A battery pack adapter system includes a device that allows different sized and shaped battery packs to be converted for use with multiple power tools from different brands. In one embodiment, a drill battery and drill are joined together through means of the battery pack adapter device. This allows the drill battery to power the drill even though the battery and drill have different configurations. The battery pack adapter device includes metal electrical connectors that extend from a top end of the device towards a bottom end of the device. The metal electrical connectors transfer the electrical energy from the battery to the power tool through by means of the adapter.