question

mterman avatar image
mterman asked

Multiplus II turning off, than on again

Does anybody have any idea how can I debug this behavior?

The batteries are Pylontech, they are connected to Cerbo GX vie BMC Can as per manual. Everything is working on that part. Also, MPPT is behaving normally.

When I connect the Multiplus II to the Cerbo GX via Ve.bus, Inverter goes from inverting to off, then back to inverting, then back to off ...

If it's not connected to the Cerbo stays on, and keeps inverting.

It is now connected to Cerbo via MK3 dongle, and that used to work as expected. The inverter was shown in the console, and on VRM. I could see the AC consumption ...
After the update of the Cerbo to the v3.00, this stopped working. I can see the inverter in the device list, but I can't see the AC usage in VRM or overview pages...


Multiplus-IIcerbo gxDVCC
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7 Answers
luphi avatar image
luphi answered ·

make sure to have both running the latest version which are 3.10 for the Cerbo and v506 for the Multi. have you tried a different cable?

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mterman avatar image mterman commented ·
Hello,


Yes, everything is up to date. I have tried multiple different utp pathch cables.

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lifeingalicia avatar image
lifeingalicia answered ·

.....After the update of the Cerbo to the v3.00....

I think 3.1 is the latest

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mterman avatar image mterman commented ·

Yes, you are correct, the latest version is 3.10.
But my problems started before version 3.10 was released. And updating to the 3.10 did not help.
Everything is up to date.2023-09-14-084040-vrmvictronenergycom-0555f124406f.png

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2023-09-14-084040-vrmvictronenergycom-0555f124406f.png (24.1 KiB)
aaront avatar image
aaront answered ·

Make sure the ethernet cable is not running with the battery cables

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mterman avatar image mterman commented ·
It is not. It comes near the battery cables when entering the Multiplus, but that is unavoidable. I tried different lengths of utp cables, in different positions...
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luphi avatar image
luphi answered ·

Make sure, to not terminate the VE.bus

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mterman avatar image mterman commented ·

Hello,
It's not terminated.

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janvi avatar image
janvi answered ·

Had your described on / off failure caused from a loose DC wire at the Multiplus. The loose wire was already very hot. After cooling down, the MP2 starts again and heats up until disconnection. For this reason: Always double check all terminal screws and use proper crimping pliers.



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mterman avatar image mterman commented ·

All DC connections are OK. The system is working and is stable. It has been working for over a year, it's in constant use 24/7. AC consumption was visible trough connection to Cerbo via MK3. But that stopped working after the update to Cerbo firmware 3.XX.
It's only when I connect MultiPlus to the Cerbo via Ve.Bus that this starts to happen...

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janvi avatar image
janvi answered ·

Did you check the PE connection for your MP2 ? Missing PE may cause common mode errors from occasionally static dischargings.

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mterman avatar image mterman commented ·
Hmm, I will check that! Meaning that I will recheck the connections.

Every part of the equipment is grounded to the common PE bus including MP2 and Cerbo, but I will recheck the connections!

Thank you for the hint!

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mterman avatar image
mterman answered ·

Hello, me again. I still haven't resolved this problem.

Does anybody know could this problem happen because of Cerbo's lack of PE connection?

Cerbo GX doesn't have a point to connect PE to, no grounding lug or anything. I suppose that for the internal GND Cerbo is using negative of the power supply input. My Cerbo is powered directly from the batteries. Multiplus II has a PE lug connection and that is connected to the system PE bus. My batteries are not grounded, meaning the negative pole is not bound to PE. Batteries are pylon-tech, they also have separate PE lug, it is also connected to the system PE bus.

Could the problem be that the Cerbos and Multiplus GNS connections are not the same GND?
Here is the diagram of the Ve.Bus pinout I found:
13877-1602788734429.png




13877-1602788734429.png (27.6 KiB)
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