[Solved] Multiplus stops as soon as Cerbo GX is connected

DIY
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1

Hopefully someone can help me.

I have a 12 year old MultiPlus Compact 2000/24 (shorthand: MPC), and I use it totally off-grid.

Recently I bought an Cerbo GX and this have worked a few days to my satisfaction.

But recently I ran into a problem.
When I start the MPC (switching from off to inverter mode), but without the Cerbo GX connected, the MPC does function normally.

I then connect the Cerbo GX to the same 24V battery as the MPC and the Cerbo turns on normally (without the VEbus connected).

The Cerbo is shown in the VRM portal, but of course no data from the MPC is available.

As soon as I connect VEbus cable from the MPC to the Cerbo GX (see note), the MPC switch off after some delay, roughly 40 seconds.

That means, after this delay, I hear the relay clicking, the inverter stops producing 230 Volt.

In the VRM portal the MPC shows in the “off” state and I can’t get any info from the MPC, e.g. no battery voltage etc.

As soon as I disconnect the VEbus cable from the Cerbo GX, the inverter starts working again (producing 230 Volt). The error is reproducable because if I again connect the VEbus cable to the Cerbo GX the MPC stops again, and after disconnect the MPC starts inverting.

If I use the same UTP cable and connect this to a MK2-USB instead of the Cerbo, and run VEconfig on the computer, I can see and change the config of the MPC, and the MPC just works without any interruption.

note: I connected the UTP cable to the most lower right RJ45 connector (black plastic), not the Ethernet port most upper port right with metal color.

What I have done, but without success:

  • Connected an other (brand new) 24 Volt battery for the MPC

  • Connect the Cerbo GX to a complete separated battery, so the MPC and the Cerbo don’t share the same battery

  • Reset the Cerbo GX to factory defaults (via special prepared microSD card) and not configure anything on the Cerbo (and in this not configured state the problem still exist as I connect the VEbus cable tot the Cerbo)

Is this a known error and is there a fix for it?

2

I would start with updating the MultiPlus to the latest firmware.

Did you try to switch the MultiPlus from the GX device?

3

I’m not familiar with the multi layout but I would try two other things in addition to what has been suggested:

  1. Connect the Cerbo to the alternative rj45 port on the multi
  2. Make sure the soft switch is not in the off position. The soft switch is typically on the Cerbo/VRM.
4

@M_Lange

  1. My 12 yr old MP cannot be updated anymore because of old processor.
  2. I did not switch off the MP from GX device (I have seen those problems in other threads)

@Fideri

  1. That was one of the things still on my list to try, but I had no confedence that this would help, but in the end it is “a possibility to try”.
  2. I didn’t used the softswitch.

Thanks both for your suggestions.

This morning I thought, probably I have set the Cerbo to automatically update the firmware. And yes, that was the case. And because the firmware was at v3.60 (and there were several problems with it), I have 1. disables automatic updating the firmware, 2. manually updated the firmware to V3.63

And guess what?
It works flawlessly, just as before!

So the solution for this problem was updating the Cerbo firmware from 3.60 to 3.63.

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