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Offgrid power assist for a 3 phase generator

Hi there

I'm planning on running my woodworking shop off grid. My biggest 3 phase load is 6HP. I could run this with an 18kva generator to cope with the startup current but I'm then only running the generator at part load which, I gather, isn't necessary a good idea for generator longevity.

My thoughts were to use a smaller generator (say 6kva) for motor running and use 3x multiplus as a power assist for starting.

Am I right in thinking I need 12kva power assist? As the multiplus can withstand short term overloads, does this equate to 3x 6kva (or nearest higher equivalent) or is it 3x 2kva (to give 6kva total)?

The rest of the shop will run off solar/wind.

Many thanks, Nick.

nagwood asked
nagwood commented ·

2 Answers

Multiplus 2 AC IN 2 frage


ich habe ein ESS mit einem Multiplus 2 GX.

Laut Bedienungsanleitung gibt es AC IN, AC Out 1 und AC Out 2.

Im Konfigurations Menü lese ich aber was von einem AC IN 2


Mein Gedanke war zusätzlich noch ein Benzin Aggregate anzuschließen.


Ginge das so?


christian-k-1 asked
netrange answered ·

1 Answer

Batteries not charging from generator on AC1 with ESS

Hi guys,

I've got a scenario that I cannot come around by myself and I hope someone might have some suggestions. I've browsed through various forums but none seem to be similar to mine.

More about my system:

I've got a Multiplus 48/3000/35 running ESS through a Venus GX device, a Smartsolar 150/70 MPPT with 12 x 330W canadian solar panels ( 4 x 3s) and 2 x Freedom won E5000 eTower batteries, 10kwh of which 80% usable.

I am connected to a stable grid but we do have outages quite a lot in South Africa so I've connected a 6.5Kva Ellies Diesel silent type generator through a motorized break before make automatic transfer switch with the municipal grid supply to AC1. I've set up the generator stop/start assistant to start the generator only when the batteries are below 20% SOC, as well as with an inverter overload or over temperature alarm. I've also connected the starting circuit of the generator through a NC relay which is energized by Grid supply to keep it open. This means that the Generator stop/start assistant will only be effectively be able to start the generator should grid supply fall away.

This setup works fine but I do however have an issue. When the grid falls away and the assistant starts the generator, the multiplus goes into passthru mode and do not charge the batteries, even when no PV is available. This is only with ESS enabled.

Is there a way, through settings, for a Multiplus to detect loss of grid supply and charge the batteries from the excess power available from the generator? Current limit is set to 12Amps on AC1 and this morning, during an outage, the generator was running with a 3 Amp load on Passthru while it could have charged the batteries with the surplus. I guess the ESS assistant should be able to detect when the Generator start/stop assistant is actively running the generator and change the ESS charging conditions? Technically AC1 will be the effective input for Mains as well as generator, unlike the AC1/AC2 in the Quattro's but this can be distinguished via software with the active assistants, am I right?

I'm not sure if I missed a setting somewhere seeing that I've tried a lot of different settings but cannot seems to figure it out.

This the ESS assistant cannot detect generator operation through AC1, maybe this might be reserved as a future option when both ESS and generator start/stop assistant are being used.

czauto asked
Juha Tuomala commented ·

3 Answers

MultiPlus II disconnects from generator on high inrush

I'm running into an issue with my MultiPlus II 48V 3000VA 120V where it disconnects from my small inverter generator when using a high-inrush device.


This is off-grid, and I've got a small inverter generator (2kW peak, 1600W constant) that I use intermittently to keep the batteries charged. AC input current limit set to 13.3A (1600W) and charge current limit set to 23A (~1300W). Dynamic current limiter is enabled. UPS function is enabled. Power Assisst is enabled with default boost factor 2. Works great for most stuff.

I have a professional photography studio strobe power pack that I want to run off the MultiPlus II. This is basically a big capacitor. Take a picture and it dumps the power from the capacitor into the strobes and then recharges the capacitor for 1 to 2 seconds. So it's got high in-rush current on each recycle. It's nominally a 15A device, although it might spike higher. Works great on just the inverter when the generator is off. The generator by itself can also power the strobe power pack mostly okay. (There is voltage sag on recycle, but it never trips the generator overload protect.)

The Problem

I get frequent AC input disconnects when running the generator for battery charging while also using the strobe. The generator overload protection never trips, but the MultiPlus II disconnects from AC input. I'm pretty sure the generator voltage is dropping below min threshold due to sudden demand. After disconnect, voltage comes back up and the MultiPlus II syncs again. So I don't have to do anything and I never lose output AC. But it's an annoyance that I'd like to correct if possible.

A bigger generator isn't really feasible. I considered trying a soft start device for the power pack, but I don't think it will work. (The power pack has a baseline 300-400W power draw even when not recycling, because it's also powering modeling lights that are on constantly. My understanding is that this would prevent the soft start from being effective.)

The Question

Are there settings on the MultiPlus II that I could try? Would adjusting the boost factor make power assist more responsive to these large demand spikes? What would be a safe range of boost factor values to try?

I may also try turning down the input current limit and/or the battery charge current a bit to leave more generator power headroom. But I don't want to significantly increase the generator time needed to recharge my batteries.

steve-atwell asked
steve-atwell commented ·

3 Answers

Display external battery charging as Genset

I have 3 phase Multiplus II 5000 system with gerbo gx and lynx distributor + lynx shunt. PV is generated from MicroInverters. I have grid meter ET340 and also extra ET340 for solar production.

I want to charge my batterys from my car V2L adapter if needed. To display that correctly as genset I could find only one option. To buy one more energy meter ET112 and add that between car V2L and charger 220v input (this 220 line is totaly seaprated from in house 220v wiring). And configure that as Genset meter. Problem is that most of the time this ET112 does not have any 220v connected to it.

Then charger DC output should be connected to lynx distributor otherwise lynx shunt can not show correct soc value.

I could then also use one phase gas generator to load the battery in emergency.

nuxland asked
nuxland edited ·

0 Answers

Which generators are fully compatible?
I want to build a photovoltaic system for my home similar to the following (I will probably use EasySolar II instead of Multiplus II+SmartSolar MPPT+CCGX):

Which generators are fully compatible?
Someone has already used the Black & Decker BXGND5300E and / or BXGND6300E?
Someone has already used PRAMAC PMD5000s ?
I want to use the generator only for the time necessary to recharge the battery (2-5 hours) when the public grid is not available and solar energy is insufficient (I could also disconnect all non-essential domestic loads, if necessary to facilitate the operation)
I believe it is important that Victron publish a list of fully compatible generators for this type of application, without delegating the responsibility to local dealers.

francesco-marzulli asked
markus commented ·

5 Answers

RCD Typ B am Ein- und Ausgang des Multiplus nötig?

Ist am Ein- bzw. Ausgang des Multiplus ein RCD Typ B (Allstromsensitiv) nötig? Mindestens Typ A am Ausgang ist klar. Anschluss des MP netzparallel mit wichtigen Verbrauchern am Ausgang.

An einem Wechselrichter ist ja grundsätzlich ein Schutz nötig, falls hier ein nicht sinusförmiger Fehlerstrom auftritt - es liegt dort ja ein Gleichstrom vom PV-Sting bzw. vom Akku an.

Hat der Multiplus II einen entsprechenden Schutz bereits eingebaut oder ist der hier bauartbedingt nicht nötig (evtl. weil die Batteriespannung nur 48V beträgt oder weil ein gewickelter Trafo genutzt wird der kein AC durchlässt?)

Wenn nötig müsste ein RCD Typ B ja am Ein- Und Ausgang angeschlossen werden, da in beide Richtungen eingespeist wird und dort Verbraucher (über einen RCD Typ A) angeschlossen sind.

behl asked
juergenal commented ·

2 Answers

Generators compatible with Fronius grid tied inverters.

We have a Fronius grid tied inverter connected to the output of a Quattro. Fronius grid tied inverters have a shutdown facility which utilises frequency shifting the ac by 1 Hz.

Suppose we have an ESS with a Fronius, Quattro and a generator. If the generator kicks in and the frequency is not exactly 50 Hz, the Quattro will frequency-track it and in doing so inadvertently shut off the Fronius grid-tied inverter.

Do we have to purchase a super-stable generator with exact 50 Hz frequency in order to prevent conflicts between the frequency of the generator and the grid-tied inverter?

Barry Clark asked

0 Answers

Charging by means of sinewave inverter connected to Quattro AC-IN-1 (generator)

We have a vehicle (van) with a 12 V system and 4 kVA Quattro. We wish to supplement the 48 V (Pylontech) battery charge, when driving the vehicle, by charging the battery from the vehicle 12 V supply.

We have tried two different 1 kW 12 V to 230 V sine wave static inverters connected to AC-IN-1 (the generator supply to the Quattro). Despite adjusting the Quattro input current limit to minimum (4 A), shortly after the inverter supply to the Quattro is enabled the 1 kW inverter is destroyed. The output H-bridge at the output of the 1 kW inverter becomes damaged shorting the high-voltage supply in the inverter.

We believe that the Quattro inverter is essentially back-driving the inverter mains output (once the relay clicks in) and the phase alignment is lost as soon as the Quattro draws current from AC-IN-1 and loads up the 1 kW inverter.

Has anyone out there had any good experiences with charging from an inverter connected to the AC-IN-1 connection to the Quattro?

A potentially safer charging option may be utilising a battery-to-battery charger to charge the 48 V battery more directly using 48 Vdc. Unfortunately, Victron does not produce a 12 V-to-48 V B2B charger so we are considering Sterling Power unit. The Sterling B2B does not have a communications bus and is unable to communicate with the CCGX or Quattro. Therefore, we will effectively be charging blindly.

Would this possibly cause a charging conflict or race conditions with the Quattro when the B2B charger is on if the BMS is unaware that there is another charge source connected?

There’s also a mention of having to set the float voltage of secondary chargers slightly higher than the primary master charger in order to provide a clear cut off and resolve charging conflicts between the Quattro and the B2B charger. It is unclear if the B2B has a means of adjustment.

Barry Clark asked
Alexandra commented ·

0 Answers

ESS 3-Phasen Multiplus mit zusätzlichem Multiplus als Ladegerät

Hallo, ich plane ein ESS mit 3 Multiplus II 5000 als 3-Phasen-Sytem. Anlagenschema.pdf

Bei Netzausfall und fehlender Solarleistung soll der Pylontech-Akku über Generator nachgeladen werden können. Wegen des Gridcodes fällt die Möglichkeit der Generatoreinspeisung über Umschalter am AC-IN weg. Deswegen würde ich einen zusätzlichen Multiplus einbauen, der dann durch den Generator gespeist wird und ausschließlich zum Laden genutzt wird.

Im Grunde wäre hier der Einsatz von 3 Quattros im 3-Phasen-System ideal da hier der Generator über den 2. AC-IN eingespeist werden könnte, die Möglichkeit entfällt aber wegen des noch nicht vorhandenen Zertifikats für den NA-Schutz...

Nun ist meine Frage, ob der Cerbo GX den zusätzlichen Multiplus erkennt und ordentlich darstellt?

Oder kann ein GX-Gerät immer nur ein System darstellen, also entweder die 3 Multiplus 5000 ODER das Multiplus 2000?

maworxx asked
andreasbrb commented ·

1 Answer

Quattro II 48v 5kva won't switch Active AC input to genset in AC1

Quattro II 48v 5kva here with European grid connection and old Perkings 12kva diesel genset. I'm trying out features for their feasibility.

Genset has electric start and running signals from its harness, but I'm starting it manually so far as I don't have the harness panel side with its instrumentation. However it gives steady 230V/50Hz in three phases, I'm using only one so far.

I've read quite many Quattro and genset threads and doc pages here. At least the following has been done:


- genset in AC1 input

- grid in AC2 input

- System setup -> AC input 1 = generator

- System setup -> AC input 2 = grid

- System setup -> Monitor for grid failure = disabled

- Generator start/stop -> Auto start = off

- Generator start/stop -> Settings -> Detect genset at AC input = off

- I/O -> Digital inputs: None has "Generator" as input value.

- Relays -> Relay 1 = Generator start/stop, not used yet.


- General -> Dynamic current limiter = On

- Grid -> LOM (loss of mains) detection -> AC1 input = disabled

- Charger -> Weak AC input = on

- Assistants -> ESS loaded

When the genset starts, multimeter shows good voltage and frequence in AC1 terminals, as well in Quattro's remote console top level's Quattro menu AC-in L1 numbers. But that also shows 0W and 0A current.

With these settings, Quattro detects the genset in AC1 since it drops the grid from AC2 and remote console shows in Active AC input: "Disconnected". When I turn genset off, it changes back to grid in AC2, then Active AC Input says again "AC IN2".

So, Quattro sees getset power in AC1, but doesn't accept it to passthrough nor for charger.

Maybe I should try to feed grid juice into AC1 as "genset power" and see does it accept that or is this a settings problem. Not sure would there be any neutral line issues, would assume that those are galvanically isolated inputs and that doesn't matter.

Both AC1 and AC2 inputs do work, as I just recently moved grid to AC1 as suggested.

Anyway, I'm inclined that this is a settings issue, can anyone give a hint what might cause it and what to try next?

I can't switch off the "UPS Fuction" from Grid -> Transfer switch as it doesn't exist anymore in current versions. Documentation should be versioned and modifyed once these changes are done, some people might still use older versions and need the old docs. Current situation is confusing.



Juha Tuomala asked
Juha Tuomala commented ·

2 Answers

Discharge floor generator autostart

When i set my discharge floor on 50%

And the geneator autostart stop on 0%- 100%.

Will the 0% actual be 50% or would i completly discharge my battery bank to 0%?

marc-heide asked
marc-heide answered ·

3 Answers

Multiplus II/Quattro II: State of (co-)generator support in ESS mode?

@mvader (Victron Energy)

@Johannes Boonstra (Victron Energy Staff)

Customers are waiting for months now to have (co-)generator support in Multiplus II/Quattro II ESS mode. Especially with the new geopolitical situation (Russia) customers demand co-generator or backup generator support in stationary/grid tied installations.

What is the current state? When will generator support be available in ESS mode?

renne asked
404 commented ·

6 Answers

Generator AC-IN and PV Inverter on AC-Out (Zero feed protection)

Hi community,

I want to take some safety and be sure that my generator will never get feed-in from the PV inverter, so my flow is like this:

  • if the grid has been lost and batteries go near 20%, I will start the generator (a small gasoline generator, without automation functions)
  • then on CerboGX, change AcSource to Generator (there is no way to change using automation, over Modbus, unfortunately)
  • the change of ac-source-type will trigger an automated workflow that will change a contactor to enable the generator and also change ac-in Amps to what the generator can make (24A) (Modbus /Ac/ActiveIn/CurrentLimit)
  • Multiplus will soak as much energy from the generator as possible from AC-In + PV solar (Fronius) on ac-out
    • while batteries are low, and still in bulk is It safe to run PV solar (Fronius) with the generator on ac-in? is it possible to get feed-in by multi into the generator?
  • The batteries will reach some "end" goal which is 80%, my plan is to disable the PV inverter using `/PvInverter/Disable` Modbus, this will give me an opportunity to PowerAssist OR change the contactor that goes to a generator

As for now, my main concern is safety and not burning generators with feed-in, all other automation of how to get back to the grid could be automated later.

Thanks for the help!

Fedya Skitsko asked
Fedya Skitsko edited ·

2 Answers

how connect genset ATS to quattro II with cerbo gx

Hey need help, Anyone knows how to connect genset deawoo ( to input 2 in quattro II system ( 3 fase).

Do i need specific 5 pin cable to ATS and connect to cerbo gx for start/ stop comunication ??

mk1 asked
cristimv answered ·

3 Answers

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