NEW battery protection system provides over-discharge, temperature and current protection for enhanced performance, battery cycle life and overall battery life (when used with STAR marked tool)Li-Ion batteries offer extended run time versus Ni-Cad and Ni-MH batteriesLi-Ion batteries offer more cycles over the life of the battery versus Ni-Cad and Ni-MH batteriesOptimum charging system utilizes 3 active controls (current, voltage & temperature) to maximize battery lifeBuilt-in memory chip communicates with charger CPU to optimize the charging process based on the unique conditions of each battery