Abstract: A power supply device includes at least one virtual battery connector installed at an end of the electric output line, an anode and a cathode, such that the power adapter can convert an AC power into a DC power, and transmit the DC power to an anode and a cathode of the virtual battery connector through the electric output line. If the virtual battery connector is installed into a battery compartment of an electric appliance, the virtual battery connector will be able to substitute a battery generally available in the market for supplying the DC power to the electric appliance. The way of using the virtual battery connector as a power supply interface of the electric appliance not just reduces the battery consumption substantially, but also achieves the environmental protection effect.