Apparatus and Method for Detecting Internal Resistance of Battery

This application discloses an apparatus and a method for detecting internal resistance of a battery, applied to the field of intelligent vehicles. The apparatus includes: a processing circuit, a differential amplifier, and a charging circuit. The processing circuit is configured to input a first comparison voltage to a second input end of the differential amplifier and maintain the first comparison voltage. The differential amplifier is configured to output a first output voltage based on the first detection voltage and the first comparison voltage. The processing circuit is further configured to control the charging circuit to charge the battery by using a constant current, and detect a second detection voltage of the battery after the battery is charged. The differential amplifier is further configured to output a second output voltage based on the second detection voltage and the first comparison voltage.