5.0 Ah battery offers maximum run time for prolonged, heavy-duty applications. LED charge level indicator displays approximate remaining battery power. 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 batteries. Li-Ion Batteries offer more cycles over the life of the battery versus Ni-Cad and Ni-MH batteries. Optimum charging system utilizes 3 active controls (current, voltage and temperature) to maximize battery life.