I’m off grid and am struggling to charge my x12 48v AGM batteries to float, via the Victron multi I have, via a 4.5kw diesel generator.
The multi is a 48/3000/35-50 with a maximum output of 7.5A 1500W.
The volts come up, but the 7.5A output from the multi is just not getting them to float.
I’ve been thinking about a 48v charger attached to the terminals inside the multi, connected directly to the generator, will this work ? ???
What do other off griders do ??
Ideas greatly received?
You should have 35a charging power.
If I go over 7.5A on the generator current setting, it shuts down and restarts???
Ok, so its 7.5 amps on the AC side, if your heater is off you should get 35 amps charge current
Nope! 7.5A ???
If I set the generator current setting to 8A it turns itself off.
I wish I was getting 35A charge in to the batteries, alas not…… 7.5 or nothing.
How do I achieve 35A current setting and out put ??
Pls post all multiplus settings, ofc it can charge with 35amps if all settings are correct and no ac load present.
The generator should deliver much more then 7,5amps if its really a 4.5kw type.
What is your ac voltage, 120 or 230 ?
Is the generator single phase, split phase or 3 phase ?
I’ve had a similar issue with a much smaller off-grid system (gel batteries) and using a petrol generator. These charts might be of interest.
Another chart:
charging is more effective at lower temperatures.
Pass through will work, but only when multi is set to charger only.
When I set multi to on, it limits me to 7.5 A
Settings ?
The guys at midsummer solar have looked over my system online, they’ve done the setting for me.
Please elaborate. Does it stop? Switch off power? Or rejected by the Multi?
That’s a 240V gen, so 7.5A is 1800W. Your Multi can charge at 35A (at battery V, let’s say 50V, that’s 1750W. So really it’s maxed out for charge.
No point mucking with ‘Charge only’ and suchlike, leave it switched ON, then the gen can serve loads too at the same time.
I read your batts as being 690Ah @ 48V, is that right? A good design point for AGM’s would be a tenth of that, so ~70A. 48V chargers are fairly scarce, and another Multiplus would be competitive, Say a larger 5000/70 (the 70 means Charge Amps) or an additional one like you already have paralleled in (get the EXACT same one to parallel). The bonus is more inverter capacity.
But first work out why the genset is gagging at more than 7.5A output. Watch the power specs while it’s running for clues. If it’s getting rejected, see here… MultiPlus Generator FAQ [Victron Energy]
Hi,
It clunks inside and stops the AC from entertaining the multi.
Then, when I reduce the amps down to 7.5 it allows AC to flow again.
The guys at midsummer energy tell me that he multi will only take a max of 1600w input.
Ok, so now we know that they don’t know…
Its a 3000 watt multiplus, so it will take “at least” 3000 w, not regarding the 50a transfer capacity.
I was hoping I could leave the multi switched to on, it accepts a 35A charge, and not a pathetic 7.5A!!
Also, I’d like it to be ON, and then when my usage goes over the multi 3kw, the generator kicks in and passes through its 4.5kw.
Frustrated at I have to put it on charge only to get pass through.
So yesterday, we had the washing machine on, drawing 1900w, switched to on, it took 1500 from the generator and 400 from the batteries.
I’d like it to take all 1900 from the generators, leaving the batteries draw free.
Just trying to get advice from anyone Victron is like try to blood out of a stone !!
Do you have a triple phase generator that supplies 3x 1500w @240v per phase ?
I already asked yesterday, but you always come again with your problems without answering questions or changing anything.
Maybe its best to close this thread.
I’m sorry, no just a single generator.
Please be patient with me, I’m here because I’m at the end of my teather.
I’m also dyslexic
It’s a Hyundai dhy6000se.
The guys at midsummer energy have told me that the problem is a dirty waveform from the generator, that’s why it won’t go over 7.5A.
Any ideas on the pass through not working when the inverter is on ?
Thank you
All help most appreciated
The Hyundai is a good and simple generator, good for 23 Amps.
First of all check if you have firmware version 552 on your multiplus, this version has less problems connecting to generators.
Check that the setting for weak ac is off.
With the multiplus off and programmed for 15Amps start the generator and connect it to a 1000-2000w heater turned on max heat.
Wait until the genny turns regularly, then switch on the multiplus.
This worked out the last few times.
a 4.5kVA generator should be good for 15A continuous at 240v. (4500 *0.8/240) this is the adjustment for power factor. (can correct this upwards if 6kVA).
this should give you a theoretical 75A at 48v - but the multi will limit this to 35A.
If you have a multiplus2: look in the grid tab of VE-configure (on a lap top connected with a Mk3) You will see a protection log - this will give the reason for the generator disconnecting under the higher load. AC input current should be set to 15A, and the battery charge current (charger tab) can be configured to 20 - 30A. This leaves plenty of power - or should do - from the generator to run the loads.
Most likely, the disconnect will be due to either an under-voltage or under frequency event. This is why it is important to look at the disconnect log. Either way, the problem probably lies with the generator.
