A power booster includes a voltage detection circuit, a battery charger, a rechargeable battery, and a transformer circuit. The voltage detection circuit detects a voltage of the input voltage of the power booster. An input of the battery charger is electrically connected to an output of the voltage detection circuit. The rechargeable battery includes an I/O port electrically connected to the battery charger. The transformer circuit includes a first voltage input, a second voltage input, and a voltage output. The first voltage input is electrically connected to the output of the voltage detection circuit. The second voltage input is electrically connected to the I/O port. The voltage output is used for connecting to a mobile electronic device.