Patent ID: 8143744

Claim:
An uninterruptible power supply comprising: a battery; a first input having an input line connection and an input neutral connection to receive a first input voltage from a first voltage source; a boost circuit configured to provide a positive output DC voltage with respect to the input neutral connection and a negative output DC voltage with respect to the input neutral connection in both a line mode of operation and a backup mode of operation; a first connection circuit to couple the first input to the boost circuit in the line mode of operation; and a second connection circuit to couple the battery to the boost circuit in the backup mode of operation; wherein the uninterruptible power supply is constructed and arranged to isolate the battery from the input neutral connection in the line mode of operation and wherein the uninterruptible power supply is configured to operate with an AC voltage source at the first input having a peak AC voltage that is less than the positive output DC voltage, and wherein the battery has a battery voltage that is less than the positive output DC voltage and greater than the peak AC voltage.