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mtnhillsman avatar image
mtnhillsman asked

Multiplus ii 12/3000/120-50 2x120v vs 24/5000/120-50

Hi - i have a Multiplus ii 12/3000/120-50 2x120v I've been running for about a year in a camper outfitted with solar and a Victron 150|100 MPPT. I'm starting to realize the limitations of 12v and am looking to upgrade to a 24v Multiplus ii and also add some capacity.

All research at this time points to the 24/5000/120-50 being a good fit but most sites list it as '230VAC output, European Voltage, not for use in USA"

My current Multiplus ii I've always been under the impression it's a 220v unit since it feeds my camper's 50a 220v panel. In fact obviously i don't want a 110v unit since it'd combine both hots of the panel. is there some discrepancy between a '2x120' and '230v' ??

The operation I'm looking for is just like the current 12/3000 Multiplus ii works. plug in 50a 220v and the unit patches the hots directly through to the panel. When disconnected from the grid, inverting, or in assist mode, the hots are combined and each side of the panel shares the same 120v feed.

Any advice on this is much appreciated. Really confused why the 24/5000 is so consistently listed as European.

Multiplus-II
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4 Answers
randallemarshall avatar image
randallemarshall answered ·

You're mixing European 230v single phase with American 240v split phase. If you are currently using 120v I assume you want an American unit. But you also mention it's feeding 220v? Are you sure your unit is not feeding the same 120v phase to both busses in your camper instead of 240v split phase? Assuming you have no 240v split phase loads this would be fine.

If you need 2 120v hots you will need 2 separate MP-2 units that each supply 120v to provide split phase. But I don't think this is what you're looking for.

There is a 12v and 24v Multiplus 2 that can take a 240v split phase input and pass it to your system. In inverter mode it will mirror 120v on the same phase like mentioned above and 240v split phase loads will not function.

https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-II-3kVA-2x120V-EN.pdf

If you are considering 48v there's also a 12v, 24v, and 48v Multiplus 2 without the split phase input, only single 120v phase, that you can again mirror like above to both legs.

https://www.victronenergy.com/upload/documents/Datasheet-MultiPlus-II-48V-3kVA-35-50-120V-EN.pdf

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mtnhillsman avatar image
mtnhillsman answered ·

ah yeah so now i'm starting to understand the difference between single phase and split phase. so yeah i'm looking for split phase 220v. I never quite understood i guess that in my current setup i couldn't run 240 split phase loads such as a welder or household dryer. Not that i would, but, just trying to better understand what's going on.

The unit you suggest however is close but I really want to move up to a 5000VA unit so i can run both roof ACs with ~1500W of solar coming in and a mini honda generator supplementing so the inverter would remain in assist mode providing roughly a 2400 watt load. i think the 3kva will do it but it's really pushing it beyond 90%.

I definitely don't want to run two units. Space constraints and that just seems overkill. I'd rather avoid 48v too. 24 seems to be a good sweet spot. but i suppose if there are no options for a 24/5000 unit I'll have to investigate that.

Thanks for the help with this.

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Kevin Windrem avatar image
Kevin Windrem answered ·

The unit you currently have has a single 120 volt inverter. When passing shore power to the outputs, the split phase input is passed to the output, but when inverting, both legs get 120 volts in phase, so no 240 volts between them.

Increasing total power capability will require a second Multi to handle the split phase120/240 volt power in and out.

Note that running two Multis in split phase configuration requires special attention on order to accept 120 volt single phase shore power.

You need to turn off switch as a group. With 120 volt shore power, one Multi will accept AC input and pass that through to the output. The other Multi will remain in inverter mode and pull power from the battery and/or the first Multi's charger and/or PV charger.

You also need to enable "floating phase" in order to accommodate two legs of three phase power found at some campgrounds.

You could run a 230 volt European unit adjusted for 240 volts followed by an autotransformer to create the 120/240 split phase power for your two-leg panel but it's another large-ish unit. This setup is shown here:

https://www.victronenergy.com/upload/documents/AT-1-split-phase-240V-to-120-240V-with-Quattro-240V.pdf

Using a single 230 volt Multi would not allow 120 volt shore power to be used unless another autotransformer were fitted before the Multi to step up the voltage to 240 volts.

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mtnhillsman avatar image
mtnhillsman answered ·

yikes none of the last answer sounds like a great solution for my situation. it seems like 90% of the time i'm operating with the single phase inverter joining the two legs of the panel. What originally made me go with the multiplus ii was the fact that it's turn key when i get to a full hookup with 240.

the 12 or 24v multiplus ii has a 3000va limit which means 2400 watts when the ambient temperature is higher. can i live with this? maybe. as i expand my solar and/or as i upgrade to higher wattage panels i'd like to be able to run both ACs but thats the most intense use case.

is there a unit out there that will offer 5000 VA, operate on 24v DC, and still pass the hots of 240v directly to the panel and shut off the inverter as the 3k multiplus ii's do?

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Kevin Windrem avatar image Kevin Windrem commented ·
No Victron single-unit solution for more than 3000 VA and split-phase support.

The 3000 VA unit is good for 2400 watts at 25 C and derates at higher temps: 2200 @ 40 C (100 F).

If you decide you need to run both air conditioners at the same time and wish to stay with a split phase system then you'll need two Multis.

You could rewire for 120 volt operation and feed both legs of your panel from a single leg as long as you keep neutral current under the bus and wiring size (probably 50 amps). That cuts your available power from 12,000 to 6,000 watts for the entire RV. Then you could run with a 5000 watt 120 volt Quattro. But Quattros are quite a bit larger and heavier.

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