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erichabg avatar image
erichabg asked

How to control charge current of Multiplus with node-red on Cerbo GX

For some years I have controled my Multiplus (old Version not II) with a raspberry pi via two DAC and the assistants for "Charge current control" and "Input current limit control".

Since now an extension of the solar plant took place, I wanted to use a Cerbo GX instead of the Raspberry Pi and do without the DA converters but regulate this purely via software. More precisely, by means of Node-red on the Cerbo GX.

But unfortunately I miss the possibility to regulate the charging current (of the Multiplus charger).

I have installed the "large" einstein- Firmware (V2.82) on the Cerbo GX and I have enabled node-red and I'm using the node-red-contrib-victron node.
Devices are: Cerbo GX, Multiplus 24/3000, BMV-700, MPPT250/60, MPPT 75/15.

The AC charger node reports "There are no ac charger services available. Please check that a ac charger is connected or try a different node." The "multi control" node has no input for charger settings too.

Question now is: How can I control the Multiplus charge limit with node-red?

Multiplus 24/3000/70-16 (Type Id 2612) FW is 209

Regards

Erich

chargerNode-RED
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I do this by just reducing the AC input current limit on the multiplus to reduce the charger output. The downside is this also reduces the AC input for AC loads causing higher inverter loads.


I’ve not found a way to tell the system to prioritize the MPPT over the Multi and keep DVCC active and everything properly connected. .


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If you install the large firmware, you can use NodeRed to control the ESS setpoint. If you use battery power as your control input instead of grid power and set a limit of 0W, the system will hold the battery at 0W till the grid is at 0W and the send all excess into the battery, once you are 5% above minimum SOC then you go back to normal ESS.


Setting low input current limit while using ESS can cause unintended/erratic behavior of the system, just FYI.

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10 Answers
mrhappy avatar image
mrhappy answered ·

Hi Erich.

I have venus large with node-red on a Raspberry Pi, and I use modbus to control the charge current on my Multiplus-II. I believe it could be done the same way in your system, with your particular IP address of course:

screenshot-2022-04-07-182531.pngscreenshot-2022-04-07-182524.png


Hope you get it working,

MrHappy


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erichabg avatar image
erichabg answered ·

MrHappy you make me happy! :-)

Thank you for this good infos!

I will try it at once!

Thanks!

Erich


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erichabg avatar image
erichabg answered ·

Hello MrHappy!

I see that there are many available modbus nodes?

Which of them are you using? node-red-contrib-modbus ?


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erichabg avatar image
erichabg answered ·

Great! It works now! I have used the node-red-contrib-modbus node!


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mrhappy avatar image
mrhappy answered ·

Wonderful! That is the one I am using, yes.

Glad I could help!


/MrHappy

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erichabg answered ·

Rejoiced too soon! As I have discovered, this only works when DVCC is active and then, unfortunately, the solar controller is also regulated down. Just that I do not want. I want to charge only from AC when it is absolutely necessary. If I set the Multiplus to "Invert Only", then unfortunately Powerassist no longer works.

I am at a loss.

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samosir avatar image
samosir answered ·

Hi,

do this with Node-Red in this way:

bildschirmfoto-2022-04-09-um-160309.pngThis changes the DVCC to Maximum charge current to 0 and the bat will only charged from the MPPT.

The VRM shows ESS #6: User configured a charge limit of zero


Hope this is what are you looking for.

Samosir



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This isn't what should happen. If DVCC max current is set to 0, it should stop charging completely. Both MPPTs and Inverter. There is something wrong with your system.
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I haven't seen this as wrong until now. The Multi does not charge the battery. Could you give me a tip where I should look for the error?

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First thing I would check is that there is coms between MPPT and GX. Make sure that is working. Then update the firmware on GX and MPPT to latest and see if that fixes it. There isn't really any erros, it is more that your mppts aren't following the DVCC commands. They should say External control.

You are using a battery that supports DVCC?

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There is a functional communication between the Gx and the Mppt (Ve.can) and its responding with External.

The battery are an pylontech stack and the Mppt is following the DVCC eg. if the pylontech reduces the carge current above a SOC of 95%.

Looks right for me.

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That's good that it is working. What GX firmware are you running?
I found in an older version that setting Max current to 0, didn't stop charging. It is fixed in the latest versions.

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V2.82-large-30, the latest from the large versions. So this is a litle behind the versions without Node-Red.

If I disable the DC feedin excess option, the Mppt follows the max current setting.

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Aww, okay. That makes more sense.
Firmware is newer than mine. Won't have old bug but maybe it is back.
I might be missing something or maybe Victron has changed somehting.


Manual does still say :
"e) DVCC maximum system charge current - Modbus-TCP register 2705

-1: No limit. Solar Chargers and the Multi will charge to their full capacity or individual configurd limits.

Any positive number: Maximum combined current in Ampere for battery charging. This limits the solar chargers and the multi, and takes loads into account. Solar chargers take priority over the Multi."


So based on this it should limit both.


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shaneyake answered ·

There isn't really a command to limit charge on the Multiplus but if you run ESS in Mode 3 then it won't charge unless you tell it to.
If you have a grid meter then you need to pass that data through in NodeRed from Meter to inverter. Then to charge you simply set the grid set point to 3000W if you want to charge at 3kw and the rest of the time you use the grid meter or set the setpoint to like 0 or 10W if you don't have a grid meter.

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erichabg answered ·

Unfortunately I need a possibility to enable/disable and control charge power of the MP without using ESS. Up to now I used a DAC controled by an raspberry pi and the charge control assistant on the MP that controls the charge current with the voltage on T-Sense. Now I have buyed a Cerbo GX and expected to do that without additional components. Pity that this is apparently not possible.
I now have the two relays from the Cerbo connected to AUX and T-Sense from the MP, controlling IgnoreAC and on/off of the charger (with the appropriate assistans). A good technical solution looks different. :-(

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Hmm... I never thought it would be limited that way. I don't use ESS but have built my own ESS-like system in Node-Red. Instead of grid feed-in or MPPT charge limitig I direct the power into mining rigs to make use of the excess.

I hope you find a good solution!


MrHappy

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I need a similar setup as I can't use ESS unless its 3-phase. Currently I don't want to setup that due to cost.

I'm currently using Node-Red for controlling the multiplus charging. At the moment I'm only limiting the input current with node-red but with power assist enabled the minimum setting is quite high.
My AC coupled solar panels on AC input seldom produce that much power.

As it seems this cant be done with node-red directly I did order a DAC for raspi to be able to limit the charging power and need to do some logic around it.

Any chance you could share some of the logic you used with DAC & raspberry pi?

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Can you explain why you can't use ESS? What are the rules exactly you are trying to comply with?

Input current limit should really not be used in fixed installations best to just set it to AC input actual current limit.

If you have the ESS assistant installed, you will have full control over the inverter via NodeRed if you set ESS to External control (Mode 3).

I am assuming you aren't using ESS and simply disconnected the inverter from grid to run loads and then rejoining when battery is low. You can do this with ESS. Just change inverter switch position from On to Inverter Only via NodeRed when you want to disconnect. Then when you want to charge set Inverter to On and disable Feed-In via NodeRed. The inverter will then connect to grid but not output any power, you can then use the grid setpoint to control how much power must be used by loads+Charger, this can be controlled in steps of 10W.

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My multiplus is not certified. I would need anti-islanding device. Also my power company does not allow to connect single phase systems even if I would get the anti-islanding devices or buy multiplus-II.

I know I could do it without their permissions but don't want to go down that route.

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Power assistant and ESS are basically doing the same thing, injecting power to the grid. Mode3 would just give you more control.

For both you probably need permission from grid operator. Only way to really run your system is to disconnect from grid when Inverter is running.

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gregoryx answered ·

Butting in here NOT with an answer... but wondering if what kwindrem is doing with GuiMods where the Multiplus can be switched to "Invert Only" might be achievable through NodeRED?

(I haven't dove into MQTT or NodeRed / Modbus with Victron yet, but lurking and reading.)

cerbo-guimods-multiplus-control.jpg


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Yes, it is called "switch position" in the V.E BUS node in NodeRed, you can do all 4 options.


On

Inverter only

Charger only

Off

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Without ESS assistant you can change that switch mode. Also you can set the input current limit.
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