A battery discharge measurement device for determining the state of discharge for a battery has a battery voltage measurement unit adapted to measure and store a battery voltage and a battery usage activity detector for detecting a predefined battery usage activity draining current from the battery and triggering a voltage recovery period. A processor unit is provided for estimating a battery voltage of the battery during the voltage recovery period based on the measured and stored battery voltage and the number of predefined battery usage activities detected since the battery voltage measurement unit measured the battery voltage of the battery.
