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 GasGuageStatus: 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