New Victron Multiplus-II 12/3000/120-50 designed specifically for RVs with 30A/50A input flexibility available MARCH 2021

Firstascent

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Mar 7, 2020
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154
three A/C units! Ok now makes sense. Would probably not need this for a van build then.

I understand the part about the 4 wires, the receptacle has L1, L2, N, and PE/gnd. Theoretically, you could run US 240v appliance off this if your rv had it. I was wondering if any RVs actually had them.

Next question: why don't RVers just install more solar and a bigger inverter then? Solar panels are cheap nowadays and you have the roof space. Difference between 3kw and 5kw is only ~$300 (edit: more like $700, still) and a ~13kWh batt is like ~$2000 with reputable Eve cells. I think @cinergi has such a system. Then you don't need to be tied to a plug and it should pay itself within a year or two?
The inverter itself is only designed to output 120v. I don't think any RV'ers have any 240V appliances, maybe somewhere out there (never say never) but it's just not needed or common, and would be something custom someone did on their own.

Until a few months ago, for Victron anyway, didn't offer a 50a/120v/3kw option, this is their new MPII line. The 'old' MultiPlus (which is still a good option) does have a 5kw option on the Quattro line. It all depends on how much AC power you need vs DC.

Adding more solar panels comes down to cost and space. Depending on your current setup, adding another solar panel, or two or three, could also mean needing another MPPT controller as well, so more costs. Everything adds up quickly :) Then physical space, and weight is a concern on mobile applications at least.

The inverter doesn't care how much solar panels you have though, only how much load it needs to handle.

The Eve cells are a great solution and probably closer to $3k for ~13kwh now, prices are going up everywhere. It's also a VERY much so DIY thing to build your own and supply your own BMS to keep them safe, build your own compression enclosure, etc. Very much doable with a lot of great info out there, but not for everyone.

I have 16 of the Eve cells myself with this new MultiPlus II. So I'm all for it, but it's definitely more work than say buying a battle born battery which can be an easy piece of mind for most folks.
 

Firstascent

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Mar 7, 2020
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154
The roof of an RV is like an obstacle course. Vents, skylights, antennas, A/C unit, they're all over the place and in random positions. Trying to fit solar panels is like playing Tetris on level 10.
haha yes, and this! your roof is never a blank slate.
 

corn18

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Sep 9, 2021
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305
The best thing about the new MPII 12/3000/120x2 is how easy it is to hook into a 50A RV system. The 50A transfer switch and 2 phase pass through make it so simple even I could do it.

That and the power assist feature are the cat's meow.

As far as I know, there isn't anything else like it on the market.
 

cinergi

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Aug 9, 2020
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1,165
three A/C units! Ok now makes sense. Would probably not need this for a van build then.

I understand the part about the 4 wires, the receptacle has L1, L2, N, and PE/gnd. Theoretically, you could run US 240v appliance off this if your rv had it. I was wondering if any RVs actually had them.

Next question: why don't RVers just install more solar and a bigger inverter then? Solar panels are cheap nowadays and you have the roof space. Difference between 3kw and 5kw is only ~$300 (edit: more like $700, still) and a ~13kWh batt is like ~$2000 with reputable Eve cells. I think @cinergi has such a system. Then you don't need to be tied to a plug and it should pay itself within a year or two?

Yeah - I have a unicorn RV ... 240V needed for mini-split and it was a custom-build RV so the roof was clear and it was easy to get 10 335 watt panels up there. My system is relatively inefficient (dual 5k inverters idle power is a lot, for one) and combined with some shading I get here in AZ, I'm only producing 8kWh per day so I eventually have to plug in because that's about how much energy I typically use in a given day (without air conditioning).
 

sparklehunt

New Member
Joined
Aug 19, 2021
Messages
29
The best thing about the new MPII 12/3000/120x2 is how easy it is to hook into a 50A RV system. The 50A transfer switch and 2 phase pass through make it so simple even I could do it.

That and the power assist feature are the cat's meow.

As far as I know, there isn't anything else like it on the market.
So you have the ACin wired up to a 50A RV plug style (with L1,L2,N,PE)? What happens when you encounter a 30A style plug? Can you physically have two styles of female plugs wired in parallel on ACin (so L1,N,PE branch off to another plug)?

Also can you explain what the transfer switch lets you do and what are the benefits of a larger A one?

some shading I get here in AZ, I'm only producing 8kWh per day
very weird. I think AZ and I think sun. Must be a good amount of shading.

Question that is related to OP: this MPII 12/3000/120x2 is raved about...couldn't you use a 230VAC Euro model + autotransformer? The ACin would have L,N,PE which would connect to a 50A plug L1,L2,PE. Neutral of the plug is then not used. I guess the input wouldn't accept 120VAC 30A style RV plugs then
 

corn18

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Sep 9, 2021
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So you have the ACin wired up to a 50A RV plug style (with L1,L2,N,PE)? What happens when you encounter a 30A style plug? Can you physically have two styles of female plugs wired in parallel on ACin (so L1,N,PE branch off to another plug)?

Also can you explain what the transfer switch lets you do and what are the benefits of a larger A one?


very weird. I think AZ and I think sun. Must be a good amount of shading.

Question that is related to OP: this MPII 12/3000/120x2 is raved about...couldn't you use a 230VAC Euro model + autotransformer? The ACin would have L,N,PE which would connect to a 50A plug L1,L2,PE. Neutral of the plug is then not used. I guess the input wouldn't accept 120VAC 30A style RV plugs then

The MPII is smart. When it senses a single phase input (30A RV input), it ties L1 and L2 together inside the inverter. That's what makes it awesome for RV's.

This also applies to your second question. I don't know of any other inverter that can pass 50A @ 2 phases through with the internal auto transfer switch. When plugged into 50A shore power, the MPII passes both legs through up to 50A. That makes it really easy to hook into an existing 50A system.

You got it right with the Euro model. It still only passes one phase through.
 

corn18

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Sep 9, 2021
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305
Here's my wiring diagram:

DC wiring 290RL.jpg

And a pic of the inverter installed:

IMG_5086.jpg

So simple. The second wire from the top is AC in from my power reel. I just used the existing 6/3 Romex and cut in a 50A breaker then to AC in. Then I just hooked up the other end that goes to the power panel to AC1 out. Just used the same cable. This is one time where I was happy that Forest River used way too much wire. Even after splicing in the MPII, there's still too much Romex, but that's ok.

All the batteries and fuses are in that cubby on the left. Solar charge controllers mounted to the top of the compartment. Cerbo is above the MPII. This area is all heated and cooled, so everything should stay nice and comfy.
 
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