A rack power unit is configured to be inserted into a device rack of a data center. The rack power unit includes one or more power supplies and one or more battery packs. The one or more power supplies are each configured to receive power (e.g., AC power) when the apparatus is in the device rack, and convert the received power to a DC power. The one or more power supplies are further configured to output the DC power to a DC power bus of the device rack. The one or more battery packs are each configured to provide, in response to an interruption in the received power, DC power to the DC power bus of the device rack.