Unanswered Questions in Multiplus-II

Referring to the Documentation Note "AC-coupling and the Factor 1.0 rule" the Multiplus II is shown connected with PV Inverters to allow a grid-tie configuration. Can this configuration work with the Enphase IQ7+ modules (PV Inverter)?

Will this allow these two conditions to exist on a 60 Hz system?

1. Multiplus-II will use solar power (through the Enphase IQ7+) to charge 48 Vdc battery bank when grid is not present.
2. Multiplus-II will allow Enphase IQ7+ modules to back feed to the power grid when the grid is present.

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Hi Everyone,

I have a Multiplus 2 48/5000 with Pylontech batteries and a Cerbo GX.

The DC Bus voltage that the Multiplus is displaying seems to be about 2 Volts too high even when there is no charging taking place.

I understand Ohm’s Law and how this affects voltage readings.

I’ve verified the voltage readings both at the DC terminals of the Multi and at the batteries with two different DMM’s and this indicates that the Multi is reading the DC Voltage inaccurately.

I’ve checked all connections are clean and firmly secured.

The inaccuracy seems to continue to increase over time.

I’ve heard that returning the Multi to the dealer for recalibration is one option (not sure if it’s correct) and I wanted to ask the community if adding a smart shunt would be a better long term fix?

Regards,

Shanon.

Hello there, I've already posted in French community but posting also here to have wider reach.
I have an installation with a Multiplus II 48/10000/140 with 5 Pylontech US3000C batteries, and just under 3kWp of PV field. The whole "house" is powered by the Multi.

Installed at the end of December 2022, everything worked perfectly, even beyond my expectations it was really top. I say it was because this night at 5 o'clock power cut, nothing powered anymore in the house. The multi was off with only the "low battery" light and the Pylontech in "fault". At first I thought it was a power cut with the batteries empty, but the power from grid was ok. When I removed the lower cover that protects the connections, I saw a piece of broken component marked on it "072N10N" it's a power transistor so it sucks. Looking underneath in the power block on the right, I can see the exploded transistor.

To specify the context, at the time of the cut, the Multi was in scheduled charge (limit to 80A to the batteries) because I'm in off-peak hours during the weekend thus not need to solicit the batteries, and the batteries had been charged from midnight to 1am approximately to reach the threshold of 65% that I fixed. So when the threshold was reached, the Multi was not using the batteries and he had to pass only 800W from the grid to the house. So it's not possible that it's due to a load peak.

I turned off everything, disconnected the Pylontech from the Multi, connected the Cerbo on a 12v transformer to get some visibility. Then I turned back on the Pylontechs which are ok again and seen by the Cerbo with a 64% SOC, fortunately they are ok, I hope.
On the Multi, errors: Grid lost, low battery and high discharge current and when I tried to turn it back on I quickly shut it down because the smell was not great. I tried to turn it on in "charge only" mode ditto, just the "main on" light on.
I think I'm good to use the warranty, too bad.

Has this ever happened to anyone? I thought Victron products were very reliable, so I must be out of luck.

Thanks in advance for your advice and feedback.

Bonjour, j'ai une installation avec un Multiplus II 48/10000/140 avec 5 batteries Pylontech US3000C, et un champ PV d'un peu moins de 3kWc. Toute la "maison" est alimentée via le Multi.

Installé fin décembre 2022, tout fonctionnait à merveille, même au delà de mes espérances c'était vraiment top. Je dis c'était car cette nuite à 5h coupure de courant, plus rien. Le multi était off avec uniquement le voyant "low battery" et les Pylontech en "fault". J'ai d'abord cru à une coupure EDF avec les batteries vides, mais l'arrivée EDF était bien ok. En enlevant le capot inférieur qui protège les connexions, j'ai vu un bout de composant éclaté indiqué dessus "072N10N" c'est un transistor de puissance donc ça craint. En regardant par en dessous dans le bloc de puissance à droite, je vois bien le transistor explosé.

Pour préciser le contexte, au moment de la coupure, le Multi était en charge programmée (limite à 80A de charge) car en heures creuses le week-end donc pas besoin de solliciter les batteries, et les batteries avaient été chargées de minuit à 1h00 environ pour atteindre le seuil de 65% que j'ai fixé. Donc seuil atteind il n'utilisait pas les batteries et il devait passer seulement 800W depuis EDF vers la maison. Donc pas possible que ça soit dû à un pic de charge.
J'ai éteint tout, débranché les Pylontech du Multi, connecté le Cerbo sur un transfo 12v pour retrouver de la visibilité. Puis rallumé les Pylontech qui sont de nouveau ok et vues par le Cerbo avec un SOC à 64%, heureusement qu'elles n'ont rien, enfin j'espère.
Sur le Multi, erreurs: Grid lost, low battery et high discharge curent et quand j'ai essayé de le rallumer j'ai vite coupé car une odeur pas top. J'ai essayé d'allumer en mode "charger only" idem, juste le voyant "main on" allumé.
Je pense que je suis bon pour faire jouer la garantie, mais vraiment galère.

Est ce que c'est déjà arrivé à quelqu'un ? Je pensais les produits Victron hyper fiables, donc je ne dois vraiment pas avoir de bol.

Merci par avance pour vos conseils et retours d'expérience.

I'm shopping for a MultiPlus II but it's pretty difficult to determine what the differences are between models. I want the 2X120V version and i know that its model number is PMP122305100, but I found what seems to be the same version at a lower price from another seller, but the model number is PMP122305110. Does anyone know what the difference is ? Thank you !

So I use Mode 2 to set the grid set point. Using it for several months. From time to time, the MultiPlus-II completely ignores the grid set point and acts erratically. It switches between Bulk (charging) and Discharging every few seconds, and sometimes shows "PassThru" in the GX interface.

Normally this rarely happens (once every few months). Or at least, I rarely notice it happens. But recently, I noticed this behavior twice on a single day.

In the morning, the custom control had the grid set point set at 2690W. I noticed that the grid set point was not reached at all. Even though the battery was not full or there was any other obvious cause for this behavior.

The MultiPlus-II was drawing 1000-1200W from the grid at that point. Far from the 2690W requested. I switched to Mode 1 by disabling the custom control. The MultiPlus-II did not "recover" even though the grid set point was now fixed at 2690W for quite a few minutes. I finally ended up taking some screenshots before resetting the MultiPlus-II through the GX menu. After all was back up, the MultiPlus-II behaved nicely again and I re-enabled the custom control.

A few hours later, I noticed the MultiPlus-II was behaving erratically again, seemingly doing its own thing, completely ignoring the grid set point. I again disabled the custom control and set the grid set point to 0W manually (in the GX device). To no avail.

In stead of resetting the MultiPlus-II, I decided to try something different this time. I shut down an electric fan heater (consuming approx. 500W) and low and behold, the MultiPlus-II started honoring the grid set point!

I am collecting some key metrics of the MultiPlus-II like input and output voltage, current, frequency, power. When storing these metrics however, they get averaged out over 10 seconds. So the quick charging/discharging behavior is lost in the process.

I am using a MultiPlus-II 48/5000/70-50, firmware version 494. Any idea if there is a known firmware bug on this?

If not, would it help the firmware development team having "debug" data every second?

I'd like to better understand how charging is managed and hopefully find a way to improve charging speed if possible. I have a four hour cheap rate window in which to maximally charge my battery stack. It is problematic to get the system close to fully charged from its minimum SoC. System is 2x parallel MPII 48/5000/70 with 6x Pylontech US5000.

If I understand correctly, the charging process or, at least the overall parameters for it, are mostly managed by the Pylontech BMS. From the victron doc it clearly states the dynamic charge voltage and charge current limit (CCL) are controlled by the Pylon. I don't however understand *what manages the overall charge current supplied* at any given time. The CCL certainly changes, but only when charging gets close to full SoC ~90%, or if the battery is particularly cold. The system charge level rarely gets close to the CCL.

Looking at the graphs, during the ESS scheduled charge window, charging seems typically to have three phases - an initial relatively high level until ~1.5hrs in and around 50% SoC, then a medium charging phase that bounces around, and finally a very slow charging rate as we approach full past 90% SoC.

What part of the system controls the charge current level?

Why does it drop from the higher current charging to the lower after ~1.5hrs / ~50%?

Is there any way I can influence this control algorithm?

Perhaps the Pylontechs or Multiplus' are doing thermal management to an extent - though it doesn't seem that warm? Pylontech charge derating is supposedly only active outside of ~12C and 43C.

Appreciate any insight into the charge algorithm, and/or comparisons with other peoples systems.

Cheers, Paul.

A good night - starts at 16% SoC and gets to 98%:

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Not so good, start 11%, finish 88%:

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Start 11% end 92%:

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Start 11%, end 92%:

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Final example, start 34%, end 98.8% (highest ever seen):

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Hello everybody!

I read through multiple articles and also Victron's documentation about cable length, but I am still not 100% sure, so I decided you bother you here with my questions :-)

I use a setup with 3x Multiplus II, 3x Skylla-i Chargers, 2x MPPT, 4x SmartLithium. Everything by Victron.

Everything (except the batteries) is connected to a generic bus bar and then connected to a Lynx BMS + Lynx Distributor. The batteries are connected to "the other" side of the Lynx distributor - all in parallel.

CerboGX:

I am using a CerboGX for managing everything. Everything is connected together. In the "System Setup" I use as "battery monitor" the "Lynx BMS". In "DVCC" I set "SVS - Shared voltage sense" to "Forced on". My idea behind that the voltage at the BMS is the "real" voltage that all the devices (Multiplus, MPPT, Skylla-i) should adjust to.

Batteries:

All batteries have the same cable length (plus and minus). Each of them are connected to the Lynx Distributor. I think this is okay, since the cable length is as it should be.

Multiplus:

I currently use a parallel single phase system, but will change it to a three phase system soon. However, they are running as one "cluster". Currently I have the same cable length, but it is pretty messy. I only have about 0.5 meters of length. The cables have 50 mm².

Question #1: Is it possible to have different plus and minus cable lengths between the Multiplus? Example: MP 1: 0.3m, MP 2: 0.5m, MP 3: 0.7m

Question #2: Is it possible to have different length of plus and minus cable? For example: plus cable: 0.5m and minus 0.7m?

Skylla-i:

The Skylla-i chargers are connected to a small busbar and then connected via a 2.5m cable to the "central" busbar. The three Skylla-i also run in a parallel cluster.

More or less I have the same questions as for the Multiplus, but the main question is: I have a way longer cable to the central busbar, than the Multiplus. More or less the Multiplus and the Skylla show the same battery voltage.

General question:

I currently also have the issue, that the Skylla-i is not charging, when the Multiplus is charging. Right now the Multiplus is Inverting and the Skylla is in Storage mode. I would like them to work in parallel mode. Is this because they see a slightly different voltage?

Sorry for that long explaination and thank you in advance for your ideas/experiences!

Best regards

Alex

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.

Thanks.

Jason

I have a raspberry pi that communicates with the Cerbo GX and the Multiplus 2 through the modbus registers in codesys. However, when trying to write the register 62 to perform a system reset when the relay test is not completed and in pending mode, when trying to write this register the whole multiplus modbus tcp communication will not be stable anymore. Like literally it could break the modbus connection with the moltiplus randomly. Is there any explanation for this? Thanks in advanced!

Is it possible to just use a relay to cut off ac consumer circuits exiting from the Multiplus inverter. As in a low voltage/soc situation. Seems cheaper than a giant contactor to cut dc supply to inverter. Am I missing something? Just looking at simple bms at the moment with no can bus comms. Or can I use simple relay to change mode remotely?

The Multiplus-II 48/5000/70-50 smells on one of the phases (3 phase installation) during operation.

I have an installation:

3x Multiplus-II 48/5000/70-50 (3 phase)
2x MPPT 250/100
Cerbo GX - Ve.CAN, Ve.Bus connected
Lynx Smart BMS
2x Lynx Distributor
4x Smart Battery 200Ah/24V (400Ah 48V system)
1x Fronius Symo 6.0-3

The installation worked perfectly for 4 months, but today for the first time there was a smell like burnt laminate/plastic from the Multiplus on the L1 phase. It smells more on the left side of the Multiplus at the bottom. Now in the evening I opened the housing of the Multiplus, nothing smells at all anymore. I looked carefully, there are no burnt cables or components, everything looks like new, everything is clean, the fan is spinning.

I checked all the cables again, they are tightened with the correct torques, there are no suspicious things anywhere.

- Wires:
AC 5x10mm2
DC 2x70mm2

- ESS set with PV inverter on AC-OUT
- Fronius works properly set as Microgrid MG50 - checked, frequency control works.
- Charging current set to DVCC max 200A (wasn't exceeded because I watched almost all day)
- Room temperature around 15°C
- There are no error messages
- Everything works fine, it just smells.

What has changed in use for 2 days is:

- export of energy to the grid was performed for the first time

- almost the first time the battery was charged by Multiplus from 230V (before that I only charged it twice from the mains to balance it and it was charged from MPPT)

- Fronius Symo 6.0-3 has been connected to AC-OUT1

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What to do next?

What to check?

Thank you in advance for your help

Looking at unorthodox charge set up to allow excess PV production to be used. System so far; Multiplus-ii 48/5000 - AC in connection to house dis board, AC 2 out connected to dump loads, switchable between various loads. CT clamp on main incomer - to multiplus. 18no. Eve280lk in series. JK BMS( works great with multiplus / VRM ). Victron MPPT 150/35 with 4xPerlight 415w panels 2P2S - DC-DC. SMA3600 AC-AC grid tied with FIT tariff. Before the Victron/ battery installation, was using a PV router ( senses export with CTclamp on incomer to divert excess electricity to 2 seperate loads - suitable for priority), this worked brilliantly for years. Dream set up would be. MPPT to charge say to 64v(can't figure how to with below) multiplus to charge to 58v(can't figure how to with the above) AC2 out on at 57.95V( no problems) PV router would then divert excess from AC - AC SMA, with MPPT to carry on charging batteries. 150/35 still to be visable / logged on VRM(possible?). Also Aux relay to control dump in addition on AC 2 out(easy with assistant's). Currently can't get multiplus-ii to play ball, as soon as I disable DVCC the multiplus goes into a tizzy / report low battery and stops all charging/ goes into pass through. Best set up I can come up with is. Multiplus-ii with DVCC on / BMS connected to control multiplus charge &MPPT voltage charge points. Dump loads on AC 2 out ( AC2 with assistant to come on at XXv), PV router also on AC2 out with additional relay controlled from AUX relay on multiplus-ii to come on at XXv. Any help / pointers appreciated.

Hi

I hope som of you can help me with my problem.

My setup

- It is 24v
- 4 x MPPT 100/50
- 1 x Multiplus ii 24/3000 (connected ESS connected to earth)
- JKBMS 8S 280AH

My problem

I have som strange voltage fluctuations on specific cells according to my BMS (A meter shows stable voltage)

1.jpeg
As you can see cell 7 is all over the place (blue line) and this is with 300-400W load on the multiplus inverter + the mppts are charging.
(you can see the load amps in the graph)
I tried replacing the balance leads with no effect.

Then I tried turning off the multiplus and only charge with the mppts.
3.jpeg
And then the fluctuations despaired?

Info about my JKBMS

2.jpeg

Do any of you have an idea of what is happening?
Can the inverter make some kind of noise running back to the BMS ?
Can I connect the BMS/battery too close to the inverter ?

Good morning everyone,

I have a simple system installed on my Camper.

The Multiplus 3000/12/120, combined with an SmartSolar 100/50 and an Orion 12/12/30, interfaced on a Cerbo GX together with a Smartshunt 12/500A. The battery is a 200Ah LiFePo4 with integrated BMS. The temperature and voltage sensor of the Multiplus and Smartshut are installed correctly.

The MPPT manages to bring me the recharge up to 100%, then maintain and compensate with the loads present at the moment.

The Multiplus unfortunately not.

Fast charge up to 85% after changing to float.

I can't figure out where I made the wrong settings and why if all the devices read the SOC from CerboGX it's like making an exception.

Thank you all.

HI

David