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ur12vman asked

Autostart misbehaving, Cerbo GX starting generator early

Cerbo GX with BMV712. Several times in the last week the cerbo has activated the gen start relay before the battery SOC gets down to the set point. I have SOC start enabled to go at 40% and stop at 95%. There are no other conditions set for autostart. Occasionally the system will close the relay at somewhere around 85% and run to 95%. In the menu under gen start, the readout states "running from SOC" I do not have "quiet hours" set to on. The SOC on the BMV readout agrees with the Cerbo readout. I cannot understand why it comes on before getting to 40%. Any ideas? Cerbo set to auto update, firmware is 2.58.

cerbo gxGenerator
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Mark avatar image Mark ♦♦ commented ·

Yes that's odd, is the 'periodic run' condition also off?

And can you check under 'System setup' > 'Battery monitor' to confirm that the BMV is selected as the battery monitor?

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ur12vman avatar image ur12vman Mark ♦♦ commented ·

Yes to all of that.

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3 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Is the system connected to VRM?

There is a slightly hidden feature in the advanced XLS/CSV export download that shows the reason for the generator start.

Could you check that?

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ur12vman avatar image ur12vman commented ·

Yes, its on VRM, how do I find that data?

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ur12vman avatar image ur12vman ur12vman commented ·

one such incident happened at 8-18 at about 1700, I can see on the VRM SOC chart where the SOC went from around 80% to 95% in a steep incline which separates a solar charge from gen charge. Solar charge is a much less steep slope at 1.5kw-2kw charge vs the gen at 9kw charge.

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1598117187713.png (220.9 KiB)
ur12vman avatar image ur12vman commented ·

I found the download data link and after setting the date/time parameters downloaded the xls for that time period, the SOC is at 80.9% and it read running from State of Charge. So it actually believes that it started by SOC even though it was not at 40% yet. I can email you the download if you want to see it. I'm thinking I found a bug.

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ur12vman answered ·

Some additional sleuth work with help from Guy Stewart allowed me to find this bit of evidence.

There is a download from cloud link at the top right corner of the advanced page on VRM. Setting your date/time parameters allows a very comprehensive data dump for that time period. Try a one day download and see the huge number of data points you get.

At 1707:00 on 8-18 the system went from 87.5% SOC to 1.2% for about a second and then to 87.1%. this one second blip was enough to close the relay and start the genset which ran for 16 minutes until it reached 95% at which point it stopped.

Now to figure out why the SOC went to 1.2% for one second.

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ commented ·

It could be the VE.direct connection to the BMV is not 100%?


Try removing ve direct cable and seeing if it effects the SOC. If removing the cable causes the SOC to change, then the connect might be leading to the issues you are seeing.

Can you try changing the battery monitor selected from automatic to BMV in the system settings menu of the GX - might not help, but it might.

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ur12vman avatar image ur12vman Guy Stewart (Victron Community Manager) ♦♦ commented ·

I'll check that but it should be a good tight fit. It happened again today. The two units are 18" away so the cable is secure. I'll make the change in the menu and get back.

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ur12vman avatar image ur12vman Guy Stewart (Victron Community Manager) ♦♦ commented ·

OK, I made the menu changes to use BMV instead of Automatic selection. I also momentarily disconnected the BMV VE Direct cable and that did not trigger the gen start. I looked at the data from the last un-intended autostart and the SOC is at 0% for that one second, it was at 83.9% before and 83.8% right after.

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1598743101609.png (122.8 KiB)
alex-solar avatar image
alex-solar answered ·

We got same problem in a system where we have:

1. Victron Quattro 48/15000/200 - 6 pcs.

2. Victron SmartSolar MPPT VE.Can 250/100 - 8 pcs.

3. Victron Cerbo GX + GX Touch 50

4. BMZ ESS 9.0 - 9 pcs.

5. Fronius Symo 10.0-3-M - 1 pc.

But after downloading the log file we saw that with SOC everything was ok.screenshot-1.png

Everytime when system goes to inverting the generator starts immediately. What could be the problem?


screenshot-1.png (66.1 KiB)
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