Power conversion device

A power conversion device for portable computer, which having a housing and a power converter circuit and a charging circuit contained therein is disclosed. The power converting circuit can convert the AC external power to DC power suitable for operating the portable computer, and transfer the DC power to the portable computer through the output power line. The charging circuit is connected to the power converter circuit which provides power to the backup battery cell. Moreover, the power conversion device includes replaceable charging plug positioned in the housing, so that the backup battery for various models computers requiring different supply voltage can be recharged via these replaceable jack.