The Nitecore D2 is a smart charger with universal compatibility that allows it to recharge most all cylindrical rechargeable batteries, which eliminates the need for multiple chargers. The D2 auto detects Li-ion, Ni-HM and Ni-Cd batteries, also the smart charging circuitry selects the optimal charging mode for the given battery. Each of the two battery slots are microcomputer controlled that charges the batteries independently. The LCD screen allows the user to clearly see the charging progress, voltage, and current. Batteries are safely charged while the intelligent auto power off function will stop charging batteries once they are complete.