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eyacht asked

Why would the SOC in my BMS be different to what is in my Victron CGX display?

Hi. I lost AC power this morning at 1.30am. No heavy loads running and the typical ambient draw at night is around 12A so a bit over 100W. The notification was a Voltage Overload error and the house bank inverter state was Fail. Turning the Quattro off and on again cleared the fault.

I have two propulsion banks, port & stbd, each with 2 x 48V/5KW inverters in parallel and a 48V/540Ah battery bank. Typically, I have one of them charging the 12V/900Ah battery bank (that has another quattro, 12V/5KW) and keeping it at float. However, I noticed the 12V bank was at 13.9V at charging at 41A with the display SOC reading 100%. I turned off the propulsion bank to stop the charge and let the 12V house bank get us through the night. All batteries are LiFePO4.

At a more sociable hour this morning, I connected to the BMS (Orion Jr) and looked at the settings, which is when I noticed SOC reading was 84% but the Victron display was 94% (about 8hrs after we lost power and I switched to the house bank). This got me wondering whether the BMS didn't stop the charge because it thought the SOC was much lower than it was despite the voltage being over the float voltage of 13.5V.

This is probably more of an Orion BMS question really (I've emailed Orion already) but I was wondering if anyone else has come across this issue of SOC differences on the Victron display and the BMS and what the solution was.

MultiPlus Quattro Inverter ChargerBMSSOC
2 |3000

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