question

Yes it sounds like it may be faulty...

But are you sure that you have no 'load' connected & turned on at the same time?

Have you also tried physically disconnecting any 'load' cables to be 100% sure? (so that there is literally nothing connected to load/charger side of the shunt)

It would also be beneficial if you could take a photo of the install (specifically the shunt & wiring to/from it - also how you have wired your 2x batteries) & post it here for us to review/check.

Maybe also check the screws that secure the circuit board to the shunt end blocks are both tight.

Hi Mark,

Thank you for your answer.

The only load I can have are my solar panels (disconnected from the MPPT) and the engine alternator (stopped).

Here is some pictures of my install:

On the third photo you can see that's no current at all measured, but my BMV still shows 18,6A...

Is my controler faulty or did I do something wrong?

Hi Vennec,

There is a fair bit going on with your wiring & based off the photos alone it's difficult to see / fully understand what's running where.

In saying that, the basic wiring to make the shunt / BMV read correctly all looks fine.

Since you have tried physically removing ALL connections from the 'load/charger' side of the shunt (as a test) and also verified with a current clamp I think it well proves that something is up with the either the shunt / circuit board, the UTP cable or the BMV.

So if you take it back, to be safe make sure you exchange the lot.

Also, to me a ~18A reading out of the box (before calibration), seems too high for a 'real' no load/charge condition, so it may be out of range for the 'zero calibration' to correct this. I don't know...

On a slightly separate topic, I think that I can see the main pos & neg cables both connected to the SAME battery. If I see correct, then it would benefit the battery life if you swap either main cable over to the other battery. This will ensure a better balance between the 2 batteries, as at the moment the battery with both cables directly connected would be doing slightly more work & also taking more charge.

Hi Mark,

you are wright when talking about a fautly UTP cable.

It might be the source of the problem.

When I wiggle it, the BMV shows current moving from 15 to 25A (with still no charge!)

I'll make a test with a new UTP RJ12 cable soon.

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Nice work! It seems like your having some fun diagnosing the issue.

Are you able to isolate the issue to a section within the cable or to one of the plugs/connections?

If it's at one of the plugs / connections then it's most probably a poor electrical connection between one of the terminals in the plug & the wire. During crimping the terminal is pushed into / through the wire insulation to make contact with the wire.

Possibly you could try using a small flat screwdriver to ensure each terminal is fully pushed into the plug housing & wire (unless you have a suitable crimper handy).

Also look into the trasparent / clear plug housing to see if there is any obvious issue with one of the wire / terminal interfaces (like a single or multiple wires being too short / not fully inserted into the plug housing before crimping).

You could also do a continuity check for each core with a multimeter, but there is still a risk that it might read 'good' due to the pressure from the multimeter probes possibly temporarily resolving the issue - still worth a try to pin point the exact core with the issue.

Also inspect the spring terminals in the mating socket on the BMV or circuit board to ensure that there are no bent / damaged spring terminals.

If you are replacing the cable make sure you use an appropriate replacement - not a phone cable.

You or someone else could also crimp a new RJ12 plug on the existing cable. I did this to mine to shorten it from the original 10m length provided.

Thank you Mark for you accurate and detailed answer.

I can't shorten the RJ12 cable myself, I don't have the plug and the special tool to do it.

(It seems Victron is the only one to use RJ12 cables...I have all the RJ11 and RJ45 stuff at work)

The seller (MyShopSolaire - very good indeed) is shipping a new RJ12 5 metres cable (the good length for my installation)

I'll test the BMV and shunt sockets before I get it.

Well noticed in your previous post when advised me to modify the batteries wiring.

I'll do that as well.

As soon as I turned all power off and saw 18Ah, I would have declared the unit defective and replaced! I admire your patients.

I had a similar problem with my BMV712. All data are good except the charge intensity which gets wrong when the charge exceeds 14A. Even if the charge gets to 30A the BMV still shows 14A.

I tried a new 10m cable and it was worst. I shortened the original cable to 7,5m and it was better. I shortened it again to ~4m and it was good !

Thank you, without this thread, I'd never thought the problem would come from the data cable.