The Makita BL1850 5.0ah 18v li-ion battery lithium ion 5 amp LXT uses and optimum charging system that will outperform previous Makita li-ion batteries like the BL1830 BL1840. This is a twin pack of the Makita BL1850 5.0ah batteries. LXT Lithium-Ion battery and optimum charging system produces 280 percent total lifetime work with 2x more cycles. 5x Lower self-discharge keeps 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. Battery's built-in Memory Chip communicates with the charger to maximize battery life using 3 Active .