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CB_Midkiff avatar image

Shunt install question (BMV 702

I have two battery banks, a housebank and starter battery that are monitored by an old(and falling apart) battery monitor.

My new monitor is a Victron BMV 702).

My question is. Can I just jump off the old shunt to the new and plug the monitoring cable in the new shunt? Leaving all the original wiring in place.

Attached is a crude drawing to illustrate.


BMV Battery Monitorinstallation
wiring-diagram.png (22.1 KiB)
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10 Answers
WKirby avatar image

Hello David
Not sure why you wouldn't be able to post your own question. Anyway, not to worry.

I drew a crude diagram. I hope it answers your question.


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david avatar image

thank you very much

great

that is the bank I have as house bank,

now if I want to use the "midpoint" option I suppose will have to break the bank on two? house banks with 2 batteries on each?

David


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david avatar image

Suspected that

I want to thank you again for your time and patience.

On another issue need to figure out to post directly,must be a guide on how to post,I get in trouble at the end with tag and space. and by not filling those two windows properly keeps rejecting my post.

Is a generation gap

thanks David

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WKirby avatar image

If you are using 12V batteries in a 12V configuration then you can't measure the 6V mid point.

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david avatar image

also if I could be directed to the right forum?

thanks

David

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david avatar image

I am a new user trying to post a question and the question typed fails to go thru,I know is not appropriate to interject here but have found no other way,cannot find an administrator to the forum to seek help,sorry.

question trying to post

Just received my new bmv 702,included instructions and diagram for 24 and 48 volts.

My bank is four 12 volts batteries connected in parallel,is there a diagram that shows how to install it?

again apologize

David



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Rossland avatar image

I had the same "problem". I installed a 702 because my old battery monitor was not very accurate, but I had to leave the old BM connected because it sent data to my battery charger. So I replaced the old shunt with the Victron shunt, and connected both the 702 and the old BM to the Victron shunt. The 702 works great, and the old BM is still not accurate, but no worse than before.

Rick

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Bluepowershop avatar image

A shunt has two sides, a battery side and a system side, it is possible that your old shunt has multiple connections on both sides but it stays a unit with only two sides.
When i look at your scheme (disregarding the new shunt) it is correct.
The reason that your starter-battery's minus is connected to the (load&charger) system side because this is your systems negative side.
Just undo the present (house) battery minus from your old shunt and connect it to the "battery only" side of the Victron shunt.
All other wires go to the "load and charger side", it is as simple as that!

Regards

Mark

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CB_Midkiff avatar image

@Peter Polz The reason I have that starter battery connected like it is, it because that is how Victron recommends a second battery be connected to their shunt. It does'nt make any sense to me either. But I'm not an electrician. :)


The reason for asking this question and not just replacing the existing shunt is because it is....odd. It has 4 terminals and I cannot figure out how I would get them all to connect to this one tiny Victron shunt. The old one does not have a PCB.

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The 702 just make it possible te messure the Starterbatterie Voltage in that way but you don't monitor the SOC of both.

As written. If you really can't replace the old one, you have to remove the PCB from the new Shunt and add it to the old shunt. I am sure it doesn't fix out of the box, so you have to find a solution by yourself how to connect the 2 contacts for the measurement to it

Peter Polz avatar image

I cannot see your concept of monitoring both?. In case of old System you just monitor only current of Housebank.. for that you have to simple replace the existing shunt with the new one.

A second parallel shunt will result in half resistance, that can be adapted in BMV Config but you also get an uncalculatable 3rd resitance in cabeling between shunt that will cause measurement errors, so that solutions doesn't works for me. => Changing existing shunt will be my only recommendation


Additional Info: One thing which will definitly work is to connect only PCB of the new Shunt(without shunt) to old shunt.

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