Problem with smartshunt as DC energy meter

DIY
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1

My DC system is fed from a lynx distributor, and there is a smartshunt installed on the negative line from lynx to DC fuse panel. That smartshunt is configured as a “DC Energy meter” per the instructions in the smartshunt manual.

From the graph, you can see that ovenight (prior to sunrise) the smartshunt is recording 100% accurate data on my power consumption. I have a 12v fridge cycling, plus some small fans running. But once the sun rises, the power begins reading as negative, as if there is a source of charging coming from the DC system.

The only mppt’s charging, are wired directly to the lynx, so it is not possible that any of these mppt’s are charging via the DC system that the smartshunt is recording.

During sunlight hours (when the smartshunt is reading as if it is being charged from the DC system), I have put a clamp meter on the line that feeds the DC system, and the clamp meter confirms that the smartshunt and VRM displayed power is inaccurate, and that I am in fact discharging my same loads (fridge/fans) that the graph displays during non-sunlight hours.

You can see the very erratic reporting of DC power in the two videos, as if there is some calculation occuring? and even so, this erratic measure displays are not reported in the shunt graph as well. And then in victronconnect, it displays a constant negative (charging battery), which is different from what VRM remote console and dashboard are saying is happening as well.

I have tried configuring the smartshunt as a “DC system”, “Generic DC load”, “Fridge”, etc, and none of them have any change in behavior.

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Has anyone seen this happen before? I’m considering getting rid of the smartshunt, as it is even less accurate than letting VRM calculate what is going on with DC power by itself. Any help would be appreciated, thanks.

2

You have set it as DC Energy meter, what is the type of energy meter you have set it as. Are these the only DC loads, of so set it as DC System then the DC box on the GX device and VRM dashboard will display the current from the shunt. If you have chosen another category the DC loads reported on the GX device will still be a calculation subject to error.

3

I have been trying to figure this out for 2-3 weeks now, the majority of that time it has been configured as a “DC system” under “DC Energy Meter”, with the same result. I just changed it back to “DC System” now.

So perhaps when configured as a generic load, or other type of energy meter, that would explain the erratic VRM remote console reading in the video above.

But still when configured as “DC System”, it will report identical to that graph I posted, day after day.

Is there anything else I could check or adjust and try?

4

I can not think of anything else. Mine is set as DC System, it is connected to a Lynx Distributor and just has the DC loads on and works fine, nothing erratic, the DC box on the screen matches the loads I expect.

5

I am nearing end of the sunlight for the day, so I will post another graph tomorrow morning along with pictures of wiring/clamp meter and see if the behavior continues. Thanks for your response thus far, I appreciate your time.