A portable power transfer device has input connectors and output connectors which can be used to transfer power from a first electronic device to a second electronic device. The connectors are housed in a main enclosure, which also has an auxiliary USB port. An internal power source is also housed in the main enclosure. The second electronic device can be charged through an output connector or a USB cable connected to the auxiliary USB port by draining power from the first electronic device or from the internal power source. A voltage regulation circuit is electrically connected between the input connectors and the output connectors, as well as between the auxiliary port and the input connectors. The voltage regulation circuit ensures a desirable output voltage. In addition to power transfer, the power transfer device enables data transfer when using USB connectors and ports to connect the first electronic device and the second electronic device.