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fulltarr avatar image
fulltarr asked

Split phase requirement for 240 volt HVAC system

Hello everyone! I'm new here and really enjoy the extensive knowledge Victron puts out to its customer base!

So, here is my situation. I have the need for 240v split phase (SP) on my RV due to the installation of a 240v inverted mini split HVAC system. I've heard that there was a method to get one Multi (L1) to passthrough/charge and another Multi (L2) to invert from batteries to make 120/240 SP when incoming power is only 120v single (Obviously not as efficient but with solar and many kWh on hand it could work). I've also seen Victron's recommendation to use a 240v inverter coupled with an autotransformer to make 120/240 SP but that would be problematic when the incoming power is only 120v because I would need an autotransformer to make 240v. That's two autotransformers! Not to mention, I already installed two 120/3000/70 Multis configured in SP.

Now to the question, using the method above where you have one Multiplus passthrough/charge L1 and the other invert for L2, how do you program it?

Or another option would be to utilize a skylla-ip65 120/240 charger for when incoming power is not ideal?

Hope this makes sense. Thanks!

AutotransformerSkyllasplit phase
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snoobler avatar image snoobler commented ·
Posting as a comment because I'm not 100% sure.


I don't think you need to do anything programming-wise aside from having the L1 MP AC charger properly configured for the amount of AC input. Would also make sure power assist is enabled in case you overload the AC in put on L1.


I think you just need to apply 120VAC to the AC input of the MP providing L1. I believe it will sense AC input, enter passthrough, and the 2nd MP will automatically sync with the AC input to properly provide L2 from batteries.




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fulltarr avatar image fulltarr commented ·
Okay. I've been thinking about that I'll have to make my own adapter because RV cheater plugs combine L1 and L2. Tomorrow's test for sure! Thanks!
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snoobler avatar image snoobler fulltarr commented ·

So you have 50A service? Yeah. You could fab up a custom 30A adapter that didn't jumper L1/L2.

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fulltarr avatar image fulltarr snoobler commented ·
Tried sending 120v to just one inverter that was set to L1 and the other one was set as L2 (float). It would not connect to mains no matter what I tried... I don't like that N. America kept split phase system- makes everything so difficult!
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1 Answer
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mike-g answered ·

I installed a dry transformer, which outputs 23A split phase 240VAC from single phase 120VAC 30A. I used a rotary switch to select it when on single phase 30 A power. The other selection on the rotary switch passes through 50A split phase to the 2 Quattros.

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