I want my BMS to control charging but not to provide state of charge, and there’s no way to set that up in the GUI. My rationale is that I don’t trust these DIY BMS boards with high current, so I’ve got them monitoring cell voltage and temperature, but they are not in the DC path so cannot measure SOC.
Setup:
- 2x Quattro 10kVA in parallel, Cerbo GX on v3.73
- 3x MPPT
- Lynx Shunt 1000A VE.Can
- 4x JK BMS reporting to an aggregator (iBMS) that presents the bank to the Cerbo
as a single battery on BMS-Can
The aggregator sends sensible CVL/CCL/DCL and I want the Victron gear to follow those. What I don’t want is the BMS’s state of charge. No current flows through it so it can’t coulomb count, and its SoC is meaningless. The Lynx Shunt is the only device actually measuring current in and out of the bank.
Settings > System Setup > Batteries only lets me choose a battery monitor. Pick the BMS and I get charge control plus a false SoC. Pick the Lynx Shunt and I get a real SoC but no charge control. There’s no option for the combination that is actually correct for this hardware.
The only way I found to do it was writing Settings/SystemSetup/BmsInstance directly over MQTT. That works exactly as intended and has been stable since I did it. But it’s undocumented, there’s no menu for it on this firmware, and if anything ever resets it I have no way to put it back from the GUI.
Request: Expose the controlling BMS as its own setting in the GX, independent of the battery monitor selection. Surfacing what BmsInstance already does would be enough on its own.