load side is connected to a connection bar where I have the "Minus" of the Blue Solar MPPT 150|70 and the MultiPlus 12|3000|120 and the rest of the load connected.

The installation is on a boat (all Minus connections).

If needed I can put photos taken at the same time where the BMV-700 showing around -2A while the MultiPlus showing 40A while I shut down the MultiPlus the BMV-700 is showing around -4A. So while the MultiPlus is injecting +49A it is not reflected on the BMV-700.

I will add later a diagram but the connections to the batteries and shunt are clear and simple.

It is a boat so I even disconnected the AC shore power just to make sure it does not affect anything and it did not make any difference.

Any idea?

The PCB on the shunt has been flipped.

It might be an idea to remove the pcb and clean the shunt/pcb contact points, and reassemble tightly.