marekp avatar image

My BMS tells MultiPlus-II not to charge or discharge but MultiPlus-II ignors it.

MP-II has the proper assistant loaded.

BMS indicates that is telling MP-II not to charge o discharge, but I see current going back and forth on the battery.


Is keeping the battery at "Float" voltage not considered charging or discharging?


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I think it would be best if you could supply a wiring diaram of how you have connected the BMS and also a list of the assistants you have installed, and screen shots of the setting.

If its wired and setup correctly then it will work

@Paul B

I have only one assistant loaded (two signal BMS assistant).

My BMS is properly connected to Aux1 and Aux2 with the proper signals (dry contacts).

When temp is below 5C BMS opens the contacts on the charge and discharge channel.

Most of the time, when temp is below 5C, MultiPlus-II would not invert, but not always.

From VRM graphs you can see that when grid fails for a moment, MP-II is turning OFF, but not in all instances.

My question is why not always?




The screen shot of assistant setup you can find here (system will not allow me to post them here):

I would download the DATA its next to the widgets looks like a cloud symbol and select excel and go over the data and work it out from there. Also Manually trigger the events and follow it through and see what you get. also check to make sure you have the latest firmware and assistants, I cant help you much more than what I have suggested, you will now have to look at the data and work it through

@Paul B

I downloaded data from the cloud many times.

It does not show anything different than the VRM graphs.

System is charging and discharging my battery when temperature is well below 5C.

It does that not always, but this is even more concerning.

Charging and discharging current are not high but only because my battery is now fully charged. System is no yet connected to my house circuits.

At this point I have no confidence in its ability to work properly.

As per your suggestion I performed an experiment.

1. Today From 12.04 to 12.04 I switched off the grid with BMS set to prevent charging/discharging below 5C (current temp is 2C)

2. Today From 12.07 to 12.08 I switched off the grid with BMS set to prevent charging/discharging below 1C (current temp is 2C).

What happened.

Ad.1 The system switched OFF

Ad.2 The system switched to INVERTING mode

As you can see, the signal from my BMS changes with the different temp limit setting and MP-II reacts to it.

I downloaded data for this period from VRM cloud and it look very funny.

Ad.1 The system did not register grid OFF (Grid OK in the last column of cloud data)

In the second half of the fifth minute it was charging the battery (1.7-1.8A).

There are columns with the OFF value that have something to do with charging, discharging, BMS and user settings.

#3 Charge disabled by BMS
#4 Discharge disabled by BMS
#5 Slow charge is active
#6 Charge disabled by user setting
#7 Discharge disabled by user setting

AC INPUT column shows INVERTING when in reality the system was OFF ???


VE.BUS STATE column says OFF

VE.BUS ERROR column in only one row says "VE.Bus Error 1: Device is switched off because one of the other phases in the system has switched off"

The most puzzling column is SWITCH POSITION.

I would think that it is just a record of the position of this (I-0-II) switch.

I have it on (I) position and never on (II), but this column is showing it flipping back and forth between (ON) and (CHARGER ONLY)

I understand that (ON) is position (I) and (CHARGER ONLY) is position (II)

Ad.2 Here data looks a bit more logical

To bad I am not allowed to attach cloud XLS file.

I am not sure if you can trust those columns in the data extract. I had a situation a few months back when my voltage rose to about 31v and 20A being pumped into the bank. I had no alarm on the Cerbo GX, the Victron Smart Batteries (via bluetooth) reported a change disconnect, my Wakespeed 500 Alternator reported a forced switch to float. Looking back at the data today those columns are all off.

I have posted asking for details on what alerts are raised, and what is available in VRM and not had any response. These values might be for the Can.BMS attached batteries rather than VE.Bus or 2-Wire Assistants signalled through the MultiPlus.

It might be that you need to manually check the signal wires to understand if it is the MultiPlus or BMS that is playing up and not reacting properly.


Thank you for your time spent on answering to my problem.

What you saying is not very reassuring.

I also suspect that those BMS columns in cloud data are for Victron's BMS, but what those USER SETTINGS are for?

I checked the signals from BMS 100 times and even simulated them with jumpers.

In all instances MP-II behaves illogically, and data from the VRM cloud is adding to my frustration.

Some time ago Guy told me here on this community that I should not expect help from Victron since my BMS is not supported.

I am starting to regret getting involved in this hardware.

I have a VE.Bus BMS, which I have used on the VE.Bus with relevant assistant and off the VE.Bus with the 2-Wire Assistant. I have never seen those values in the VRM data log at anything other than off. I have had a few simulated Load and Charge disconnects and next time I do one, I will look at those data elements, but do not expect them too change. I have also never seen the VenusOS or VRM report when I have had a charge or load disconnect, which I think is wrong.

It is probably safe too say that if the MultiPlus is not reacting to the signal being received by the 2-Wire BMS then Victron will listen as it is a bug, but I very much doubt there are any. However if the issue is related to the BMS and how it is driving those signals then I agreee, you are likely on your own. What BMS are you using and does that BMS manufacturer have a forum somewhere that can help on that side of things.


As I indicated here I have 123smartBMS. It was not cheap at 500 Euro.

I consulted my problem with its manufacturer and he does not see any problem in my BMS unit. He was surprised that Victron said that his BMS is not supported and refused to help me as long as this BMS is used.

He even has a YouTube video showing his BMS connected to Victron units.

As I said, my MP-II reacts the same even if I simulate BMS signals with jumpers.

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From my understanding there are 3 control triggers (I have NEVER setup/worried about the temp one as I am never going to see -5Deg C) and maybe a simpler way is to use a VE BMS unit, as this device has 3 normally closed circuits 1 for low 1 for H and one for Temp. these are used with the victron batteries and ITS not recomended by victron to use them with anything else. (but this may work for you domt know) but this to me indicates there are 3 controls not just 2 that you have setup (maybe wrong here as this is just my thoughts) just trying to be helpfull in some way OK.

I dont know what your batteries do when its two cold so it maybe there that you should look.

1 . high voltage trigger Turns off Charge ONLY

2. Low Voltage trigger Turns off Loads (Ie inverter ONLY)

3. Cell temp high or low Turns off BOTH Charge and Load

have you got all 3 setup, and is there a temp control output from the batteries if yes then setup a assistant to control it as the 3rd input

I am not experienced in this Low temp area and thus OTHERS may have better input and sugestions

@Paul B

Thank you for your input.

I have 16 Winston LiFeYPO4 200Ah cells connected into 48V pack.

I am using 123smartBMS with temperature sensors for each cell and 2 relays for Inverter/Charger control.

It uses logic described in this table:


I see no problem in this BMS behavior.

It sends the correct signals to AUX1 and AUX2 inputs of the MP-II. (checked with multi-meter)

I have a problem with how the MP-II reacts to this signals. (proper assistant is loaded)

The data I downloaded from VRM cloud would be funny if it was not scary.

I tried to get help from Victron distributor of those units, but he never returned my calls and now he is not even picking up his phone.

I called the other Victron distributor in my country and this one was no help at all because I did no buy those units from him.

So, I am left with this community to find the answer to my problem and I have hard time finding it.

@MarekP, I sense and understand your frustration.

Can you clarify.

Do you have a relay or onto coupler between the BMS and the Aux ports, such that the aux ports are either closed or open by the relay / onto-coupler ? A diagram might be useful.

If you break the connection between the pins on the Aux port used for Charge Disconnect (causing it to open), dose it stop charging? If you do the same on the Aux port for Load Disconnect does it stop inverting? If this is happening every time, then the MultiPlus is working. It is dumb and just reacting to the dry contacts being opened and closed. Have assumed the system is set for open as disabled and closed is enabled, if those are reversed then reverse within the text as needed.

If the MultiPlus is working as expected and reacting to the open/closed status of the Aux ports then is the BMS correctly triggering a charge disconnect / load disconnect.

What is reporting the temperature, is it the BMS itself or a separate measurement. Could there be a difference between the BMS measurement and your other measurement. I know on the Victron Smart Lithium batteries that the temperature reported through the Bluetooth app is generally higher than the temperature I measure with a probe attached to the outside of the battery or battery terminal.


Thank you again,

Below is a link to maker of this BMS. There is a FAQ section and there is a specific answer regarding connecting to the Victron MultiPlus.

There is also a link to the YT move with this setup.

This BMS uses relay with dry contacts.

As I mentioned already, I tried to replace signals from this BMS with jumpers, and MP-II behaves the same.

The experiment I conducted proves that MP-II registers the AUX inputs and acts on them but not all the time.

It does not do that when is in a FLOAT charge.

This BMS has the temp sensor on each cell and only one cell below T-Min will trigger the "not to charge" and "not to discharge" state of those relays (they go open).

There is maybe 1 deg difference between MP-II temp sensor and BMS sensors, but you can see on the graph that temperature is well bellow 5C. More like 1 or 2 degrees.


If you believe you have it all configured and wired correctly, then you need to clearly document all your steps, including clear output and system behaviour at each step and send this to the dealer you purchased the MP from and ask for help as their is iether a bug or hardware issue.

I very much doubt you will get any further support from the community here.


See my answer to your other post.

2 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @MarekP

Without diving deep into the issue (yet), some remarks / observations:

-why are you disabling discharge at low temperature? most batteries are allowed to be discharged at much lower temperatures then being charged.

-a less than 1A charge is not considered 'charging' and also no problem for the batteries. (the way ESS works it's not always possible to keep at 0A)

-with any BMS it can take a couple of seconds before the system reacts, I don't know how long it takes in your system?

-how did you configure the BMS assistant? 'force to float' or 'disable charger' when allow to charge is disabled?

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@Daniël Boekel (Victron Energy Staff)


1. My BMS does not have the separate T-min for charge and discharge. That is why when I set it to 5C, discharge and charge are disabled when temperature is below T-min. There is the table for this BMS in one of the post in here.

Also this is why in another question I was asking why MP-II cannot be set up to stop charging Lithium batteries when temperature goes below 5C. If it could, I would set T-min in my BMS to, let say -15C, and I would have different minimum temperature set points for charging and discharging. One in BMS and the other in MP-II.

2. I am new to this lithium_dying_when_charged_below_0C so I would prefer not to take risk on any charging when it is dangerous for the health of the battery. My cells supplier told me that I will loose my warranty if I charge them at below 5C. One of the local Victron distributors said that "if someone tells me that lithium battery cannot be charged below 5C, he is stupid because all batteries cannot be operated outside the 10C-20C temperature range".

In this situation the charging current is higher than just 1A. I can see 1.7-1.8A on some of the graphs i posted here and in the VRM cloud data I downloaded.

BTW this VRM cloud data is very strange and illogical in many places. You can find my take on them in one of the posts here.

I am not using ESS yet and probably will newer do, because I do not know what grid code to chose, and my Victron distributor is of no help at all. My contacts with Victron distributors are a disaster.

I do not want to repeat myself here so you can find this in my discussions with Paul B and bathnm.

3. The reaction time is up to MP-II since this BMS just makes or breaks the contacts on MP-II's Aux inputs. When temperature is below T-min the signals from BMS on the Aux inputs of the MP-II are permanently open.

4. As for my setup of the "two-signal BMS" assistant it is set in default, apart from Aux-1 and Aux-2 instead Aux-1 and "Temp sensor".

I was a bit disillusioned about this "To-signal BMS" assistant when Guy told me that to fix my problem I have to remove this "Two-signal BMS" assistant or use supported BMS. He implied that my BMS is unsupported, but I never got from him the list of supported ones. (I mean BMS and not batteries with BMS).

You can find screenshots of my VEconfigure pages in here:

I am actually surprised that even the Winston cells are not allowed to be charged below 5C when manufacturer of this cell states that they can be charged down to -25C.

Hi @MarekP

I hope you'll understand that I cannot read every comment plus reactions to it, so I go back to the basics.

your settings look fine, and yes, without grid connected the system should switch off if no BMS is connected or charge / discharge enable is open.

Winston cells: when these are indeed the LiFeYPO4 version (Y = Yttrium) then yes they can be charged safely to much lower temperatures.

Also, 2A into a battery of 200Ah plus, is really no problem, some battery manufacturers even have in the datasheet what the maximum charge / discharge current is at different temperatures.
A BMS that doesn't have different temperature limits for charging and discharging is not a BMS that I would use.

On 'supported BMS' that is a thing that we just cannot offer, as all these BMS systems can be setup in a lot of different ways, it's just not possible to support them officially.

But: don't worry, most such systems work just fine, and as you see, we (and other users) do help you with it on this forum.

One other brand I have good experience with is REC, they have a BMS that talks CANbus with the Victron GX device.

marekp avatar image marekp Daniël Boekel (Victron Energy Staff) ♦♦ ·

@Daniël Boekel (Victron Energy Staff)


Thank you for your answer,

Of course I understand and I hope you did not take, my pointing out that something is written by me somewhere else, as complaint that you did not read it.

The cells are marked as:


And Winston sent me this charging spec for them:


The problem I have is that the supplier of this cell says that they cannot be charged below 5C and if I do warranty is "null and void".

I agree that my BMS, at the moment, is not perfect, but I was informed by its maker that they already have new firmware and app that will include separate T-min setting for charging and discharging.

On supported or unsupported BMS, there was a problem not with BMS but with Two-signal BMS assistant setting. The problem was solved but it was a "bumpy ride". :)

This REC BMS is even more expensive than 123smartBMS.

You know, it took me 6 years to save enough money to finally be able to build this system.

What you think of the situation, when Victron distributor tells the client that he can pick any grid code from the list because it does not matter what is selected?

Related question, are Victron MultiPlus-II and EasySolar-II GX certified for use in Poland?

I know that I should ask this question before purchase but it is "better late than never".



Hi @MarekP

I don't know all the different grid codes, you could check if grid code 'Europe' is compliant?

I cannot help you with your battery supplier, sorry :)

marekp avatar image marekp Daniël Boekel (Victron Energy Staff) ♦♦ ·

@Daniël Boekel (Victron Energy Staff)


I was under impression that the grid code is one of the important setting as it is controlled by a password.

When someone, from Victron, tells me it is not important what I choose makes me confused.

Do you know who can tell me what grid code to select for Poland?

I wanted to use ESS assistant, and it requires the grid code selected.

As for may battery supplier, the warranty is only one year and I am 6 month into it.

As long as I know that it is save to charge at low temps there is no problem.



Hi @MarekP

if there is no grid-code available, use Germany as that is a very safe one.

Please note that to comply with local regulations you'll have to install an external LOM detection device.

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and: default assistant settings will 'force to float' and try to maintain float voltage, so it can actually charge if DC voltage is below float voltage. select 'deactivate charger' instead of 'force to float' to change this behavior.

marekp avatar image marekp Daniël Boekel (Victron Energy Staff) ♦♦ ·

Thank you for this info.

I will try that.

Paul B avatar image
Paul B answered ·

Hi Marekp, Now lets step back a bit here

You have purchased gear ONLY from a Victron Dealer you did not pay them or get them to install it and when you have problems you want them to spend there time without payment to help you fix your install that you did not pay them to do with products that are not all Victron products.

I sugest that you consider paying them for there time and then I am sure they will resolve the issues for you.

SO AS you dont even have all victron gear, and I don't know were you purchased it all from

(and as a EXTRA NOTE I do NOT work for VICTRON in any way shape or form so please don't blame them for these comments I have just left).

The victron BMS Assistant works fine and I have used it heaps of times and have had no issues with it.

However if you do find a issue then I suggest that you list the steps in a step by step process EXPLAINING in detail HOW TO DUPLICATE THAT ISSUE/PROBLEM) the issue that you are having (IT MUST BE DUPLICATEABLE) in a step by step 1,2,3,4,5 etc and here is the issue/problem. then someone here in the form maybe able to help you further.

you can do this quite simply by, as you say closing or opening (which ever way you have set it) aux1 and or aux2 one will stop the load and one will stop the charge. and if both are triggered then both I presume would be turned off. now if this is NOT the case please show how its done.

if this is not the case then explain were and how and send detail schematics of your victron setup and screen shots of the assistant setup as well and all settings.

inc model numbers and firmware version of the victron gear that you are using.

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@Paul B

Why I am not surprised that someone would eventually bring that argument, but I am surprised that you did not read my post with attention.

Let me repeat:

"I tried to get help from Victron distributor of those units, but he never returned my calls and now he is not even picking up his phone.

I called the other Victron distributor in my country and this one was no help at all because I did no buy those units from him.

So, I am left with this community to find the answer to my problem and I have hard time finding it."

But you say it is OK for Victron distributor, from which I got my Victron units, to ignore my messages left with his employees, and not picking up his phone now?

It is OK for the other Victron distributor to ask 700 Euro for just to come and try to program my setup (He is 60km from my location) and refuse to answer questions over the phone.

Oh no sorry, he answered one question.

When I asked him what GRID CODE (ESS needs it) I should program into my system because I cannot find my country on the list, he said "it does not mater, pick one from the list". (So now I do not even know if my Victron can be legally connected to the local grid!)

Tell me why there is a password on that setting if it does not matter what I select?

As for BMS assistant. It works in your systems, but did you install all Victron systems there are?

What if my unit is faulty? (It already had a problem with the freezing of the GX display)

Maybe FLOAT charging is not considered by Victron engineers as charging?

Why Victron even wrote this "Two-signal BMS Assistant", for other then Victron batteries, when there is no support from Victron when you try to use it, and you purchased the battery and BMS for it with the understanding that it will work with MP-II made by Victron?

As for test you suggesting.

Are you saying that the test I performed is not answering your questions?

Look closely, System is charging and discharging my battery when BMS is telling it not to.

What else you want to see?

You suggested to download the data from the VRM cloud, and I did.

They look so funny that it is scary.

Screen shots of my Victron setup are in the other post that I posted link to.

Did you see it?

Do not take my questions personally, and please understand me, who spent over 10000 Euro on the system and cannot use it.

You do not want to know how long it took me to save this money.