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rbreding avatar image
rbreding asked

Multiplus 12/2000 Shuts down when using AC on Generator

Preface: AC worked fine previously on 2000w and 3500w generator.

Installed Multiplus 12/2000-80 with the intention of using the inverter for small AC loads etc (no intention of running roof AC on the inverter). Testing the unit today on Generator and it kept faulting instantly due to low battery and "ripple" when the AC compressor kicks on. Generators both set normal running with ECO off. Initially thought that the 2000w generator wasn't behaving properly and tested with the 3500w with the same result. Searched for answers to why my settings weren't working. Reset the Multiplus to defaults to test from baseline. Tried the following:


Current limit of 30a-50a with the same result.
Enabling/disabling current limiter same result.
DC low input set at default of 9.3v
Disabled the charger


Watching the voltage on the BMV it never dips and watching the Multiplus on VE.direct doesn't show the voltage dipping either. What baffles me is why the unit isn't allowing the current to pass right through it? I am not even hearing the generator get hit but the amp draw. I also tested the heat strip in the AC unit as another high amp draw and it works fine. Draws about 1500w and is passed through from the generator through the multiplus just fine. AC unit is the problem. Wiring is 2/0 from the busbar to the batteries (about 5') and 1/0 from busbar to Multiplus (2'). I also eliminated the breaker in case it was weak with the same result.....frustrated.

Any thoughts as to where I am going wrong here ?

Multiplus-II
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coltarkdm avatar image coltarkdm commented ·

Have you tried disconnecting the generator and plugging into shore power? Divide and conquer!

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rbreding avatar image rbreding coltarkdm commented ·

As an update I brought the trailer home from the storage lot. Hooked it up to mains from house and the A/C started up just fine. Multiplus didn't even click.


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JohnC answered ·

Hi @rbreding

You're likely experiencing spikes from the ac load, which may not be visible in the reporting. And the gennies used standalone may be able to deal with that. Usually inverter types will react by interrupting supply, and may revert to normal when the spike passes.

But the Multi will see it, though it may not say so. Usually you'll hear a relay click when it does this.

Presuming you have access to VEConfig, and your supply is 230V ac..

In the 'General' tab, set your 'AC input current limit' to something your genny can handle, say 5A for the 2000W unit. And in the 'Inverter' tab ensure that 'Power Assist' is enabled. I think 2.0 is the default boost factor, but you might experiment with higher.

You could leave the charger enabled, which uses the same circuitry as the inverter, and even a little 'surface charge' in the batts might help ride the spike if small batts are an issue.

If all that fails, there's this: https://www.victronenergy.com/live/multiplus_faq



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rbreding avatar image rbreding commented ·

As an update:

I do have VECONFIG and suppli is 120v AC

Tested today on house mains shore and everything seemed to work fine.

Both generators are inverter tested with ECO off.


I have changed the powerassist factor to 1.0 as a test with the same result on generator. Disabled powerassist again with same result.

Of note VEconfig reports in the "NS Protection Log" an event each time the multiplus shuts down:

Still testing various settings but something in the software is not jiving with the generators. Trying other settings to see.

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rbreding avatar image rbreding rbreding commented ·

When disabling the current limiter I get this over frequency and under voltage.


Listening to the generator when the A/C hits before the multiplus shuts down (albiet instantly) I barely hear the generator even complain.

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rbreding avatar image
rbreding answered ·

More testing:
Started the A/C while on mains....ran it for a minute...then pulled the plug. Inverter took over an A/C kept running. Plugged it into the generator and after the multiplus synched up it switched the load to the generator and kept humming along. A/C cycled the compressor off by itself. When the compressor kicked back on the Multiplus did its shutdown again. NS Protection log showed "over frequency" again.

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JohnC avatar image JohnC ♦ commented ·

Maybe you're making progress, I hope so. I've not seen the Hz issue before, and I guess you're using 60Hz kit. If you're unaware, there's a setting in VEConfig to 'Accept wide input frequency range' (up to 65Hz).

Or maybe you're exceeding that even, with some dynamic in your system?

Inverter gennies would normally easily comply, but they're not tolerant of being pushed to their limits. Maybe sneak-up on the issue to see where those limits really are?


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