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reviv asked

2 x 120V (MultiPlus-II 24V/3000)

I am trying to clarify the true purpose of the 2nd 120V output. I see many explanations that say the 2nd AC Output is used to supply the second leg of a 50A RV. While you can do this, I think this can happen with or without the the 2 x 120V option?

In reading the manual, I believe I understand the following:

1.) In both passthrough and assist, power will be supplied to both L1 & L2 of AC - OUT 1. If input is single phase, L1 and L2 will be joined.

2.) AC - OUT - 2 is only passthrough and never power assist. So the main purpose is to isolate some circuits that can never draw from the inverter / batteries.

Multiplus-II
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tk-421 avatar image tk-421 commented ·

Without the 2x120 option, you'd have to feed both legs of your panel from only one leg of a split-phase input. The AC IN and AC OUT 1 and 2 don't even have an L2 terminal to connect. If you feed both legs of your panel from AC OUT 1 then they both get inverter power. If you put one on AC OUT 1 and one on AC OUT 2, one of them goes dark when there is no AC input. But when there is AC input, both are still fed from L1 of that AC input (because there's not even any place to connect L2).

The 2x120 option allows you to pass through proper split-phase AC power when present, and tie L1 and L2 together when split-phase input is not present.

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derrick thomas answered ·

As stated in the manual and the excerpt you posted, acout2 is primarily used for loads which are never intended to be powered from the inverter either in invert mode or power assist. For most people these loads would be things such as air conditioners or ac water heater. The 2x120 models were primarily intended for use in north American RV's which can often times be plugged into 50amp split phase 240 or single phase 30amp 120. The 2x120 makes for a very simple installation in these types of vehicles.


Edit to add:

Both ac out 1 and ac out 2 have both L1 and L2 legs, so both outputs are capable of supplying both legs of the RV breaker panel. If someone was going to use ac out 2 for the intended purpose of supplying loads in passthru only, ac out 2 would feed into a separate panel for those loads only. In my case, I would feed the entire RV from ac output 1 using 2 multis paralleled as I have a 275 amp alternator that runs 2 air conditioners while under way.

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