Cell under voltage protection only works when powered on

Battery Management
1

Good day gents,

I have finally had more time to test and seems the cell undervoltage protection only works if the bms was off and powered on, there is no call to disable discharging when the cells reach below a preset value .
Im uncertain why this is but i have only discovered it recently, with serial monitor the board is posting correctly .
Serial interface started. Time: 1068
NumCells: 8, voltage: 25745 V
checkStatus() = 0
Umin = 3214
temperatures[0] = 225
checkStatus() = 0
Umax = 3222
temperatures[0] = 225
Enabling CHG FET

After such time i run a test with the following variable in place for main.cpp config .
BMS.setCellUndervoltageProtection(3210, 5); // delay in s

cells reach 3150 and still the bms does not disable discharging .

powering off the unit and on again seems to then disable the dschg fet … but not while running ?
Am i missing something ?
thank you for assistance in advance.

2

That’s strange. Normally it should definitely switch off during operation as soon as a cell reaches the undervoltage limit and not only after a reset.

I’ll try to check end of this week with my BMS. Let me know if you found out the reason in the meantime.

3

ive just done some more testing, if the value of the undervoltage cut off is set to 3140 as was in my case the voltage cut off was not implemented . and the bms would continue to provide power . However if the voltage cut off was set to 3100 then the bms would not allow lower then this value ? Seems odd ? maybe something to do with ADC? i cant think of any thing else as this is a odd number unlike using a low voltage value of 2600 for lifepo4 !
Never the less you can replicate and advise your thoughts .