METHOD FOR ESTIMATING DIRECT CURRENT INTERNAL RESISTANCE OF BATTERY

The invention presents a method for estimating a direct current internal resistance of a battery, which defines a depth of discharge detection interval including a first threshold and a second threshold. When the battery is discharging, a currently battery voltage are periodically measured, a currently depth of discharge is calculated, and an open-circuit voltage is queried. The currently battery voltage is subtracted from the open-circuit voltage to obtain a voltage difference. The voltage difference is continuously accumulated to obtain a currently accumulated voltage difference. The currently depth of discharge reaches the first threshold or the second threshold, the currently accumulated voltage difference is a first accumulated voltage difference or a second accumulated voltage difference. A difference value between the first accumulated voltage difference and the second accumulated voltage difference is divided by a discharging amount in the depth of discharge detection interval to obtain the direct current internal resistance.