The Makita 4.0Ah 18V LXT Li-Ion Battery uses Makita's optimum charging system which produces 430 percent more runtime and 2X more cycles over the lifetime of the batteries. A 5x lower self-discharge keeps the battery cells active and ready for use even after long periods of storage, charging at any time will have no effect on the battery. Built-in shock absorbing features protect the battery and sixteen firm holding contact terminals reduce the risk of power loss/fluctuation in high vibration work environments. The battery's built-in memory chip communicates with the charger to maximize battery life using 3 Active Controls (Current, Voltage and Thermal). With no memory effect, Lithium-Ion batteries can be "topped up" at any time with no affect to battery life. Features LED battery indicator.