AC-out-1 works and the batteries are charging however while charging in bulk the AC-out-2 stays off.

Hi, I am just starting out with Victron, and want to ensure that I have understood the Multiplus II's AC logic correctly (specifically, in ESS mode).

It's clear enough from documentation that AC-out-1 is protected by the battery and always live (provided no fault condition), and AC-out-2 is only energised when power is present on AC-in. I also gather from Appendix B of the manual that the transfer relay is normally closed when AC-in is live and that, to the MP2, there is no difference between loads on AC-out-1 and AC-out-2.

Appendix B also shows that current is measured at two points: directly at the inverter output, and at AC-in. Between them, so far as I can work out, they allow the MP2 to detect and prevent overload conditions on the inverter, to implement PowerControl, and anyway to limit current drawn on AC-in by the charger according to something less than the breaker supplying AC-in. PowerAssist is implemented by means of an ET112.

That all seems fairly straight forward. (Have I missed anything?)

Does it matter if there are loads, possibly quite large loads (oven, 3kW kettle, 2kW AC etc) between the ET112 and AC-in, or do they have to be connected to AC-out-2? In an ESS situation, do I ever need to use AC-out-2 for any purpose?

It seems not, so far as I understand it. Their current draw will still be seen via the ET112 and, because AC-in, AC-out-1 and AC-out-2 are all directly coupled via relays, even loads upstream of the inverter will benefit from PowerAssist (so long as grid power is present, of course). This is also why PV inverters can be installed in parallel with any of the AC ports on the MP2: everything is galvanically connected when grid power is present.

The one difference I can see is that PowerControl likely won't work if I do not have my non-essential loads wired into AC-out-2, because it probably does not look at the ET112 for the current draw of upstream loads. But I also don't see how that matters in a situation where it is impossible, or else very unlikely that even with the MP2's charger drawing as much current as it can, that total load could exceed cutout/service fuse rating (or that of respective RCBOs').

In which case, when I install this thing, I have a bit more freedom as to where to install the MP2. I need only divide my consumer unit into two, install two runs of 10mm² (good enough for 50A) from the consumer unit to AC-in and back from AC-out-1 to the consumer unit to power protected half.

Have I understood all this correctly? Thanks.

Hello all,

I use the battery isolator 120-2 AC to charge redundant batteries (24V, 150Ah each) with an alternator. To ensure the excitation of the alternator, the isolating diodes have this special Energize connection.

According to the datasheet, the Energize is a current-limiting connection for start-up excitation. What does current limiting mean? How much current can flow max.

And does this current only flow to the input connector into the alternator or can the current from Energize also flow to one of the output connectors?

The line to the Energize connector is fused with a 6A fuse. But it keeps blowing out. Therefore the questions.

As an additional note to Victron, please provide more info in the datasheets.

Thanks and greetings

I have the MultiPlus 3000va 12/3000/120.

I'm confused as to where the "AC-OUT2" wires go into the distribution box. I have a 30amp service to my motorhome breaker box. Ill be using the left hand bus only because the box is capable of 50a service.

Do the "AC-OUT2" wires coming from the MultiPlus need to have there own separate bus or sub panel? I'm using the left side of my distribution box bus for the "AC-OUT1" connections, should I use the unused right hand side bus to wire a breaker for my two air conditioner units?

"The "AC-OUT2" can support loads of up to 25A"

Would this mean that I should install a 30 amp breaker on the right hand unused bus coming from the MultiPlus and then two 15 amp breakers going to my air conditioners?

The instruction manual also states that "An earth leakage circuit breaker and fuse rated at max. 32A must be connected in series with AC-out-2."

I dont see anyone using these earth leakage circuit breakers in their RV distribution boxes. I dont see any 32 amp Square D type breakers for sale either that would fit into my box.

Any help or guidance would be greatly appreciated. Thank you!

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I found this in MP-II documentation:

Auxiliary AC output (AC-out-2)
Intended for non-critical loads. Default behaviour only allows AC-out-2 after a 30 second delay when AC input is detected. A Current measurement circuit enables PowerAssist. Override programming for more control of this relay is possible.

Where I can find something about this "override programming"?