Grounding Cyrix and Battery Protect through the shunt?

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tunafish asked Jun 17, '19

Grounding Cyrix and Battery Protect through the shunt?

I am setting up my first install in my Volkswagen T5 van.

This is what I have right now (actually I still need to insert the Smart Battery Protect 65A)

I followed the manuals for the installs but now I was thinking... shouldn't ALL negatives pass the load side of the shunt?

How about connecting the 86 pin from the Cyrix and the GND pin from the SBP to the shunt? Would that make any difference? I guess both products will consume a minimum of power right?

One thing I noticed - and I think it is the Cyrix - is that my shunt measures +0.10A without any loads on! It is like the Started Battery is charging the Leisure Battery, even with the engine off, is this possible??

Battery Protect Grounding Cyrix Battery Combiner

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Answer 1 · 2019-06-18T12:31:47Z

wkirby answered · Jun 18, 2019 at 12:31 PM

Indeed, all loads AND charging sources should pass through the shunt otherwise that current cannot be measured.
According to your diagram, charge current from the alternator will not pass through the shunt.

The ONLY thing that should be connected to the Battery - side of the shunt is the battery - pole. You can then connect your ground strap and fuse box after the shunt.

If you see an offset of current flow when you know for certain that it should read 0A, you can zero this out via the menu option 09 (zero current calibration) on the BMV-702.

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tunafish commented · Jun 18, 2019 at 08:58 PM

Thanks for the reply!

How about this diagram?

Or should I connect the (-) from the Cyrix (pole 86) to the load side of the shunt as well?

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