I’m a newbie at this and my system has been running fine for a wile in an off grid spec.
My system is:
Mp2 48/5000/70
MPPT 250/100
Cerbo GX
2 x Pylontec US5000
Hyundai 6.5 kva diesel gen-set with AVR
We’re now getting into winter and I would like to charge the batteries with the gen-set when the sun is out for a few days.
However, when I connect the gen-set I can hear the relay kick in and almost immediately switch off again. Sometimes it stays on for some seconds but cuts out again.
The AC in L1 shows that the gen set is running with the correct voltage and frequency (48.8 to 50 Hz), but the active AC input display shows disconnected.
I’ve tried different settings but to no avail.
Input current limit is set for 14A
AC input 1 set for generator
I’m wanting to start the gen-set manually when I need it to charge the batteries, I don’t need auto/start stop.
Your assistance will be much appreciated.
Thank you
First … try the “Weak AC Input” then he is a little more tolerant with the ‘Tired AC’
But I think that the AVR generator will be the problem. It is not an inverter with a stable frequency.
Reduce your input current even further for testing
Hi @Skydog
What you’re seeing is the instant demand on the genset when it switches in, and it doesn’t have time to react. Then a little offspec power results and the Multi rejects it.
Try ticking ‘Dynamic Current Limiter’, which will allow it to wind up over a few seconds. That alone should fix it, but there’s some other general stuff here… https://www.victronenergy.com/live/multiplus_faq
The WeakAC might help, but the downside is your 70A charge setting will be seriously reduced, maybe even below 50A. It fools with Power Factor too, and can even make loads like a quiet heater fan sound noisy.
So far, I got one step ahead, better that what I did’t have before.
I did what Steffen said and I also fine tuned the gen-set’s Frequency to exactly 50Hz (it was on 48.9 Hz) .
Now what is happening is the MP2 accepts the generator, but only under load. I had a clothes dryer, washing machine and pool pump running simultaneously. See attached pics with and without PV charging.
However, I can’t seem to get it to work with the MP2 power switch on the charge only position. I would want this feature to work.
@JohnC, I will try your suggestion by ticking ‘Dynamic Current Limiter’. Could you please elaborate more on the overlooked settings on the Pylons please? I did look at your link but I’,m not sure what I’m missing, I will look again.
Thanks in advance.
What frequency range have you tuned the multi to?
Unfortunately, an AVR control always oscillates with the frequency when the load changes, as the speed of the generator changes.
It is therefore quite possible that the Multi will disconnect again when a load switches on or off.
It would probably be better if the battery was already a little more discharged so that the charger of the multi could load the generator nicely. Then you would also have a stable load.
If you only use the generator for charging, you could also charge stably on the DC side with an additional 2 kW, for example.
Then the generator would be utilised with 4kw …
So again the question of whether the generator runs on 1-phase or 3-phase.
Not sure about your comment “If you only use the generator for charging, you could also charge stably on the DC side with an additional 2 kW, for example.
Then the generator would be utilised with 4kw …”
You could operate other AC loads with it at the same time … cooker or microwave …
But if it is only used for 1-phase charging, you could work in parallel with the multi with an AC-DC charger that charges the battery directly … without detours through the multi … with the advantage that the AC-DC chargers always charge … regardless of whether the Multi breaks in or not … is a pure consideration
purely as a consideration so that the AVR doesn’t always collapse like this. You could leave the input current limitation so that the generator does not break down too much and still support the battery via DC chargers. Simply configure the DC as a DC charger via a separate shunt and then start with 4kw charging on AC … and DC side
OK, thank you for that Steffen, I will certainly consider it.
However I will fiddle first with the aforementioned settings and so on and see (and learn) where this goes.
Thank you kindly for all your input and effort thus far, much appreciated
@Skydog
Those Pylontech settings you posted were the obvious ones that were incorrectly set. What else have you overlooked, mppt too? Limiting them to the recommended may well be just for failsafe backup, but ignoring them puts you into prayer territory.
I’m curious too why you’d want to have the Multi set to Charge Only?
My own (older) system is virtually identical to yours in spec, except for the genset - same size, different maker. I start it manually too, only when the CCL of the batts is 200A, so I can get the most from it. Once started, an Assistant in the Multi delays acceptance for 1 minute warmup, then it winds up over ~10sec to the full 70A charge, some 3500W. Then I’ll start a load like a dishwasher and it raises further up to the full 20A Input Limit, like 4500W. It’s happy there, and so am I because I can shut it down after an hour or so and won’t have to run it again until the next patch of poor solar and low SOC. That’s my aim, you have one?
@JohnC
I have since changed the parameters of the Pylons as per the settings on the link you sent me, thank you for that. With the MPPT settings, I see it’s controlled by the GX? I cant seem to change them. Any recommendations would be most welcomed.
To answer your question, I would like to set it for charger only (correct me if I’m wrong) so that I could focus all the system energy to charge the batteries in a relatively short amount of time and also to see how long that would take.
To answer your second question about my aim. Currently we don’t have days on end with poor solar but that can change. I need to be ready if that happens so I don’t get caught without a plan when I need one. Please bear in mind that I’m totally new at this, any knowledge I picked up has been for the last six months on many platforms etc. including installing the whole system on my own, so excuse my ignorance if I ask silly questions.
Any suggestions and assistance to fine tune my system would be very much appreciated. I’m happy to share all my settings.
In the meantime I will carry on experimenting with my gen-set as backup until I get to a point where I have a plan.
You won’t need to set Charger Only. Your genset is big enough to make the 70A Charge limit in the Multi the overall restriction. That’s why I mentioned earlier that the WeakAC setting will reduce that even further, so avoid that if you can. Those 2 batteries have a 200A CCL (if not too cold or high SOC), so they can handle all your solar as well as the gen at the same time.
I appreciate you’re fresh to this, but we all were once. Keep asking, and please read the manuals. You’ll have a better system if you understand it. Tis why I suggested a plan…
… Inverter and charger would still be important
