Bicycle power supply with reduced battery leakage

A bicycle power supply apparatus comprises a battery unit 32 for storing power from a power supply and for supplying power to electrical components; a power switch 31 operatively coupled to the battery unit 32 for selectively switching power from the battery unit 32 to the electrical components; and a switch control unit 50 that receives power from the power supply and controls the power switch 31 according to the power received from the power supply.