Checking on the status of your raid cards battery backup unit (BBU) is a simple process by using the following MegaCli command:

$ MegaCli64 -AdpBbuCmd -a<adapter#/ALL>

In the following example we have a single controller present and will pass the -a0 argument to select the controller.

[root@localhost ~]# MegaCli64 -AdpBbuCmd -a0
BBU status for Adapter: 0
BatteryType: iBBU
Voltage: 4075 mV
Current: 0 mA
Temperature: 25 C
Battery State: Optimal
BBU Firmware Status:
Charging Status : None
Voltage : OK
Temperature : OK
Learn Cycle Requested : No
Learn Cycle Active : No
Learn Cycle Status : OK
Learn Cycle Timeout : No
I2c Errors Detected : No
Battery Pack Missing : No
Battery Replacement required : No
Remaining Capacity Low : No
Periodic Learn Required : No
Transparent Learn : No
No space to cache offload : No
Pack is about to fail & should be replaced : No
Cache Offload premium feature required : No
Module microcode update required : No
Fully Discharged : No
Fully Charged : Yes
Discharging : Yes
Initialized : Yes
Remaining Time Alarm : No
Discharge Terminated : No
Over Temperature : No
Charging Terminated : No
Over Charged : No
Relative State of Charge: 100 %
Charger System State: 49168
Charger System Ctrl: 0
Charging current: 0 mA
Absolute state of charge: 100 %
Max Error: 2 %
Battery backup charge time : 48 hours +
BBU Capacity Info for Adapter: 0
Relative State of Charge: 100 %
Absolute State of charge: 100 %
Remaining Capacity: 1213 mAh
Full Charge Capacity: 1213 mAh
Run time to empty: Battery is not being discharged.
Average time to empty: Battery is not being discharged.
Estimated Time to full recharge: Battery is not being charged.
Cycle Count: 2
Max Error = 2 %
Remaining Capacity Alarm = 120 mAh
Remining Time Alarm = 10 Min