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peter-tau avatar image
peter-tau asked

Setting DVCC Controlling BMS to None results in BMS connection lost + low battery voltage

Dear community,

My question concerns a grid-connected Victron Multiplus II system with AC and DC coupled PV. Three batteries are connected and each managed by an individual BMS. To avoid issues with BMS specific maximum charge and discharge limitations that do not take into account that multiple batteries are available, I decided to not use one of the available BMS as Controlling BMS in the DVCC settings.

However, as soon as I set Controlling BMS = None and reset BMS control in my DC-coupled MPPTs to ensure that there is no controlling BMS for the MPPTs, the Multiplus II show a low battery voltage warning which in fact does not apply. The low battery warning is cleared once I select one of my available BMS as Controlling BMS in the DVCC settings.

Reproducible, once Controlling BMS is set to None, two notifications are generated: BMS connection lost + Low battery voltage. Also reproducible, once I set a Controlling BMS, no notifications are generated upon rebooting Cerbo GX.

I could imagine that the Multiplus II still expect a Controlling BMS. Is a reboot of the Multiplus required once Controlling BMS is set to None or what else needs to be done after setting Controlling BMS to None? Does anybody has a hint as how to proceed?

Thank you all for your kind support.
Best regards,
Peter

Multiplus-IIESSBMSDVCC
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Karman de Lange avatar image Karman de Lange commented ·

Hi, Did you manage to resolve this, Mine ran fine for few days, now getting this same error


thanks

L

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1 Answer
oxy avatar image
oxy answered ·

I have a similar issue in such setup:

  • ...
  • Color Control GX
  • BMV-702
  • SmartSolar MPPT 250/85 (with tiny monitor)
  • SmartSolar MPPT 250/100 rev2 (without tiny monitor) - some time ago it started showing incorrect battery voltage (seems like a software/HW degradation issue), so I decided to try DVCC!

As my goal is to just synchronise battery voltage from BMV-702 to MPPT chargers, I enabled SVS and disabled everything else:


screenshot-2024-03-30-at-153223.png


However, as soon as I set "No BMS control", both MPPT chargers throw "Error #67 - No BMS", though both of them are now synchronising on the voltage (i.e. original problem solved).


This is annoying, and the only workaround to remove "Error #67" I found so far is:

1. SmartSolar MPPT 250/85 (with tiny monitor): disable BMS control via setting #31 in the tiny monitor.
2. SmartSolar MPPT 250/100 rev2 (without tiny monitor): via VictronConnect, save/export settings, reset settings to defaults, reimport settings.

These steps seem to force chargers into not using BMS (which maps to "No BMS control" setting in GX), but they are still synchronising voltages as needed (SVS).


Caveat: the above needs to be redone if GX is rebooted! I assume this is because during boot, chargers receive some message that there is BMS in the system, which is disabled in GX "Controlling BMS" setting, and "Error #67" is triggered again...


screenshot-2024-03-30-at-153223.png (36.3 KiB)
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