Victron BMV 712 Install

[Letterkenny]

Could someone provide some tips on how I should install this Victron BMV 712 based on the attached diagram of my electrical setup? Any specific gauge wires or just what is used with the battery? Unless I’m missing something I’m finding the mainly photo diagram installation confusing.

[CharlieJ]

The B- from the batteries are connected to the 712 shunt at the connection marked "Battery Only" and the B- from all sources and loads are connected to the connection point marked "Load and Charger".

It is best practice to route all of the battery B-'s to a bus bar and then use a short conductor of appropriate size between the bus bar and the "Battery Only" connection point on the shunt. Similarly, connect all of the source and load B-'s to a bus bar and connect that bus bar to the "Load and Charger" connection point on the shunt.

[Dsanduril]

Based on the diagram you may be in a bit of a pickle. What are you trying to monitor with the B!V 712? The house bank? BA1 + BA2?

In that case normally you would install the shunt in the black cable from the negative switch to BA1, but in your case (at least according to the drawing) that also carries all the current for BM (the starter battery?) and so wouldn’t monitor just the BA batteries.

What is the box above the batteries/behind the engine with cables from both battery switches? If not a load then it looks like two “house” negatives from electric winch and AG come together at the negative switch, those could be connected to one end of shunt with a short jumper from battery end of shunt to the switch.

[Letterkenny]

I’m probably overly simplifying this but would I not just wire the last negative battery connection to the shunt (buy new cable of same gauge) and then take the existing negative going to the battery terminal switch and wire it to the load side of the shunt. From the positive side, I would just connect this to the first of the batteries in the house bank series and it would get the usage between both since they are in series. Is this right?

[Dsanduril]

The batteries shown in your diagram are in parallel (negative connected to negative) not series (negative connected to positive). But kind of immaterial.

The shunt measures the current in the negative leg. The positive connection is used to measure the voltage (but has nothing to do with measuring the current) and to power the electronics.

If you connect the shunt in the single negative cable from the switch to the batteries (if the drawing is correct) it will measure the current in BA1, BA2, and BM. If that’s what you want then all good, but if your are trying to monitor just BA1 and BA2 then it won’t. In that case you need a negative wire that just goes to BA1 and BA2. One option might be to disconnect the negative from BA2 to BM and then run a new negative cable from BM in parallel to the switch. That would be electrically the same but would separate the negative currents so you can use the shunt on the BA batteries alone. If that’s what you are trying to accomplish. And if that is physically feasible.

Another option would be to connect the existing main negative to the shunt and, at the same end, connect a jumper to BM. Disconnect the jumper between BM and BA2 at the BM end and connect that to the other end of the shunt (so it runs from the battery side of the shunt to BA2).

All of these suggestions depend on what you are trying to monitor and actual physical layout.

[smac999]

Remove ba2 black cable. Cut black ba1 cable. Insert 2 new lugs and shunt into ba1 cable where cut. Create new cable from start battery to load side of shunt. Ba2 cable may be long enough to reuse if shunt is near battery.

The shunt only goes on the 2 house batteries.

[Letterkenny]

Thanks for the help. See attached for a photo of the batter box.

[smac999]

Looks like the diagram was wrong and the banks already have their own ground wire feeds which is good . So you just need to intercept the hiuse neg wire.

[Letterkenny]

Originally Posted by smac999

Looks like the diagram was wrong and the banks already have their own ground wire feeds which is good . So you just need to intercept the hiuse neg wire.

Essentially wire the last negative from the house bank to the shunt and move the wire that was going to the bus bar to the load part of the shunt? Do I need to move the starting bank to the terminal directly if I want to monitor just house?

[Zzmeyer]

Smac999 is correct. The Jeanneau 349 used to be wired with common negative across both house and starter, hence the diagram, but the later deliveries have them separate. The shunt will be attached to the top right negative stud in this picture.

[sailcrazy]

following.