Add a second Multiplus II as a charger for a generator

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selwyn asked Jun 23, '24

Add a second Multiplus II as a charger for a generator

I have standard Multiplus II system connected to the South African grid. The backup generator that I need to use does not meet the SA grid code parameters, so a change over switch does not work.

I can change the grid code to other, but then would need an anti islanding device.

I want to add a second Multiplus (set to other grid code) for the generator to be used as a charger. It would need to be connected via an MK3-USB interface.

What support is there in the Cerbo GX for this? Where would these details be shown?

Would more functionality be available if one connected the second Multiplus via VE.Can bus with a VE.Bus to VE.Can interface?

Can one access the second Multiplus in Node-RED?

Multiplus-II battery charging Generator Node-RED multiple inverters

adding-a-second-multiplus.jpg (263.3 KiB)

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selwyn commented · Jun 24 at 01:05 PM

It would be an advantage if the Quattros could have different grid codes on their two AC inputs.

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Answer 1 · 2024-06-23T10:18:36Z

Duivert NL answered · Jun 23 at 10:18 AM

You will have to use the second multiplus independent from the other, you can not connect them both to the same cerbo gx

Maybe option is to use a multiplus 2 GX

Dont know about DC wiring also, charger multi is going to feed multi thats powering the loads, maybe there needs to be a victron isolated DC - DC converter inbetween to make it work

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Answer 2 · 2024-06-30T13:57:24Z

selwyn answered · Jun 30 at 01:57 PM

I have installed the second Multiplus with grid code other and connected it via an MK3-USB interface. A MK2-USB interface is not supported.

The Cerbo recognises the second Multiplus and lists it in the device list, but it does not appear in the dashboard diagram. The power figures in the dashboard diagram do not add up correctly as the excess power from the generator is not accounted for.

There is full support under node-RED. Here is a screen shot showing the generator details:

Addition:

I have built a new dashboard that takes the generator input and the critical loads on the second Multiplus into account. I have also added in the Eskom-se-push to set the Minimum SoC based on the load shedding stage:

dashboard-with-a-generator-connected-to-a-separate.jpg (54.1 KiB)

1720945417822.png (75.2 KiB)

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Duivert NL commented · Jun 30 at 04:20 PM

As i already mentioned in my previous post, its not going to work with an mk3 on the cerbo, it will see it but will never take it in account on the overview

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Answer 3 · 2024-06-30T20:00:14Z

vicens answered · Jun 30 at 08:00 PM

Para tener informacion de la carga en el GX se deberia poner un smartshunt en el nuevo multiplus. Como si fuese un cargador de otra marca.

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Answer 4 · 2024-07-04T13:21:10Z

bigbadbob76 answered · Jul 04 at 01:21 PM

You might not need to have the cerbo connected to the second multiplus, if you enable "has dc system" in the cerbo and if you have a shunt connected to the cerbo, then the second multiplus charge current will be recognised as an external charger and will be taken account of and displayed in the DC system box.

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Answer 5 · 2024-07-14T09:12:25Z

This is completely unsupported. The systems cannot share a common battery. The GX will only manage one inverter.

Cascading inverters is done, but they are independent systems, but it is still unsupported.

Freedom Won are likely to end your warranty as well, having a charger that is not managed by DVCC.

From the GX manual:

Only one VE.Bus system can be connected to the VE.Bus ports on the back of the Cerbo GX. The professional way to to monitor more systems is to add a second Cerbo GX

If you do require to connect more than one system to the same Cerbo GX, use an MK3-USB. Functionality will be limited:

Only the system connected to the built-in VE.Bus ports is used to generate the data on the Overview pages.
All connected systems will be visible on the Device List.
All connected systems will be taken into account for Energy consumption and distribution calculations (kWh graphs on VRM).
Only the system connected to the built-in VE.Bus ports is used for the Generator start/stop logic.
Only the Multi/Quattro (which can be a single device, or multiple together configured for three-/split-phase as well as parallel) connected to the VE.Bus port will be controlled via DVCC. Additional systems, connected to the GX device using an MK3-USB, are not controlled by DVCC and will charge and discharge according to the configuration made in those units.
In case of an ESS system, only the system connected to the built-in VE.Bus ports is used in the ESS mechanisms. The other one is displayed in the Device List only.

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