The Battery Backup Unit (BBU) unit will allow you to retain the information that has not been written to the disks yet. In case of power failure/outage the RAID controller will complete the write cycle upon the next power on.
How long ago did you purchase this system? Remember that Intel server products carry a 3-year limited warranty.
The battery is unavailable as a separate item. The ordering code for the replacement part is AXXSCM3S. This ordering code is for the storage controller module.
You may contact one of our Intel Resellers to check product availability.