You can get just the battery: [URL] Replacing the battery should be documented in the manual, but there isn't much to it.  Power off, unplug battery (there is a small connector on the controller card), replace battery, plug in battery, power on. 
Hi, I have a PowerEdge 840 with a PERC 5/i Adapter controller. It recently pop up an alert: Storage Service  The controller battery needs to be replaced.: Battery 0 Controller 1 Plus another system voltage warning: Instrumentation Service  Voltage sensor detected a failure value Sensor location: BMC ROMB Battery Chassis location: Main System Chassis Previous state was: OK (Normal) Discrete voltage state: Bad I think the voltage problem is related to the battery. Is there any way I can order the new battery for the replacement? And is there any manual that I can follow to replace the battery. I don't even know where is the battery located. Please comment and please help!! Thanks! Steve
PERC 5/i Adapter needs battery replaced...Please help