The Makita 18V LXT(TM) Lithium-Ion battery charges faster and works longer than standard lithium-ion batteries, giving you and your cordless tools unmatched performance and productivity to take on the most demanding applications. The Makita 4.0 Ah battery combines more run time (35% more run time per charge than the Makita BL1830 battery) with a category-leading charge time of only 40 minutes, so it spends more time working and less time sitting on the charger. For added convenience, it also features an L.E.D. charge level indicator to monitor battery charge. The 18V LXT(TM) 4.0Ah battery (BL1840) is compatible only with Star Protection tools, indicated by the Star Symbol™ and/or Yellow Battery Receiver under the tool. Makita 18V Lithium-Ion batteries resist self-discharge so they're ready for use even after long periods of storage. The Makita Rapid Optimum Charger (sold separately) is a smart-charging system that communicates with the battery during the charging process to m