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Pylontech BMS / BMV 712 / One Cerbo - Can They Work Together ?

Dear Experts

I have a small issue with my back-up system.

I recently upgraded my installation from lead-acid to a 21kWh Pylontech system.

Everything is running well and I am very pleased so far.


However, since the main system runs our off-grid house I also installed a little 24V backup system with my old lead-acid batteries, two 220W panels in series and a 75/15 MPPT smart charger.


I also wanted to use my old BMV 712, which I don’t need anymore, since I installed the Pylontech US3000C batteries and have them managed by its own BMS.


I connected the BMV712 as well as the MPPT to the same Cerbo (VE.direct) that my Pylontech batteries are connected to.

The BMV also measures mid-point voltage since I have a battery-equalizer installed.


The idea was to be able to monitor both systems (Pylontech and led-acid) via VRM


The problem.

As soon as I connect the 75/15 MPPT via VE.direct to the Cerbo the charger stops working. Normal voltage, but no current.(and a little warning that the charger has been disconnected for protection)

BMV712 displays battery voltage and SOC as usual

If I then disconnect the MPPT from the Cerbo and remove the “controlled by BMS” feature, in the MPPT the charger jumped back into action as if nothing happened, but of course the data is no longer displayed on the VRM


Hence my questions: Is the Cerbo capable of managing and displaying two separate (monitoring) systems or is the Pylontech BMS trying to regulate my back-up system as well, which would be an explanation for the trouble.

Any input is appreciated

Thanks




MPPT Controllerscerbo gxBMV Battery MonitorPylontech
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2 Answers
kevgermany avatar image
kevgermany answered ·

The Cerbo can only handle one monitor/BMS.

But if you reconfigure the BMV as a power meter, it will then work in conjunction with the Pylontech BMS. But in this mode you lose some functionality.

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tombe avatar image tombe commented ·

Thanks for that

The BMV shows the battery data, and displays it on VRM, that's no problem. I tried the power meter option, but it does not give me any more info than I already have. The charger does not want to co-operate.

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pwfarnell avatar image
pwfarnell answered ·

If you have the MPPT connected to the Cerbo then the problem is that the MPPT goes to "Controlled by BMS". You need it to work standalone and if you have a Pylontech BMS and DVCC set up I am not sure if you can actually remove the external control from the BMS. If you can not then you will have to run it disconnected.

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tombe avatar image tombe commented ·
Yes the setup is as you said, but I was hoping the Cerbo realises that the MPPT is controlled/linked to the BMV712. So you're saying I would need to get another Cerbo and add another installation?
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pwfarnell avatar image pwfarnell tombe commented ·

I think that you are OK to have a secondary battery bank with its own monitor but other components will always be assumed to be related to the main battery bank. Your choice is run the small MPPT independently and monitor the battery via the BMV and Cerbo without MPPT data or add another Cerbo which seems a costly solution.

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tombe avatar image tombe pwfarnell commented ·

That's what I'll end up doing , I guess. It's only a back-up system and as long as I can monitore the batteries I am happy. It would have been just too sweet, to have the charger info as well. Nevermind. Thanks for the confirmation and your thoughts. It's appreciated


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