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panosgr avatar image
panosgr asked

Can a Cerbo GX address/manage 2 MultiPlus units and a Skylla-i?

I want to install Victron units in a boat and need assistance as I am totally confused regarding the Cerbo GX and its capabilities.

1) The boat is located in Europe and has already a Victron Skylla-i 24/100 which is currently charging the service battery bank. The service battery bank and the engines battery bank consist of lead batteries.

2) I plan to install 2 additional "MultiPlus 24/5000/120" units

The 1st unit will function as charger/inverter (charging the service battery bank (the Skylla-i will charge the engines instead) and providing via its inverter circuit AC to the fridge, freezer and ice maker).

The 2nd unit will function ONLY as an inverter to the AC plugs of the boat. The reason why I choose to install a MultiPlus (only as inverter) instead of getting only an inverter model is because I need the fast switching (UPS function). The 2nd unit will draw DC power from the service battery bank (ie, the same as the 1st unit)

3) I also wish to install a Cerbo GX & GX touch 70 as I (a) want to be able to monitor locally the status of the devices and (b) want to remotely be able to get notifications from the cloud on my mobile Victron app


Here is where the confusion is: reading elsewhere in the forum the "Setting up 2 Multiplus units with a Cerbo GX" thread I am realizing that maybe the Cerbo GX will be unable to address/monitor both Multiplus units ALTHOUGH it has 2 "Ve.Bus" connections available. Furthermore I have no idea how to connect the Skylla-i to the Cerbo GX and whether also it will be able to monitor it as well.

Please note that the MultiPlus will NOT BE running in parallel. Each will be a standalone unit.

I read elsewhere that maybe connecting the 2nd is possible with a MK3-USB cable is possible but the functionality will be crippled (no idea what will be lost...) and that maybe the Skylla-i can be connected via the "Ve.can" connector.

Can please somebody take me out of my misery?

Why something so simple cant be clearly found somewhere?




Multiplus-IIcerbo gx
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5 Answers
Mike Dorsett avatar image
Mike Dorsett answered ·

This type of application is not documented as it is a fairly unusual case.

The multi is capable of operating both as a ups and shore charger at the same time. When the shore power dips or drops, the change-over is fast enough to prevent a standard computer power supply from noticing.

You don't say what type of house bank (lead or lithium) you will be using or its intended capacity...

If you need to keep the ac circuits separate, this could be none, even if the inverters are configured for parallel operation - but this is not recommended. It would also be possible to arrange for a load shed device to remove AC from the fridge/freezer/ice maker circuit under certain circumstances.

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panosgr avatar image panosgr commented ·
All batteries onboard (engines and service banks) are lead.

I have updated my initial posting to address this.

Thanks for your answer, however now I am even more confused than before!

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Kevin Windrem avatar image
Kevin Windrem answered ·

The short answer is no, a GX device can only control one Multi/Quattro or a collection of them configured as multiple phase and/or parallel.

Separate control of individual Multis is limited to one Multi with full control and the other only as a device in the device list. The second unit is not integrated into the system.

The Skyla MAY appear as an AC Charger device in the GX device. However there is no display of the charging status in the flow page in the stock code. GuiMods may add a tile for it however.

You might consider a single Multi or a two in parallel, along with the Skyla. The Skyla could charge the house or starter batter bank.

Some people separate the charging and inverting functions on boats that see both 120 volt 60 Hz and 230 volt 50 Hz power. This allows the AC in the boat to remain at the same voltage regardless of the shore power connection. The Skyla will connect to either shore power voltage/frequency. This does mean however that the charger and inverter are both working all the time.

If all your loads are on the house bank, you may only need a trickle charge for the starter battery which could be handled by a DC-DC converter from the house bank.

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panosgr avatar image
panosgr answered ·

Kevin:

"Separate control of individual Multis is limited to one Multi with full control and the other only as a device in the device list. The second unit is not integrated into the system.

The Skyla MAY appear as an AC Charger device in the GX device. However there is no display of the charging status in the flow page in the stock code. GuiMods may add a tile for it however."


So I take it as a fact that the GX can control only ONE Multi. When you say that the 2nd will appear only as a device in the device list does this mean that the GX wont show anything about it? (apart its name). No metrics, no readings, nothing??

Same question for the Skyla: no metrics, no readings, nothing? If indeed nothing, what about the tile you mention in the GuiMods? If I install GuiMods will it actually show anything useful?


"Some people..." I am sorry but starting from this sentence I failed to understand all from that point on...


Two more questions:

1) can the GX device fully program/edit ALL the MultiPlus parameters or SOME and thus a MK3-USB cable and laptop are needed?

2) MultiPlus: on a bad AC input (lets say 185 AC volts instead of 220 AC) can the Multi compensate for the extra volts needed by inverting the missing AC volts from the battery bank OR does it FULLY provide the 220 AC volts inverted from batteries?



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Kevin Windrem avatar image Kevin Windrem commented ·
"Additional" inverter/chargers will appear in the device list and their menus will display their values. The values will not however be integrated with other components in the system menus and in the flow pages.


ALL configuration of the Multi must be done via VictronConnect or veconfig. Nothing can be configured from the GX device.

No "boost/buck" functionality often found in a UPS. In the Multi, when the grid is present, the Multi will connect the AC input to the AC output so incoming voltage and frequency will appear at the output. If the incoming AC voltage drops below minimum, the AC input will be disconnected and the AC out supplied by the batteries.


The GX device controls ONE multi/quattro OR a collection of them configured as parallel and/or multi-phase. The collection is presented to the GX device as a single unit with increased capabilities (e.g., multiple phases).

The "some people" discussion:

Boats often find themselves at marinas with varying AC voltage and frequency. Because the AC devices on the boat will probably not be dual voltage/frequency, some means of accommodating different shore power sources is needed. One way to do this is with a step up/step down transformer at the input of the Multi/Quattro. The transformer takes incoming shore power at say 120 volts and makes it 240 volts. This works if the AC devices can handle 50 and 60 Hz AC frequency.

What I was describing is a method to make the AC available on the boat always constant. The shore power ONLY feeds a charger capable of handling 120 or 230 volt shore power and 50 or 60 Hz. This charges the battery bank. (Often multiple chargers running in parallel are required.) The inverter then always runs off the batteries making AC at a constant voltage and frequency regardless of the incoming shore power.

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panosgr avatar image
panosgr answered ·

Kevin:

"Additional" inverter/chargers will appear in the device list and their menus will display their values. The values will not however be integrated with other components in the system menus and in the flow pages.

As long as I can read values (AC volts, DC volts,amps charging, etc) its fine. Will I be able to see those?



"ALL configuration of the Multi must be done via VictronConnect or veconfig. Nothing can be configured from the GX device."

Correct me if I am wrong:

VictronConnect needs a MK3-USB cable and a local laptop.

"veconfig" = "remote veconfigre" (by exporting/importing from the cloud)



"No "boost/buck" functionality often found in a UPS. In the Multi, when the grid is present, the Multi will connect the AC input to the AC output so incoming voltage and frequency will appear at the output. If the incoming AC voltage drops below minimum, the AC input will be disconnected and the AC out supplied by the batteries."

This ^^^ statement contradicts the Victron advertised "PowerAssist" function. It mentions the work "supplement" which -if I understand correctly" that any AC volts missing will be added by inverting from the DC bank:

PowerAssist - Boosting the capacity of shore or generator power This feature takes the principle of PowerControl to a further dimension. It allows the MultiPlus to supplement the capacity of the alternative source. Where peak power is so often required only for a limited period, the MultiPlus will make sure that insufficient shore or generator power is immediate

If what you are implying is correct then its is a TRUE/FALSE condition: if AC power IN exists and its above set thrsehold (for example 218v) then pass it directly to AC out. AC in volts below 218 will set on the inverter then ALL AC power needed will be 100% inverted from DC. Is this what you actually mean?


As for the "some people" discussion now I understand what you mean. However where the boats is/navigates the only issue with AC shore currents is the volts variation, not variations in frequencies.


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Kevin Windrem avatar image Kevin Windrem commented ·

Yes, you can see the inverter/charger's parameters in it's menu.

Yes you need an MK3 USB adapter to configure the Multi with a direct connection. Windows, Mac OS or Android can do the configuration via VictronConnect.

You can use VRM to do a remote configuration which does go THROUGH the GX device instead of the MK3 USB adapter. You need veconfig for that which is a Windows only application.

PowerAssist can add current to the incoming AC input but can't change the voltage (or frequency). The result is additional power at the AC output beyond what the grid can supply.

Here's an explanation of PowerAssist starting at chapter 1.10.

https://www.victronenergy.com/upload/documents/Technical-Information-Achieving-the-impossible-EN.pdf

One way to accommodate different shore power voltages is to have a transformer with different input taps for the different voltages. You set the tap to achieve your desired output voltage. There are some devices that will also do this automatically. Victron does not manufacture such a device however.

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panosgr avatar image
panosgr answered ·

Kevin:

thanks for your valuable information.

One way to accommodate different shore power voltages is to have a transformer with different input taps for the different voltages. You set the tap to achieve your desired output voltage. There are some devices that will also do this automatically. Victron does not manufacture such a device however.

I am not aware of any product that can do such a thing. You mean that these products can "fix" the problematic AC IN power? (just like I was hoping that the Multi could). Like having a 185 AC volts IN and upping it to 220 AC out? If yes, can you please point me to any such product(s)?


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Kevin Windrem avatar image Kevin Windrem commented ·

One such device:

https://hughesautoformers.com/voltage-boosters/

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