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jbakuwel avatar image
jbakuwel asked

Input Current Limit MultiPlus-II

Hi all,

I am wondering if anyone knows what happens when I:

  • disable PowerAssist (it has to be disabled so the Input Current Limit can be lower than 3.9A for a Multi)
  • set the Input current limit of a MultiPlus to say 2A
  • switch on a 10A load on the AC-out

I'm looking into ways to dynamically adjust the power take from an external power source between "as low as possible (0A would be great, but 1A will do too)" to 20A.

Would the MultiPlus supply 8A from the batteries and 2A from it AC-in in my example above? Or would it trip with an overload?

Jan


Multiplus-IIcurrent limitinput current
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2 Answers
Alexandra avatar image
Alexandra answered ·

@jbakuwel

The lower current limit is affected by the firmware loaded on it.

https://www.victronenergy.com/blog/2018/04/20/multiplus-quattro-inverter-chargers-improved-current-limits/ not sure if you read this article?

https://www.victronenergy.com/live/multiplus_faq#powerassist


If you disable power assist then it will pull sudden loads from the grid source not assist from the battery bank as power assist is designed to do. A small video demonstrating power assist https://www.youtube.com/watch?v=MEF7X1gPPzw

You will only overload if you exceed your battery or inverter capability.

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jbakuwel avatar image
jbakuwel answered ·

Hi @Alexandra,

Thanks for getting back to me. I have read the article. The minimum current limit for the MultiPlus 5KW is 3.9A with PowerAssist enabled. You can go lower with PowerAssist disabled. My use case is a "reverse" PowerAssist: the Multi needs to provide the bulk of the power at all times. Depending on a number of factors, there's also a "bit" of power available from an external power source which I would like to dynamically regulate, if possible between 0 and 30A.

I don't know what happens when you disable PowerAssist, yet have a (limited) power source connected to AC-in. From what I've read and heard in various places the Multi will engage the relay, ie. connect AC-in with AC-out. In other words, the power source on AC-in will power the loads - to the maximum set by the limit. I hope that, despite the fact I have just told the Multi not to assist, it will provide power to AC-out as well to supplement what the limited energy source on AC-in cannot provide.

Jan





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Alexandra avatar image Alexandra ♦ commented ·

@jbakuwel

Are you using virtual switch or other programming? From what i understand from how you are explaining it you are wanting more of an island mode. To use the grid only under certain circumstances?

The purpose of power assist is to keep the inverter switching on the bigger loads instead of using the grid. That is what was demonstrated by the video i linked in the previous reply.

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jbakuwel avatar image jbakuwel Alexandra ♦ commented ·

Hi @Alexandra,

Yes, I understand that. This is indeed an off grid system. If it would work, I could choose to connect the AC-in to an external power source that has variable capacity. With PowerAssist enabled, the minimum is 3.9A (almost 1KW), which is a bit much for that external power source. What I need to know is what happens when PowerAssist is disabled, there is a external power source connected to AC-in, the Input Current Limit is set to lower (or much lower) than the loads that will be on from time to time on the AC-out.

Best regards,
Jan

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