Ideal for purchase with bulk Z tools. DC18RC Lithium-Ion Rapid Charger charges 18V Lithium-Ion Compact Batteries in 15 minutes, 3.0Ah Batteries in 22 minutes and 4.0Ah Batteries in 36 minutes! Optimum Charging System incorporates 3 Active Controls (current, voltage and temperature) that provide an optimal charge and ensures batteries are not over-discharged or over-heated during the charging cycle. Central Processing Unit (CPU) in battery communicates with charger to analyze battery and charge according to its unique condition. Digital Power Display indicates condition of battery and current charge level (-80,% +80,% 100%).