Makita BL1830 18v 3.0AH Battery. This 18v 3Ah LXT Lithium-Ion battery and optimum charging system produces 280% more lifetime work with 2x more cycles. It has 5x lower self-discharge, keeping 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. 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, Thermal). STAR Protection Computer Controls allow the tool and battery to monitor conditions and exchange data in real-time to protect against overloading, over-discharging, and overheating. Overload protection cuts power when the tool is put under abnormally high current draw. Over-discharge protection monitors battery charge capacity and cuts power to extend battery life when the battery is too low. Extreme heat is the enemy of all batteries; Makita's system protects against this.