Patent ID: 7495415

Claim:
A DC backup power supply system for supplying DC power to a load, comprising: an AC/DC converter for converting AC power to DC power; a DC/DC converter coupled to an output of the AC/DC converter for converting the DC power to DC power to be supplied to the load; and at least one DC backup power supply unit which includes a battery to supply backup DC power; a charge-discharge circuit for controlling an output of the battery; and a control circuit for controlling the charge-discharge circuit; wherein the battery, the charge-discharge circuit and the control circuit are electrically connected and arranged so as to form the DC backup power supply unit as a single unit; wherein the DC backup power supply unit is connected via a detachable connector in parallel to a path from the AC/DC converter to the DC/DC converter at a connecting point between an output of the AC/DC converter to an input of the DC/DC converter and the input of the DC/DC converter, without a transformer between the DC backup power supply unit and the input of the DC/DC converter, so as to supply the backup DC power to the load through the DC/DC converter and to receive the DC power from the AC/DC converter via the path and the connecting point, and is configured so that the DC backup power supply unit is detachable while the load is maintained operational without interruption of DC power supplied from the DC/DC converter; and wherein the battery has a number of battery cells, cylindrical portions of the battery cells are laid on an approximately horizontal plane, and the battery is accommodated in a space having a height corresponding to one unit (1U) size of a 19-inch rack.