In a 12V System with 3x E&J CAN batteries in parallel, connected to Cerbo over CAN BMS, the batteries command wrong / to high CVL 14.8V. With this I get high cell and high battery voltage.
So far so bad.
In my eyes, if I don’t switch on DVCC, the Battery BMS CVL should also not control MPPT, Orion XS, MultiPlus-II. (MPPT shows external control, what indicate DVCC / CAN BMS control is happening and high cell / battery voltage happens)
If I switch on DVCC and select “No controlling BMS” I see the same happening. (MPPT in “external Mode” even I did reset it etc. and high cell / battery voltage)
So why is there a function of “No controlling BMS” but CVL is still used from BMS and not the programmed setting of each device?
Why do I have to switch on DVCC first, to than select “No controlling BMS” to have no controlling BMS? Should this not automatically be set, if DVCC is off?
The best, even I switch on DVCC and set "max charge voltage to 14.1V, I get high cell and battery voltage (14.5), so it seams in some way that the CAN BMS CVL is coming trough, but with 14.5V not really clear what happens.
I tried to get Infos about DVCC and the BMS control from Victron but did not succeed.
With most CAN controlled batteries, subject to the protocol, Victron MPPT’s add 0.4V (for 48v systems) to the CVL in order to allow export of excess solar.
I’m not sure if this still occurs when ESS is not selected - I haven’t had the opportunity to check this.
Also, when a CAN BMS is detected, usually DVCC is forced on and can not (and should not) be turned off.
Using the “limit max charge voltage” option in the Cerbo will override the Max DVCC limit sent by the BMS - the cerbo will take the lower of the limit you set or the CVL supplied by the BMS. However, the MPPT’s may still add the offset (either 0.1V/12v or 0.4V) to this value.
I’ve not seen the ‘No controlling BMS’ option, but would not use that…
I dont have a controlling BMS. The setting is right down at the bottom. I adjust DVCC based on voltage using Node-RED. It’s insane how many people are on this forum with BMS control issues.
The real issue here is that you don’t have communications with your batteries’ BMS system.
You really need this to get at the Cell voltages, which is what should control the DVCC. 'No controlling BMS means that the Cerbo can’t find the data it needs for the DVCC function.
Perhaps instead of tryiong to use DVCC, you should try sending the voltage limits from your node red flow direct to the dbus service of the device you are trying to control: either the inverter or the mppt?
But if you use ESS the solar is not throttled. This is my flow to control the charge current. I filter the voltage and range the charge current from 20-100 amps between 10:30 AM and 4:59 PM. Outside those hours the charge current is 0, so the solar starts charging in the morning. None of my batteries on my 12V system can communicate. When the voltage rises from 13.6V to 14.2V the output changes from 100 amps down to 20 amps. You can set this to what you need to make sure you don’t get a battery going to cell high voltage disconnect. Once you have it all dialled in it works really well. I only charge to 14.2V, and in the BMS app, I can see that the voltages do not go over 3.5V per cell. When the battery is 99% full I drop the charge current to 2 amps for balancing.
I only have a 360AH battery and 200W of solar on my 12V system ATM. In summer, I will have 800W of solar and about 10kwh of battery.
Thanks a lot for your effort and answers. Also the idea of the NodeRed regulation. Definitely a idea to consider anyway.
I see I forget some system Infos.
→ Its not a ESS, its in a vehicle
→ So no rise in voltage due to feedback attempt
→ The Batteries have internal BMS with charge / discharge FET’s, so no communication mandatory
→ DVCC is not forced ON as this will come over CAN, but would make sense if the datas are correct. But if not, I need to switch is OFF reliable, so the device settings are used.
→ I would be happy using “No controlled BMS” and use the device set charge curve.
But this unfortunately don’t work.
I have done multiple systems with different CAN BMS ect. No problem at all, probably because the datas have been accurate and usable. Thanks again.
