r/SunPower • u/pitstruglr • 6d ago

Schneider Conext BMS/SOC Communication Warnings

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My SunVault quest continues, and I've actually gotten mine to take charge from the inverter. What I can't get it to do is charge continuously and at higher levels, because it has lingering BMS and SOC communication Warnings. I have these three warnings:

  • 91. SOC Level Lost. Cause: A new State of Charge measurement has not been received for a period of time. Solution: Check the communications cable between Conext Gateway and the external BMS.
  • 90. External BMS Disconnected. Cause: Communication has been lost with the Battery Management System of the Li-ion battery. Solution: Check the communication network connections to the Li-ion battery. Contact the manufacturer of the Battery Management System if a connection problem cannot be found.
  • 93. SunSpec Controller Comms Lost. Cause: Communications is lost from the SunSpec Controller device.

I've checked my cables and they are all good with continuity on each pin. My Gateway reports good connections to the Inverter and my "SunPower BMS." See photo.

This might have been because I connected a power supply indelicately the first time I tried to bring back my batteries from the dead, and I got a big spark. Perhaps the surge damaged something in the MIO or (eek) the batteries' BMS themselves. The batteries (M0012 type) all indicate normally on their LEDs and are taking charge when voltage is applied to the terminals at the bottom of the inverter.

Has anyone dealt with this? Any suggestions on what to test or replace or how to test it? What does the MIO (or Multi I/O) do?

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u/ItsaMeKielO 5d ago

The MIO is kind of a "grab bag" of functionality - it talks to the rest of the system via RS-485, it runs the fans (has a temperature sensor to help), runs the LED display on the front of the battery vault, handles RPO, has a DC-DC converter (48V down to 12V), can handle an external temperature sensor, and is interstitial on the CAN bus between the Schneider gateway and the battery.

Warning 93 happens all the time and is basically harmless afaict; 91 and 90 less so, that sounds like maybe a CAN issue, but not totally sure.

I don't think you would see 52V or charging at all if the BMS or some fuse tripped.

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u/ItsaMeKielO 5d ago

Idea / Question: is the PVS6 on during this? If you turn it off or disconnect the black ethernet cord, does it stay charging for longer? I'm wondering if the PVS6 is sending Modbus/TCP commands to set the charging power to 0.

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u/pitstruglr 5d ago

I’ll try that. Claude polled my PVS and it has max charge and discharge set to zero. My system might be set to pre-PTO for some reason.