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justinm asked

dual Quattro inverters not split phase but with split phase input?

I have a 12V and a 48V inverter both 120V quattro 5000W on completely separate CerboGX's and everything. My RV is setup for 50amp split phase shore but I only have 120V devices. I currently have the 48V inverter feeding into the 12V inverter and then only using 1 leg of 50amp shore/80amp genny (20kw 240v).

It makes more sense for me to wire in the split phase so I have the 48V connected to black and the 12V connected to red, then a shared neutral. This would make half the power running on the 12V inverter and the other half on the 48V. Would this work? The circuit panels are wired 4gauge (100amp) to the inverters and Quattro's handle 100amps.

Problem I see is I'm risking overloading the neutral if I'm running 50amp shore and if i'm pulling 50amps on each leg and they're not split phase it could overload? BUT if the inverters are pulling the load then there isn't an issue since the neutral only carries the unbalanced load, if its passing through then the output will still be split phase so still isn't an issue. The only issue is if its charging while passing through or assisting which i'm unsure of.

I was thinking about just swapping my entire 12V with another 48V and going traditional split phase, but running separate systems works better as I'll have full redundancy as if one system goes down only half the outlets die. My 48V has solar and my 12V has alternator so when driving i'm able to pull 3000w from the alternator which would be ideal as I can run the front AC and it still charge my 12V. Only 12V devices are lights, water pump and macerator toilet so not huge loads. Another benefit is I usually just plug my coach into 15amp shore when at home since I have solar and just need piece of mind. I plan on also running a 15amp plug to each inverter so I'm moochdocking at a friends house I could run 2 15amp extension cords into separate breakers and effectively get double the input power. Or I can just plug one or the other in to charge either system depending on needs. The Quattro5000 has a minimum input of like 13.2 amps which is another issue i'd be avoiding.

Another issue is i'm planning on setting up a buddy plug to use when friends are camping with me and also to power my house using my RV's genny since its 20kw. Friends aren't a big deal because 240V appliances in an RV is rare and I can just make sure they don't have it or make them use a 50 to 30 adapter to be sure. But my house needs 240V for HVAC and such. I plan on wiring the buddy plug to the output2 on the inverters as its not used. Is there a way for the inverters to just passthru the split phase from the genny or would I need a 2nd buddy plug connected directly to the genny? I need friends to use the inverters so we wouldn't need to run the genset and just run off battery/solar but if a power outage at home IDC if i'm running the genset the entire time.

I plan on wiring it up, setting the input limits on both inverters to 25amps and testing the system so no risk to anything. After all is good I can hookup a clamp meter to the neutral and see how the load is.

MultiPlus Quattro Inverter Charger
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3 Answers
Justin Cook avatar image
Justin Cook answered ·

With respect, please engage a reputable, experienced AC and DC systems electrician/installer before you experience potentially catastrophic failures of your system.

You can use Victron's where to buy map and sort by "installers", or contact a distributor or dealer near you and they'll often have a short list of independent installers in the area who they'd recommend.

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justinm avatar image justinm commented ·
This isn't a standard setup and I've been looking and haven't found others trying this setup.


It's not so much about an experienced electrician but specifically how the Victron inverters pass through power when not inverting. If passthru is actually just passing through then phase isn't affected and I'll have split phase to the breakers, if it's doing something else then there's a possible issue.

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mvas avatar image
mvas answered ·

You wrote ...

 I currently have the 48V inverter feeding into the 12V inverter and then only using 1 leg of 50amp shore / 80amp genny (20kw 240v).


Problem I see is I am risking overloading the neutral if I am running 50amp shore and if i am pulling 50amps on each leg and they are not split phase it could overload?

This really needs a wiring diagram. Are you saying, Currently, only 1 Leg of the 50 Amp Shore Power connects to the AC IN of the 48 Volt Quattro? And then the AC OUT of 48 Volt Quattro connects to the AC IN of 12 Volt Quattro? And each Quattro supplies power 1/2 of your Split Phase Main Breaker Panel?

What is the rating of your Main Circuit Breaker Panel?
Is it - 50 Amp 240v/120v Split Phase?

If YES, then you could potentially overload the Neural Bar in the Main Panel.
Without a true Split-Phase configuration, how are you limiting the Neutral Bar to 50 amps max?
In Battery Mode or Assist Mode your Neutral Bar could have more than 50 amps.

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justinm avatar image justinm commented ·
Kinda. Right now 1 leg of the 50amp goes to the 48v then it goes out from 48v to in of 12v then out to both legs to my panels. So red and black are combined on out1 of 12v.


Circuit panels are 100amp rating and 4 gauge wiring. The genset is 20Kw with 80amp breakers for 240v.

I'm currently working on rewiring so each inverter powers each leg separately. I don't need to worry about overloading the panel or it's neutral as it can handle 100amps as can the Quattros.

What I have to worry about is overloading the 50 amp shore neutral but I don't think this is possible.

50a/240v is 12,000 watts and the only time I could use that much power is if I'm running all 6 rooftop AC units which even then it'll be just for a few minutes which I still think ill have a couple thousand watts. Maybe if it was also full charging both battery basks or I was cooking it could.

But even so the input is split phase so at least some of the power will be offloaded through the 2nd hot. Say if both battery banks were charging 10amps and it was passing through 40amps at a minimum the charging would be on opposite phase so would negate each other.


I'll have a wiring diagram soon

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justinm avatar image
justinm answered ·

Here's the wiring diagram but IN2 will be the genny and wired like in1 is. Was too complicated adding it. Basically the neutral input will be shared between both inverters then the neutral output will be shared between both inverters. I just rewired the coach like this and all good but only have 15amp plugged into the black of the 50amp side, Tomorrow i'm getting new 15amp plugs so can pick which one it goes in.

newwiring.png


newwiring.png (222.6 KiB)
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mvas avatar image mvas commented ·
OK, I understand, now. So, my only concern is ... what happens in Battery/Inverter Mode? The two Quattros will not stay in-sync. The PHASE between the two Quattros may not cancel the amps in the Neutral Bar. The amps could add together 80 amps = 40 amps + 40 amps. You must manually balance the loads on both legs and verify the current in the Neutral Bar is always below 50 amps.
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justinm avatar image justinm mvas commented ·

Everything is 4 gauge and rated for 100 amps except the 50amp shore cord on the inputs. Is there any way I can overload the shore cord coming IN to the inverters? I don't think it's physically possible regardless on how out of phase things are after the inverter.

I'll make sure I don't have enough power to go over 100amps total and if I do I could even wire up each circuit panel (I have 2) so they have their own 4 gauge wiring to the inverters thus doubling my neutral to 200amps, since the Quattros support it

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