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BMS AP9921X-AP9922; alarms “Battery Cell Shorted”

Issue:

Product line:

Battery Management System (BMS) AP9921X-AP9922

Environment:

All models, all serial numbers

Cause:

The sum voltage of the indicated battery is below normal, usually by more than the voltage of one cell. The alarm value is calculated using the following formula: ((#Cells/Batt)-1) x (Vstring) (#Cells/Batt) x (#Batt/String) Example: A normally float-charged 12-V VRLA battery measures 13.5 V at 2.25 Volts per Cell (VPC). If the voltage falls below 11.25 V (2.25 VPC x 5 cells), but is still above 0.5 V, the battery activates the Battery Cell Shorted alarm.

Resolution:

Check the voltage reading of the indicated battery. If the alarm is accurate, replace the battery immediately.