The AL 1820 CV charges Bosch Li-ion slide-on batteries between 7.2V and 24V. The AL 1820 CV charger ensures a long battery life. The flashing indicator shows you when the charger is charging. The continuous light indicates that the battery is 100% charged or warns you if the temperature of the battery is outside of the permitted temperature range. Charge time is generally between 45 and 80 minutes dependent on the Ah of the battery. The AL 1820 CV is compact and lightweight to fit neatly into a toolbox.