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Kees Oomen avatar image
Kees Oomen asked

Set MaxChargeCurrent to 0 within node-red works, but it gets overridden everytime. Why?

I am buidling a flow in node-red to disable charging in my MultiPlus 2 with a custom input node on path /DC/0/MaxChargeCurrent. This works well, when set to 0 the MultiPlus 2 stops charging. However, this setting gets overridden/set by another input somehow. I think it is something internally configured in Cerbo/Multiplus logic where the MaxChargeCurrent is set to 120 again. It get reproduced everytime the MPPT solar charger starts to get high voltage on the PV panels and then somehow MaxChargeCurrent from the Multiplus is set from 0 to 120. Any idea what the logic is here and how I can prevent this from happening?


Multiplus-IIMPPT ControllersNode-RED
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nickdb avatar image
nickdb answered ·

The Cerbo will be controlling this remotely via DVCC and following the batteries instructions (assuming it is a managed battery).

Trying to directly set it on the Multi will just get overwritten as it is conflicting with external control.

You'd be better off setting the DVCC parameter on the Cerbo instead, unless you are exporting, in which case it is ignored anyway.

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Kees Oomen avatar image
Kees Oomen answered ·

If I set max charge current to 0 via DVCC then it will also stop charging my battery through MPPT I think?

This is why I want to limit it on only the multiplus.

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Kees Oomen avatar image Kees Oomen commented ·

Also, in the DVCC manual it states:



  1. In all situations, the maximum charge limit configured in a device itself, i. e. the Charge current limit set with VictronConnect or VEConfigure for Orion XS DC-DC battery chargers, MPPT solar chargers or inverter/chargers will still be in effect. An example to illustrate this: in case there is only an inverter/charger in the system and in VEConfigure or VictronConnect the charge current is configured to 50A. And on the GX device, a limit of 100A is configured, then the working limit will be 50A.


So in that case the multiplus setting should not be overruled by dvcc?


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suttridge avatar image suttridge Kees Oomen commented ·

Hi @Kees Oomen

As suggested by @nickdb , your correct point-of-control (provided you have DVCC enabled) according to the document CCGX-Modbus-TCP-register-list-3.20.xlsx is :-

/Settings/SystemSetup/MaxChargeCurrent

This is also equivalent to the ModBus register 2705.

The way it works is the actual charge current will be the smallest of all the charge currents configured on all devices, so if you have one device with a 100A current limit, another device with a 50A current limit, and the DVCC max current limit is set using the point-of-control above to say 10A, then the actual charge limit will be the smallest one, i.e. the 10A.

Set this point-of-control to zero, and it effectively disables charging. I do this all the time by varying this point-of-control for finer control over the charging rate of my batteries, depending on my load conditions. I believe the new dynamic ESS (DESS) also does this.

Regards, Steve.

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Alex Pescaru avatar image
Alex Pescaru answered ·

Hi @Kees Oomen

Try to look over the logic of DVCC studying, inside Cerbo's OS, the /opt/victronenergy/dbus-systemcalc-py/delegates/dvcc.py script.

There you will find how the current is shared among devices and how the limits are handled.

It will be worth the effort... Have fun!

Alex

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Kees Oomen avatar image Kees Oomen commented ·

Thanks very helpful to even deep dive


One thing I read here.

This RAM part of multiplus is interesting, because if I set the MaxChargeCurrent path to a value and reboot the multiplus then the value is reset again.


But even without the restart, can it be that the RAM gets overwritten sometime as my value also got reset without restarting....


        # Write the remainder to the Multi.
        # There are two ways to limit the charge current of a VE.Bus system. If we have a BMS,
        # the BOL parameter is used.
        # If not, then the BOL parameters are not available, and the /Dc/0/MaxChargeCurrent path is
        # used instead. This path relates to the MaxChargeCurrent setting as also available in
        # VEConfigure, except that writing to it only changes the value in RAM in the Multi.
        # Unlike VEConfigure it's not necessary to take the number of units in a system into account.
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pwfarnell avatar image pwfarnell Kees Oomen commented ·

I successfully used the custom output node disabling my Multi charging on the path/DC/0/MaxChargeCurrent for a while on a lead acid battery system without ESS / DVCC or managed batteries. I did notice one odd thing about how it worked, namely that the Multi had MaxChargeCurrent set to 0 and was not charging but when I pulled the settings off the Multi via VRM I found the charge current was still set to 90A. This use of RAM only setting explains why I was seeing the dual nature.

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manuele avatar image
manuele answered ·

Hi everyone,


I also use this Node-Red parameter and I tell you that I have never had overwriting problems.

However, since I moved from version 3.22 to 3.30, this is where my problems started...

I wonder if this is intentional or a bug in the latest version.

It was very convenient as a manually operated option.

I have two MPII 5000 in parallel and I always set the value 2, while now it is overwritten with the maximum value after a variable time, from a few seconds to a maximum of a couple of minutes.


This has become a big problem for me!


Best regards


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vicfan avatar image vicfan commented ·

Same issue here after updating to Cerbo FW 3.30. Before it was running fine for months.

This is also a big issue for me, as I optimize the battery charging behavior through my own home control system (FHEM with SolarForecast) depending on the radiation forecast so that the SmartSolar does not shut down as soon as the battery is full (zero feed-in of the Victron system).

Also on the SSH console with dbus-spy -> com.victronenergy.vebus.ttyS4 -> Dc/0/MaxChargeCurrent the behavior is identical. A manually set value
is automatically overwritten with 105 (3 x MPII a 35A default) after a short time.
I assume an error in the FW that ha to be fixed by Victron.

best regards



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