question

ramack avatar image
ramack asked

Multiplus 2 not inverting (OFF/Passthru) while grid connected

I have a Greenrock system from the insolvent Austrian supplier Bluesky with LTO batteries (Carbocab). As they "forgot" to add a proper BMS with balancing to the batteries I added it myself and have it connected via RS485 using the Beaglebone running VenusOS. I got rid of the Smart1 EMS and the BMS was included, as it did only monitor the complete stack.

Running 4 batteries in parallel I wanted to connect the remaining 3 and aggregate the batteries on dbus for controlling everything.

I cannot reconstruct the exact steps, but I ended up with a Multiplus showing state Off in VRM:

1686774099767.png

The ET340 grid meter is working fine (from what I see) and the BMS is also showing good values with 1 second update rate:

1686774192444.png

As soon as grid fails (or I switch it off) the Multiplus starts inverting supplies the critical loads from batteries but stops after the relay tests and wait time after grid is back.

Interesting is that in the VRM online portal I see the grid meter as N/A, while the AC-loads are getting their power values from the grid meter:

1686774623558.png

In System Settings I have chosen the MP2-internal Battery Monitor to be used, but also with the serial BMS it shows the same behavior.

I tried

  • VenusOS 3.0 and 3.10~8
  • Multiplus Firmware 485 and 502
  • Fresh installation of the VenusOS
  • With and w/o serial BMS connected
  • I checked several similar questions and the FAQ 4:

Q4.1:grid meter connected, and reporting data in ~1 Hz, also with ESS/Grid meter = Inverter/Charger I have the same

Q4.2: my BMS is not CAN-connected but RS485, as it is in VenusOS probably the same I checked that I have regular update, by setting the System setting/BatteryMonitor to the serial one I also see the SOC in the overview, so I guess the first picture above is only due to the off state of the MP2 - even though the SOC of the MP2 battery monitor is showing in the online VRM portal.

Q4.3:

N/780473368955/battery/4/Info/MaxDischargeCurrent {"value": 35.0}
N/780473368955/battery/4/Info/MaxChargeCurrent {"value": 8.0} N/780473368955/battery/4/Alarms/HighChargeCurrent {"value": 0} N/780473368955/battery/4/Alarms/HighDischargeCurrent {"value": 0} N/780473368955/battery/0/Alarms/HighChargeCurrent {"value": 0} N/780473368955/battery/0/Alarms/HighDischargeCurrent {"value": 0} N/780473368955/battery/0/Info/MaxChargeCurrent {"value": 8.0} N/780473368955/battery/0/Info/MaxDischargeCurrent {"value": 35.0} N/780473368955/system/0/Control/MaxChargeCurrent {"value": true} N/780473368955/system/0/Control/SolarChargeCurrent {"value": 1} N/780473368955/vebus/288/BatteryOperationalLimits/MaxChargeCurrent {"value": null} N/780473368955/vebus/288/BatteryOperationalLimits/MaxDischargeCurrent {"value": null} N/780473368955/vebus/288/Dc/0/MaxChargeCurrent {"value": 35.0} N/780473368955/settings/0/Settings/SystemSetup/MaxChargeCurrent {"value": -1}

Q4.4: Don't see any reason for discharge disallowed.

Q4.5: I did not change any grid code settings (don't have the password, it's Germany) and have the AUX in open (I guess - never touched it)

Q4.6: no change in Mains wiring and it worked perfectly for months. In VEConfigure I did not see any suspicous error in the IP (NS) protection log on the grid code page.


Other settings that might be important:

- ESS assistant active in VEConfigure

7.png

- ESS config in Venus:

screenshot-2023-06-14-at-22-57-23-remote-console-o.png

screenshot-2023-06-14-at-22-58-15-remote-console-o.png


And now I am out of ideas, how I could get the Mutliplus2 again into the state to regulate to the grid setpoint and would appreciate any idea of what I could try or show to solve the issue.

Thanks in avdance.

Rapha

Multiplus-IIESS
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5 Answers
ramack avatar image
ramack answered ·

Now I came up with a completely fresh installation of VenusOS on another beaglebone, and guess what: everything is back to normal. - I didn't recognize the root cause in the diff, but I am quite sure it was something in the /data partition that was kept on the reinstall of VenusOS earlier.

So in case you have similar trouble, backup your /data an wipe it. (maybe VenusOS needs to be fixed/reinstalled afterwards)

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ramack avatar image
ramack answered ·

Nobody not even an idea how I could search for the reason why the Multiplus 2 is shown as off in VRM and passthru in the online portal graph beside the FAQ? Or maybe some advice how I could dig deeper into those questions?

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sharpener avatar image
sharpener answered ·

Have you knocked the physical three postion switch underneath the Multi? It is easy to do by accident.

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ramack avatar image ramack commented ·
That would be a good explanation, but I checked it. The switch is in position '1'. Otherwise the MP should not start inverting on grid failure, should it?
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ramack avatar image
ramack answered ·

In the meantime I went through all fields in dbus-spy and didn't see suspecious values that could explain the behaviour and also tried a full reset without grid and battery supply on the Multi. Downgrading the MP2 Firmware and also the ESS assistant did not help and I have still: mode passthru when grid connected. I am about to believe that there is another bug as fixed some in the recent firmware versions.

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matt1309 avatar image
matt1309 answered ·

Hi @ramack

My guesses (probably not the answer)

Is the voltage is fine on AC side of multiplus ie to confirm 100% no issues with incoming grid.

My other guess is maybe the ET340 setup. Has it been configured as a grid meter?

Settings -> ET340 -> setup -> Role -> grid meter.

Also does it show up under device on VRM page?

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ramack avatar image ramack commented ·

AC voltage (Multimeter and also the VEConfigure shows it ok) and grid meter seem fine updating with ~ 1Hz, showing up in the device list.

Even without grid (and without grid meter connected and change the ESS config to use the inverter) - while the Multi is inverting I see the Multi in state OFF in the GUI:

screenshot-2023-06-20-at-20-19-42-remote-console-o.png


For me it really feels like the Bug that is described (in several versions) in the release notes:

It proved that (in rare cases) with firmwares xxxxXX the Multi could get ‘stuck’ in the off state.
It could not be switched on anymore neither locally nor remote. Even power cycling the system does not fix the issue.

(note that communication with such a unit is still possible).


Does anyone have an idea how these bugs could be identified? What can I do to prove that I have (not) the same issue? (Yes, I had run 505 firmware before, nur running 485, but will now retry it with latest Multi Firmware, maybe without the ESS assistant.)

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ramack avatar image ramack ramack commented ·

upgrade to firmware version 505 doesn't change the behavior with ESS assistant, but after the upgrade in default configuration I have seen (before adding the ESS assistant) that the charger mode of the Multi was active and it was also inverting on grid failure. So I would say that this brought me a small step forward: it is linked to the assistant and the input it gets from the VenusOS.

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