geomz avatar image
geomz asked

AC Input limit weirdness


Quattro 120v/5000/24v running ESS (custom grid code).

10 Kw LiFe storage

7 Kw genset

Variable shore power options.

When AC input limit is 25A or greater, everything works as expected, with loads running off incoming AC, up to the limit, and any difference coming from batteries, until SOC limit. Perfect.

When it’s anything less than ~25A, it seems, the Quattro loses its mind and basically ignores that setting, or goes bonkers switching back and forth and back again between the battery and whatever the input source —often to the detriment of the input source.

Example 1:

Using a generator, setting the input limit below 25A essentially causes the generator to detect a fault on the line and eventually shutdown —right before constantly oscillating up and down trying to keep up with the inverter.

Initially, I just ignored this issue and wrote it off as a “weird” compatibility issue between an inverter genset and the Quattro. There are copious posts about “syncing” issues with inverter generators and these inverters.

Example 2:

A 20A 120v “mooch docking” option was made available (instead of a generator). This was intended to act as a constant drip of AC, at a very low draw, with the smart Victron inverter in between handling the balance.

Set input limit to 10A.

Utterly ignored. Everything was coming in from the “shore” plug, regardless. But, at least it was stable in its ignoring the limit.

Then, I figured out that SOC was below set-limit, so that made sense. It was essentially running in pass-thru mode. So, I adjusted the SOC limit to well below battery’s current SOC. This should allow it to make up any deficit from the batteries (which had plenty of capacity remaining).

That’s when things got even more weird. Being allowed to actually draw from the battery caused the same ping-pong effect I described in example one above, with the Quattro constantly swinging wildly on input power and battery draw, and then eventually it fully exceed not just the 10A limit I set, but the full 20A limit of the plug, and blew the breaker.

So, I’m confused as to what to expect from that input limit. It seems to be essentially worthless below 25A —even though the UI very clearly lets one set it that low.

And not only that, but it seems to make things considerably worse for the input line, whether that’s a genset or (otherwise stable voltage) input from shore power.

ESSGeneratorcurrent limitinput currentshorepower
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1 Answer
JohnC avatar image
JohnC answered ·

Hi @Geomz

It seems you have a mobile application, yet still using ESS. You may not be aware, but this is clearly against recommendations for ESS use, and can probably explain all the 'weirdness' you see. It's known to push'n'pull at the grid, which is usually an ocean of buffer, but against a little inverter genset is asking for trouble, even damage. There are very few (obscure) reasons that it might be suggested for such use, but I still see it recommended loosely, even here.

I'd uninstall it completely.

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