FNDC chronically reports faux SoC Decline during solar harvests

[StoneCove]

I’ve had this issue since I acquired a mis-parameterized installation on a home property I bought. I’ve put in the time to study the relevant documentation and have experimented/tweaked Mate3s parameters to attain what seems an optimal configuration (see right). Operation has been suitable now for a couple of seasons.

Still, the below happens all the time: though “From Battery” below is (graphically) a Solar pass-thru (in the large), SoC during harvests declines (steeply) kinda as though “From Battery” were not mostly a Solar pass-thru but instead a draw on Battery.

Anyone else having this condition, presently or past? Is there a remedy?

My reported Voltages are fine. Outback Tech Support (my thanks for their look-in and advice) suggests I just ignore my “unnecessary” FNDC SoC data — “You can stop displaying it on OPTICSre if it bothers you.”

Sure, but I’d much prefer a fairly sane SoC report than dismiss and ignore a problem read-out. (Doing the “ignore” rubs my “inner-engineer” fur exactly the wrong way.)

Thank you.

[raysun]

My initial suspicion is a shunt feeding the FNDC is miswired.
On the OpticsRE summary screen, click the Battery tile in the left menu bar. Post a screen shot of the Shunts graph.
Also, post a screen shot of the FNDC/Battery Charging parameters.

[StoneCove]

My initial suspicion is a shunt feeding the FNDC is miswired.
On the OpticsRE summary screen, click the Battery tile in the left menu bar. Post a screen shot of the Shunts graph.

If by
"OpticsRE summary screen"
and
"Shunts graph"
you mean OPTICSre DASHBOARD w/Battery button pressed, here is (bottom most):

Also, post a screen shot of the FNDC/Battery Charging parameters.

Here is:

[raysun]

The bottom "Battery" graph...
Slide the selector from "All" to "Shunt" and post the display for the same date as the ones above.

[StoneCove]

The bottom "Battery" graph...
Slide the selector from "All" to "Shunt" and post the display for the same date as the ones above.

Graphs I get for Shunt A, Shunt B, and Shunts A&B. [Shunt C is not in use.]

[raysun]

Shunt B, intended to track current flow between the FM80 and the battery, is seriously under-reporting, it would appear.
The shunts are precision resistors in which voltage drop is proportional to current, 0-50mV:0-500A.
A likely suspect is the sense wire between the shunt and the FNDC Shunt B port is loose or damaged.
A second suspect is the FNDC Shunt B port is damaged. Shunt C port could be tried.
Another possibility is the FM80 Bat (-) lead, or the Shunt B Battery (-) are connected incorrectly. The Shunt has two "ends" Battery and Load. The Shunt to Battery (-) cable should be connected to the Battery end. It should be the only cable connected to the Battery end. The FM80 Bat (-) to Shunt cable should be connected to the Load end of the shunt.
An unlikely suspect is the shunt itself is damaged. If the resistive component is shorted, it would pass current, but the sense terminals would not see the proportional voltage drop. If the sense terminals are open/shorted, the sense voltage would be likewise low.

CAUTION: Wiring panels contain lethal voltages. Use proper precautions when working in and around the power wiring.

If you open the DC wiring panel to inspect the shunt wiring, take and post pictures. IME, shunt wiring errors are easy to make, and sometimes hard to spot.

FNDC Documentation
FLEXnet DC Battery Monitor - Outback Power https://www.outbackpower.com/downloads/ ... _guide.pdf

Application Note - FLEXnet DC Programming & Guidelines https://www.outbackpower.com/downloads/ ... p_note.pdf

FN-DC Field Calibration - Outback Power https://www.outbackpower.com/downloads/ ... p_note.pdf

A typical graph of current flow in an off-grid system.
Notes:
The shunt labels can be edited via the Edit control on the graph screen.
It's not unusual for there to be minor "measurement leakage" in an enabled shunt port with no current flow. It typically shows as 0.01kWH/hour.

[StoneCove]

Thank you, raysun, for your analysis and advice.

[fcwlp]

To the right of your shunt A, B, C you will see an edit link. Click on it and give your shunts some real names.