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lavapower avatar image
lavapower asked

MultiPlus-II 12/3000/120-50 2x120V PowerAssist Questions

Hi Everyone,


I've done a lot of reading of the 2x120v manual (especially helpful are the power flow diagrams) and posts (thank you @Kevin Windrem for your detailed posts related to the 2x120v) before posting this. I want to confirm a couple things then seek advice on one point.


The way I understand PowerAssist on the MultiPlus-II 2x120v is that the "Input current limit" setting only applies to AC-In-L1 and not AC-In-L2, correct?


I ask this specific question because the "dogbone" adapter (NEMA TT-30P to 14-50R) splits one 30A hot into two therefore feeding AC-In-L1 and AC-In-L2 and tricking the MultiPlus into thinking it has a split-phase connection. With that, the input current limit setting only half-works, right?


Now for my advice question. Would it be better to build my own 30A to 50A adapter without a bridge to only feed AC-In-L1 so PowerAssist works properly?


I've been tripping 30A breakers despite setting the input limit even down to 20A and I suspect this is why.


Thank you,

Stephen

Multiplus-II
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2 Answers
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derrick thomas answered ·

1. You are correct in that power assist/current limit only applies to ac input L1 and not AC input L2.


2. When connected to 30 amp shore power using a 30 to 50 adapter, the 2x120 recognizes that there is no phase difference between L1 and L2 input, rejects L2 input, and 'bridges' L1 and L2 outputs. In this situation the AC input current limit and power assist is applied to L1 and L2 outputs combined, and will show on the display as L1 input and output, it will not show output on L2.


3. If you build your own adapter with just L1 output, or use an off the shelf with L1 and L2 outputs makes no difference. The multi will behave exactly the same.


As far as tripping breakers even with the AC input limits set lower than the supply circuit, make sure the multiplus switch is in the 'on' position and power assist is enabled in the configuration. If you have selected 'charge only' then power assist will not function and you can easily go over the ac current limit.

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lavapower avatar image
lavapower answered ·

This is really good information and it makes sense now about the MultiPlus seeing no phase difference because the normal connection is dual/split phase at 180 degree difference.


Thanks @derrick thomas. I'm amazed at the Victron community and I'm grateful to be a part of it. I hope I can help someone some day but with all the expert knowledge here, at least I know I'll keep learning too.

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