More intelligent Generator handling

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petajoule asked Apr 4, '20

More intelligent Generator handling

Victron Multi/Quattro & Generator is a topic from time to time, where the Vics do not accept a genset, problems with stability etc.

True, one significant part of the problem may be that Generator vendors often market/label their products with rather optimistic specs (where you find out that your 5KW genset actually tops out at 3.5KW and similar).

However, after observing (and filming - movie available upon request) the handling of a 3p Genset by a bunch of Vics, one would like to suggest that there is a lot of room for improvement on the side of the Vics.

I would suggest to consider implementing an "adaptive mode" for the genset in the Multis/Quattros. What is that?

The Victrons could start with a load of - say - 1A for the genset and slowly ramp that up until the genset voltage drops significantly (or completely). Either make several of these measurements and then remain under min(measurement1, measurement2, ...) or just one and remain under the "collapse threshold" with a safe margin.

In any case - don't put load on gensets like an on/off switch! Almost no genset can handle this.

https://community.victronenergy.com/questions/8740/can-i-slowly-increase-generator-input-current.html

It would be nice if that could be implemented soon-ish.

Watching our video with the poor genset getting bashed one feels almost "rooting" for the Victrons like "come on guys, you can't be that stubborn" ;-)

battery charging Generator input current

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Answer 1 · 2020-04-04T11:27:56Z

JohnC answered · Apr 04, 2020 at 11:27 AM

Hi @PetaJoule

The feature you suggest already exists. Perhaps not in the exact same form you envisage, but..

"2.1 Dynamic current limiter

(default = disabled)

This feature is intended to reduce load impacts on low-power generators, such as portable inverter technology models. These generators may be unable to respond to sudden load impacts.

By activating the limiter, the PowerAssist® function of the MultiPlus will absorb the change in load and transfer it smoothly to the generator, giving it time to react."

Given that it uses PowerAssist functionality to soft-start things, there's a minimum ac A that it can start with, which shouldn't be of great concern with reasonably matched kit. That level varies with 'Multi' size, so ask if you need that. Without looking it up, it's like ~3A on a 5000VA unit.

Generators can be a pita. Most can be made to work though: https://www.victronenergy.com/live/multiplus_faq

And it's not as though Victron are new to this. From 2007.. https://www.victronenergy.com/upload/documents/VE_Marine_generator_test_RVA_07-jan-2008.pdf

The sinewave distortion an eye-opener (before the days of inverter gennys?).

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petajoule commented · Apr 04, 2020 at 01:19 PM

Of course!

Dynamic current limiter is indeed the feature needed here, but you still have to make an educated guess about the max. load deliverable by the genset.

The suggestion was that the multi should be able (IMHO it has everything it would need for that functionality) to detect that load threshold itself - by ramping up load and observing voltage.

But yeah - in terms of avoiding that on/off switch this is the answer. And actually... shouldn't that also be the answer in the community article I linked? I was somehow blinded by the fact that Victron staff didn't come up with it.

However - one question remains:

Dynamic Current Limiter docs say that Power Assist will support the loads so that generator may be burdened incrementally. What if the "generator burden" is - in fact - charging the battery?

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JohnC ♦ petajoule commented · Apr 04, 2020 at 02:01 PM

PowerAssist is to support loads the genny can't handle alone. It inverts from the batts while doing that.

And if the genny is handling a load and charging too, it's just a matter of reversing the functionality in the circuitry. Can't do both at the same time, but it's the same circuitry, and the reversal either way is seamless.

Setting the max a genny can take is something you do yourself. You just know.. or learn to know.. :)

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