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multiplus in parallel

Slow charging on Shore Power from Multiplus with Lynx BMS and Victron Smart Batteries

System is Victron Batteries, Lynx BMS, Cerbo GX and dual 24v 3kva Multiplusses. The batteries are 4 330AH 12V batteries in two strings of 2 for a 24v nominal voltage.

This is on a boat with a solar array and connected to shore power.

We drew the batteries down to about %75 SOC before connecting shore power. While connected to shore power the solar was not being used at all. So we installed ESS onto the Multipluses following advice.

Now when connected to shore power, the Solar produces its max energy (it seems) and the Multiplus is inverting and charging as necessary.

But at night. the Multiplus charges VERY slow. Took something like 12 hours to put in 4kwh which could have safely been done in 2 hours?!

For example, nothing from PV, input limit from shore power set at 18A (2kw) and the battery at a %75 SoC the Multiplus only charges at a few hundred watts, like 200w. This took forever to bring the battery back up to %100. The Multiplus shows "absorption" light as on.

The Lynx BMS has CVL set at 27v and that's the voltage so I think the batteries are maybe at 27v and so there's not much current flowing.

The batteries didn't get down to the %70 threshold set in the Lynx BMS so it didn't start a "new cycle".

So, I guess I understand what is happening, I'm just not sure I like it. I would have hopped the batteries would be charged at 1500w or some reasonable percentage of the shore power current limit unit they were near full.

Maybe I should set the threshold in the BMS to %95?

I do like the idea of fast charging to %95 then trickling from there.

sailing-cat asked
Stefanie (Victron Energy Staff) commented ·

1 Answer

removing GX from Multi5

Hi all,

I have a multi II GX 5kva 48v. I am wanting to expand it and i have the opportunity to get my friends unit (purchased at the same time) which is the exact same as mine.

I am wanting to run them in parallel, and from what I understand, I can only have the 1 GX unit.

My friend is replacing his unit with a 10KVA unit, which does not have a GX.

Is it possible to remove the GX from his 5KVA unit, and connect it to his replacement 10KVA unit? (ignoring the physical mounting if that's an issue. I mean specifically electronically and in terms of it actually working and functioning as it should) and then I can use his old unit as a non GX unit? in parallel with mine.



jbates5873 asked
vintdiesel edited ·

1 Answer

Parallel Multiplus II ground relay Max current

I would like to use 3 Multiplus II 48/3000 120V wired in parallel in my vehicule for educational purpose and public demonstrations. As I understood, the neutral to earth bonding should only be made at one point in the system. This means only one Multiplus will switch its ground relay, the others (slaves) will be disabled. Is that correct?

Since this protective bonding must handle a default current corresponding to the total installed inverter power, in my case, the internal relay should handle continuously :3x3000VA/120V = 75A.

The maximum number of devices in parallel specified in the datasheet is 6, so in reality one ground relay may handle up to 150A...

Can you confirm that the internal ground relay supports these currents?

Thank you for a helpful answer.

Best regards


offgridgirl asked

0 Answers

second multiplus et delestage


J’envisage l’achat d’un second multiples 48v / 1600 car ma puissance est trop limitée dans mon habitat

Mon matériel est actuellement le suivant

3 kwc de panneaux

1 multiplus1 48-1600

2 pilontek 3600

1 Mppt victron

Cerbo GX

L’ajout d’un second multiplus nécessitera t’il des modifier au niveau de la config du cerbo GX ?

J’aimerais pouvoir délester ma surproduction vers un cumulus électrique, du genre quand mes batteries dépassent 80% de charge

Cela est il possible via le Cerbo, et comment ?


christian54 asked
larsea-dk answered ·

2 Answers

2 x Multiplus 2 48/3000 (parallel on phase 1) in ESS: grid setpoint not reached


I am using 2 x Multiplus 2 48/3000 (parallel on phase 1) in an ESS configuration with a Pylontech Battery US2000b+ (9.6kwh total) and a Venus device with EM24DIN. There also is a Fronius Symo 15-M AC coupled inverter with 10kwp PV connected.

All this in Germany on a 3Phase grid ("Schieflast" is avoided by other measures).

The second Multiplus was only installed yesterday, since then I observe that the grid-setpoint is never reached, there is, especially on battery, always a much greater consumption from the grid than set.

Grid Setpoint is set to 10W, true average consumption from the grid is almost 200W all through the night. As I stated: this is only true since the installation of the second multi.

If I adjust the setpoint to -200W, consumption drops but as soon as the solar kicks in during daytime I am exporting more than I want.

What could be the reason?

Thank you very much!


jfleissner asked
harry4516 edited ·

4 Answers

GX or not GX

I'm planning to install a new system with a multiplus-II 5000 but I think that power will be not enough within some time (in a 2 years time frame). I'm planning to pass to a parallel configuration in two years. I will be able to add additional PV modules and batteries (Pylontech) and use more power and also to have a level of redundancy

Considering that is possible to have only a GX device what do you think is the better option:

1. Install now a multiplus-II GX now and then install a second multiplus-II GX, disabling the GX part

2. Install now a Multiplus-II and a Cerbu GX and the install another Multiplus-II

3. Install now a Multiplus-II GX and then, in parallel a Multiplus-II NO-GX

4. Redundancy is not required, use a Multiplus 8k or 10k now and a Cerbu GX and upgrade only batteries and PV modules


Kind Regards!


blackstar asked
kevgermany commented ·

5 Answers

one or two dongles for a parallel setup?

if i have two multiplus-II 3000kV [120VAC] set up in parallel [for a split-phase 120/240] and they are connected via the VE.bus. do i need one or two smart dongles?

as a secondary question does victron have or planning on making a virtual assembly simulator. something that lets you drag and drop components on to a 'work area' and wire them up to see how/if they will work together? that would be able to answer a lot of the questions brought up on this forum

rustythorn asked
snoobler answered ·

1 Answer

Running water heater/ washing machine or Air con off batteries ?

I'm trying to use my water heater/washing machine/air-conditioning when not connected to shore power. Previous owner had a switch that combined both breaker boxes together so that when not connected to shore power it will run. But now it's just trips

I've recently added Four 330ah life-po4

2500w solar panels

Two 12/2000 80/30 multiplus in parallel

So it should have enough power to run off the batteries but keeps tripping the breaker

I've even tried to add assistance via main relay to turn on at 99% SOC and off at 94% SOC

It would work for a few minutes but ultimately it trips

Can someone tell me what am I doing wrong?

maxtosea asked
snoobler commented ·

3 Answers

Multiplus Compact led indication codes

I'm trying to find led codes for Multiplus Compact.
The manaul shows only basic ones, the Victron Tool app doesn't cover Multplus Compact at all.

One of my two Multi Compacts working in parallel shows blinking both red and green led, what does it mean ?

Philip asked
kevgermany commented ·

3 Answers

macOS VictronConnect can't connect over MK3-USB/VE.Bus to Parallel Multipluses.

Situation: Initial setup of Dual Multiplus situation. Everything appears working, but no ability to communicate with Multipluses.

1. The MK3-USB was loaned to a friend who had no trouble using it. macOS shows it in the USB bus tree. Running the latest Ventura version of MacOS.

2. The Multipluses are reasonably late model, running 27xxx413 and 27xxx481 versions. They are giving different LED flashes but according to manual these are not VE.BUS errors. (no opposition flash to the inverter light, which is solid.)

3. The Cables connecting are highly rated Cat 6 cables, premade. Everything appears correct.

How to debug?

The VictronConnect app has two tabs, Bluetooth and VRM. Both of these work. When the MK3-USB is connected should another tab appear with the multiplusses? Or is there something that needs to be done in the app?

sailing-cat asked
sailing-cat commented ·

1 Answer

Parallel Multiplus Master failure at end of scheduled charge

Multiplus II dual parallel 48/5000/70 with Pylontech battery bank. See for setup details.

The system has been working fine up to now, but in the last few nights I have encountered a strange anomaly at the end of the ESS scheduled charge period - luckily I have been there to catch it.

As soon as the charge ends the master of the pair simply stops inverting and the second unit starts outputting too much current, such that the grid feed-in goes up to around ~600-700w and sticks there!

Using a clamp meter I can see that NO current is flowing on the DC input to the master, current is being consumed ONLY by the second unit.

The system does not report any error condition!

Rebooting the Cerbo does nothing, the only way to fix seems to be powering cycling the inverters (via virtual switch), at which point sanity is restored and everything works fine again.

I have the latest firmware for the MP-II's (501) and latest Cerbo (v2.93) update. I have previously tried the beta firmware (v3.0~18) and this also exhibits this failure. I checked and when I reverted to v2.93 the MK3 firmware was reported as reverted by the Cerbo to 212.

Is this a hardware failure requiring an RMA, or a result of the recent v2.93 update, or as a result of swapping to and back from beta firmware, or some other configuration issue or aspect I wasn't aware of?

Thanks, Paul.




Paul Beskeen asked
Paul Beskeen answered ·

3 Answers

Multiplus2 in parallel, so can I use AC2 for different things?

Dear All

I have two Mulitplus2 in parallel (5000VA x 2) that is supplying 230V to my DB.

Only using AC1out but AC2out is empty on both.

My question :

  1. Is it possible to connect different loads on the AC2out for each machine or must the loads be equal all the time (i.e. I have to parallel connect the AC2 to the same load). (I guess the one machine will then see a higher load all the time compared to the other?)

The idea behind this is to operate the boiler (CV) when SOC is above a set point and turn on the circulation pump with the other MP2 when temp is below XYZ (Using AC2 as a relay function).

If you have done something similar (switching on and off loads, depending on time, weather, etc), what did you use to achieve this (i.e. Node-red with relay contactor, Using GXcerbo to trigger, etc.) Please over explain with lots of pictures :) or a link to a discussion/solution will be greatly appreciated.

groningen asked
marekp answered ·

1 Answer

Imbalance when running two MultiPlus-IIs in parallel

Hello colleagues! I need your help. I will be glad if the Victron staff can answer me, as this is important and now it is urgent. I also hope that the information below will be useful to other installers. I have installed dozens of Victron Energy systems, including three-phase (with three units) and single-phase (with one and two units), and they all work very well. Until 2022, I did not encounter the need to add parallel blocks to an already existing system.

Last year, I needed to add a second inverter to one already running in a single-phase system. Both inverters were of the same modification: MultiPlus-II 48/5000, had the same "product ID" 2623 and the same "PN" PMP482505010. The only difference between the inverters was that one of them was bought two years earlier than the other.

Of course, I carefully studied these official documents from Victron:

Parallel, split- and three-phase VE.Bus systems

VE.Bus firmware versions explained

Theory on wiring systems

Wiring Unlimited

The official documentation says: "All units in one system must be the same type and firmware version, this includes the same size, system voltage, and feature set. The type is indicated by the first four digits of the firmware version number."

It also says "For units in parallel: Both the DC and AC wiring needs to be symmetrical per phase: use the same length, type and cross-section to every unit in the phase. To make this easy, use a bus-bar or power-post before and after the inverter/chargers. Also, apply the same torque on all connections." ... and so on.

But as practice has shown, all this is not enough, and if "same type" blocks have different hardware revisions, then they may not work smoothly when connected in parallel. But this is not mentioned in the documentation.

Before adding the second inverter, I updated the firmware of both inverters to the latest version 496 at that time, and then configured them for parallel operation with identical settings. The AC and DC cables between the busbars and each inverter had exactly the same length, type and cross section (6 mm² for AC and 70 mm² for DC). The fuses were exactly the same for each block, and all terminals were tightened with the same torque. And despite all this, the old inverter was loaded more than the new one.

At full load the difference is about 10%, at light load it is about 300%. This resulted in the cooling fan running on only one inverter at medium loads, and when approaching maximum load, the "Overload" LED also flashes on only one inverter. As a result, it is impossible to get the maximum power of both inverters, since one of them will be overloaded earlier and turn off the entire system. I am attaching a screenshot with several current measurements at various loads. All measurements were taken with the external grid switched off, the MPPT chargers and the Fronius inverter were also switched off. I just turned on and off various loads and recorded the readings. The system was controlled by an Octo GX running the then latest version of Venus OS 2.87.


After fixing the results, I did some experiments, changing the length of the cables on the AC side to balance the load of the inverters, but it did not help. Even when I increased the length of the cables on one inverter several times over the other, it had very little effect on the load ratio between the inverters. For example, if at the same cable length at a certain load the ratio was 1.8, then when the cable length was doubled for a more loaded inverter and the same load, the ratio "improved" only up to 1.6. Even a tenfold increase in length for a more loaded inverter did not allow me to compensate for this imbalance. I changed the blocks in places, it did not help either. I carried out a similar experiment on the DC side, without getting the desired result. I even did additional tests without fuses on the AC and DC side to rule out their influence.

Having removed the front covers of the inverters, I found that their internal structure has many differences, that is, they are definitely different hardware revisions. At the same time, the hardware revision (05) was indicated on the old inverter, but it was not indicated on the new one (I am attaching a photo).


After researching similar situations in the Victron community, I found that other installers are also facing a similar problem.

Here is one of the most detailed situations where the user @MarekP was able to solve the problem only after replacing one of the blocks with a block with identical hardware revisions:

How to balance 2 MP-IIs in parallel

I ended up not being able to solve the problem at the time, and the customer was somewhat dissatisfied as he couldn't get full power from the two inverters.

But now I have a similar situation. A few months ago we installed one EasySolar-II 3000 (SN: HQ2230TPXDW, PN: PMP482307010) for our client. Now this customer has asked for a MultiPlus-II 3000 to be added in parallel to double the power. Two options are currently available in E-order: PMP482305010 and PMP482305012 (as far as I know, they are identical, but are produced in two different factories due to high demand). I'm afraid to face the same problem if the revisions of the already working EasySolar-II 3000 and the new MultiPlus-II 3000 are different. At the same time, I can't find information anywhere on how to check the revision number by the serial number of an existing inverter, and how to find out the revision number of new inverters available in E-order before buying. Does anyone know this?

If they have different revisions, then it's better for us not to risk it and buy a more powerful EasySolar-II 5000 instead of the already working EasySolar-II 3000. Of course, then we will have a new problem - to sell someone the already used EasySolar-II 3000 with a loss of value, but at least our client will be happy with the result.

To summarize, I have two questions:

1. What should I do with the first system I couldn't balance last year? The client resigned himself to this state of affairs, but it cannot be said that he was satisfied. I would like to somehow correct this situation.

2. What should be done in the future in such situations, when it is necessary to add an additional inverter to an already operating system? How to check block revisions in advance?

Thank you!

romarub asked
marekp edited ·

6 Answers

Multiplus II 8000 parallel


what is the reason for the Multiplus II 8000 and 10000 not to be able to work in parallel mode. Will this be fixed by a firmware update in future or is it hardware based, thus all Multiplus II units installed now will never work in parallel mode?

Thanks for your feedback.


nam-erik asked
Matthias Lange - DE answered ·

1 Answer

Multiplus in parallel leads to unbalanced currents

The setup is 3x Multiplus II 48/5000/70-50 in parallel mode single phase.
One Multiplus is from 2020. The other two are new from 2022.
AC cable lengths are equal and not oversized.
DC cable impedances are equal as possible between the units.

Unfortunately, the Muptiplus from 2020 draws a much higher current from the battery than the two new ones. The two new Multiplus currents are almost equal.

Test Inverting Test Charging
Nr. Serial number AC length [m] AC [mm²] DC [mm²] Firmware AC Limit [A] DC [A] DC [A]
1 HQ2219MY2DF 6 6 70 497 10 37 16
2 HQ2218AXMNP 6 6 70 497 10 38 18
3 HQ2037MH5DX 6 6 70 497 10 47 39

It seems that the "problem" is the old Multiplus from 2020. I think there were design changes on the PCB. PCB dimensions have changed. And the new ones show an unpopulated terminal block. (see pictures)

I bought the old and new MP at different shops.
I am not sure who can give support.

Can someone from Victron check (Serial numbers) if the Multiplus can work together?




pripp asked
pripp edited ·

4 Answers


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