Is it possible to add BBUs in the server F628R3-R72B+? If yes, please advise the reference of the support? Is it necessary to install in the slot of disk 2.5?
Please find optional Battery backup part details below:
You will need 4 of these (1x for each node) Optional kit MCP-450-00001-0N: LSI iBBU09 extension kit (to be installed at 2.5" HDD location) and BTR-0022L-LSI00279: LSI00279 IBBU09 BATTERY BKUP FOR SAS2208
The BBU needs to be installed in 2.5” HDD location. But if you are using all 8 drives (6+2) of the system, then you can install BBU as shown below:
Highlighted in RED location for BBU:

For above installation, the Battery is installed directly on chassis wall without the use of MCP-240-00094-0N. Only cable is actually needed from MCP-450-00001-0N.