Abstract: The present invention discloses a method and a circuit for controlling a battery charge and supply by a microprocessor, in which a microprocessor is connected individually to a charging circuit, a DC voltage circuit, and a power supply circuit; a pair of chargeable batteries is set between the charging circuit and the DC voltage circuit such that if the microprocessor detects one of the batteries having a larger power than the other battery, the microprocessor will control the charging circuit to charge the battery having lesser power until the microprocessor detects the level of charge of the charging battery is lower than the standard electric level in order to achieve the purpose of maximizing the utility of the battery and accurately controlling the power supply through the control of the microprocessor.