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Multiplus/48/3000 connects to Generator but doesn't charge. DVCC or tail current issue?

Hi All,

I'm running an off-grid system using MultiplusII/48/3000 with a Cerebo GX, MPPT/250/100 VE.Can rev2, SmartShunt 500A all connected with VE.Can. My battery setup is 20x 250A 12v Gel batteries in 48v with 3 battery balancers.

On the Multiplus AC input we have a 7.5Kw generator that we've configured to start when GX relay is turned on. We want to use the generator on cloudy days top up the batteries while briefly running our critical load.

When we start the generator and the Multi accepts the input, we see the system taking over 1000W from the gen to supply load and help charge the batteries alongside the MPPT250/100 as we expect. However, after less than 2 minutes, the load on the generator starts to drop in a very controlled fashion. It appears that either Multi or another device is limiting the generator input for charging, even when the MPPT is clearly still in bulk and the batteries need charging. This makes us very nervous about when bad weather will come and we'll be reliant on the generator charging the batteries.

We have not enabled DVCC yet for this install as we're not entirely confident about its impacts with our setup and running these Gel batteries. We also have issues with the Smartshunt's tail current settings not being able to set the % value below 0.5%. Given we're running over 1000Ah storage capacity, a tail current value of 0.5% is still 50A! We'd need either an Amp value or 0.05% to get to a more normal 5-7A tail current setting. I believe this results in our batteries always showing 100% as soon as the MPPT's start charging in the mornings.

We suspect it may be the tail current setting with battery SOC always being at 100%, but we are unsure this is why the Multi is not using the generator for proper sustained charging along with the MPPT. Perhaps because we're not using DVCC and this will help with global control of all the devices working together?

Attached some pictures showing setup and generator on but not charging. When MPPT is on, it give charge to battery. When MPPT is off, generator still doesnt charge.

Gen with MPPT.jpg
Gen without mppt.jpg
Smartshunt settings.jpg
Multiplus settings 2.png
Multiplus settings 3.png
Multiplus settings 4.png
Multiplus settings 5.png
Multiplus settings 6.png
physical setup.jpg

kmr asked
kmr commented ·

1 Answer

Generator Input on Quattro 2 not working

Hello to everybody,

I am new here and my reason for registration is a problem I can't solve.

Configuration of my system:

Cerbo GX with GX Touch
3x Quattro-II 48/5000
8x Pylontech 3000C

power input from grid on AC in 2
input generator AC in 1
all power out on AC out 1

Everything works fine, running on grid batteries are charged, if grid fails the system switches to batterie.

Now if I start my generator, the system switches AC in 2 off, battery takes over instead of generator.

Generator works fine, voltage is ok, frequency is correct, phases in correct order.

What can be wrong that the input of the generator is not accepted?
Are there any settings to be changed? As far as I understood, generator takeover is the default behaviour?

Any hints are very much appreciated!

Best regards,

Bjoern Clauss asked
Bjoern Clauss answered ·

1 Answer

Why is the multiplus not utilizing a generator fully?

Recently I purchased a small Honda generator with Bluetooth (this allows one to monitor output) to support use of an air conditioner. The generator feeds into the multiplus which then feeds the circuit panel with one breaker dedicated to the air conditioner. The generator is rated to a steady state value of 15A*.

When the batteries are at 100% this works as expected and the generator consistently produces ~1600 VA. This appears to be close to what the air conditioner needs with both the fan and compressor on.

However, when the batteries are as some lower level, say 50%, this doesn't happen in steady state! Initially, yes, the generator produces ~1600 VA. but that doesn't not last too long. In one case it maintained ~1600VA for an initial 10 min or so but then it suddenly reduced to some lower level (~1400 VA) even though the air conditioner was running fully! With insufficient generator output the Multi pulled from the battery to meet the air conditioner demand which I learned after the fact. A very undesirable situation, particularly when the battery is already at a low SOC!!!

In the case where I caught this happening I used the Digital Multi Control Panel to turn the multi to "charge only" for a few seconds and then back to fully on. I found doing so caused the situation to somehow reset and the generator went back to producing ~1600VA temporarily.

Obviously, what is desired (and what the manual suggests) is that the multi itself keeps the generator at maximum output and any extra energy above the current usage is used to recharge the batteries (i.e. when the compressor cycles off).

What is going on here? How do I prevent this behavior going forward? I'd like to be able to trust that the generator is utilized to it's maximum and no power is unnecessarily taken from the battery.

* Note: I am using a Digital Multi Control Panel which is set to a current limit of 16A. After some experimenting I found this value prevents the generator from overloading and shutting off.

** To get around this issue I did consider using the Multi Auxiliary AC output. However, I hesitate to wire this directly to the air conditioner as that would bypass the distribution panel and the 20A breaker protecting the wire to the AC. I don't have space for another box to house a separate breaker.

2022.05.10 MultiPlus configuration.pdf

earl0101 asked
Matthias Lange - DE commented ·

0 Answers

Bug? Quattrtro II (Gen) Algorythum too Aggressive

Hier I think is a Bug! Generator is running @3kW on a Quattro II. Should be 5kW. The genny needs a less radical ramp-up time. If I set the input @10A input and gradually bring it up to 23A all works as designed(5kW)! Set the Quatto II to auto it throws the generator out >20 times and get only 3kW! after sync.

System: 3Ph MP2, RS450/100, Quattro II (Genny) All FW' up to date.

stubbs asked
stubbs edited ·

5 Answers

Can GX generator start/stop feature control AC in of Quattro?

Hello all,

For a setup on a yacht, I want to control the AC in 2 of the Quattro so that during the sunny hours of the day, the shore power does not charge the Quattro. The result is that during the day only my solar panels charge the batteries.

I enabled in the Venus GX the feature generator start/stop, in such a way that the generator starts at 18.00 and stops at 08.00 hrs. I then set AC in 2 in the GX to generator. I am assuming this then controls relay 1 of the GX and switches it on and off based upon the indicated hours.

I then wired relay 1 of the GX to the auxilary relay of the Quattro.

With VE-configure, I added the following assistant to the Quattro:


Will this work? Will the AC in 2 be ignored from 08.00 till 18.00 hrs?

jurjenhoekstra asked
pedro costoya answered ·

7 Answers

Quattro refuses generator when charging with more than 1250W?

Setup: Quattro-II 48/5000/70-50/50 + 3 Pylontech US3000C + Hyundai HY8500LEK (one phase)

Dear community,

we are currently in a no-grid situation, where I need to charge my three Pylontech US3000C with a 8500W Hyundai generator HY8500LEK (Manual and specification:

Charging works, but only when DVCC "maximum charge current" is set to 25A (at ~50V: 1250W)

As I understand, with three US3000C, I should be able to charge with 3x25A = 75A. But when I set the maximum charge current to 30A or higher (on Cerbo GX), charging only works intermittently - 15 second charging, charging breaks off, inverting starts, then a while later, it tries again, same thing...

How to analyze this situation? The generator should support a higher charging rate. Our AC loads are only ~500W, so with 25A/50V charging, the total load to the max 8500W (one phase!) generator is only 1600-1800W.

Is it because the generators AC out is not clean enough for the Quattro II, when running at higher loads? I can provide statistics, if you tell me what is needed.

I am aware of the Victron Generator FAQ, but as we are currently in an emergency situation, I would prefer not to do any firmware changes, which could result in a complete shutdown. No ESS is set up.

Thank you

tobyfw asked
Paul B answered ·

1 Answer

Multiplus II - AC input ramp up time

Recently installed a Multiplus 3000 at a RV of a customer. He had a (small) petrol generator already available. (2800W). However, since this is a rather old unit, it struggles with sudden high loads.

From idle (no load) to a load takes some time to stabilize. The MP however detects it as a instable grid, and shuts down and the process repeats.
(Customer has an auto transfer switch so the AC input of the MP is either grid OR generator)

I have to reduce the DC charger to 20A in order for the MP not to shutdown.

By adding a base load of 300W (Halogen bulb) I was able to get 40A (common trick to stabilize small generators). However, I think it would be able to provide more charging if the charger ramp-up was slower (so the generator has more time to adjust for the load).

On some of our bigger UPSses we have an adjustable ramp-up time: The time which it takes to slowly switchover the load (and not a big drop of the load on the generator).

Is it possible to configure this setting? (Either a configurable timer, of just a toggle box 'enable slow ramp-up' which is like 60sec or so (so smaller generators have sufficient time to stabilize)

djsmiley asked
JohnC commented ·

1 Answer

is there any experiance using 48V diesel or gasoline generators/chargers for ESS ?


i am using 3x Multiplus II 5000 for my ESS.

And i think about adding a fossil fuel based generator as a backup-system.

As my multis have no 2nd AC-input, and i don´t want to change to quattros, i think about installing a 48V DC-Generator, that only charges my batteries.

This should be a simple integration, isn´t it?

This could be configured by "has DC-load", and it should show as negative DC-load in VRM, correct?

I found that there are already a limited number of such 48V DC generators/chargers available on the market, see e.g:

or some cheap chinese untis, which seem to be somehow common for Telecom applications:

So my question is:

Has anybody any experiance with this approach?

Are there any 48V DC generators that have been tested or can be recommended for this approach?

thanks to everybody!

pedaaa asked

0 Answers

Charge my off grid solar battery system with generator

Hey guys,

I have searched but did not find an answer. So hopefully i find one here...

I'm running an offgrid solar battery system with the

Multiplus 48/3000/35 inverter. 230volts

Mppt 150/60 charge controller

Revov lifepo4 100Ah 5.12kv lithium battery.

On cloudy days i want to charge my battery with a generator. It's a genpower GP7000/4

I connected it to the AC in and for about 10 seconds the multiplus switched to charging mode before it returned to inverting mode agaon. After that 1 time it now seems my inverter doesn't pick up the AC IN load

I guess it is a settings issue?

Thank you

jochen-p asked
JohnC answered ·

2 Answers

Generator and Weak AC questions

I own a generator (BXGND6300E diesel with AVR) which like many others is only accepted by my
Multiplus 2 48/5000 if Weak AC is selected in VEConfigure.

I have read the generator FAQ and have experimented with different settings on the Multiplus as well as a stabilizing load (400W construction light) on the generator parallel to the Multiplus connection,
but the output of the generator seems to be of too low quality for the charger.

Here are my questions:

1. With Wéak AC the generator shows a load of 2.800W while the Multiplus charges the battery with only 2.000W.
There is no other load connected to the generator or the Multiplus AC out. That means that 800W disappear somewhere inside the Multiplus. It is also running quite noisy in that configuration.
That cannot be a healthy state for the Multiplus. Is this not detrimental to the inverter / charger?

2. I do not think I can configure the Multiplus to accept the generator output as it is (without Weak AC).
So I want to improve the generator output, might be possible since the generator itself is quite powerful.
To do that however, I must know, what is the problem with the generator voltage / frequency.
Where can I get that information in my Victron system (Cerbo GX, Multiplus 2 48/5000, 2x Pylontech US3000C)?

Thanks in advance,


wnoeth asked
stubbs answered ·

4 Answers

1ph generator in 3ph multiplus II installation possible?

In thread
Johannes Boonstra has given a very detailed answer reagarding a 1 ph Generator into 3ph Quattro installations.

How about Multiplus II? Is the suggested setup also possible in a 1ph generator - 3ph Multiplus II installation?

Thank you for advice.


Michael Timler asked

0 Answers

Cerbo GX Setting Amperage Limit based on Generator

Howdy- I'm setting up an RV install with 2x Multiplus, a Cerbo, pre-existing automatic transfer switch (ATS), and pre-existing 220V Onan genset. Okay- so the transfer switch takes shore (50A service) and generator haven't tested which it favors. So my thoughts are ATS L1 going to one multiplus and ATS L2 going to the other multiplus. What I'm confused about here is if I can setup decently smart amperage limits based on the input. Eg, can I say that for shore I'm at the house and hooked up to a 15 or 20A, but if the generator is on use all the available 45 amps. I know that since the ATS is out of the CAN system (is there any integrated ATS?) it won't know which source is active. But my thought is if the system is kicking the generator on itself, that it would set it to 45A. After the generator goes off, set it back to previous amperage. Is this something that the Cerbo can do or something that I might want to write an MQTT script for? Though- if I recall correctly, since the gen is 5.5KW with 2 lines, the input amperage should be ~22.5 which is close enough to the 20A in this example and on a 50A service or 30A service switching to the genset doesn't make sense. So I'm probably just over thinking this 15/20A service situation but am curious if others have answers.

Myles Best asked
derrick thomas answered ·

4 Answers

AC input connection delay when using a generator


Is there any good way to delay the connetion of a generator to a Multiplus, so that it can warm up for 5 minutes before the AC input connects and start loading the generator?

kjellare asked
Jason - UK answered ·

1 Answer

Trigger Relaise immediately on grid (mains) failure


I have a system - multiplus 24/2000, Cerbo GX. Its a UPS system. Grid is on all the time ( unless it fails .. )

I would like to trigger a relais on the Cerbo immediately when grid power fails, use that as signal for load shedding.
I have been trying to use "generator autostart"

So far, I am getting the "grid lost" alarm

"Auto start functionality" on the Cerbo is on - the conditions are all default.

Am I missing something?

Any hints are highly welcome

Thanks and greetings from cold Colorado


oskaratk asked
Jason - UK answered ·

1 Answer

Water wheel generator with MPPT solar charger?

Hi people of the world!

I would like to connect a brushless generator to a solar MPPT battery charger (BlueSolar 100/20 or 100/30). Would it work? It should brake the water wheel and find the optimum power point, but I never tried that, so I don´t know. To the batteries I would connect an inverter, so that I can use AC and draw energy from the batteries. Do I need a DC load on the controller (like for BlueSolar 100/20) or can I put it after the inverter (AC load)?

Thank you!

luca-cristofori asked
matt1309 answered ·

2 Answers

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