The CHFC3 Universal NiMH Battery Charger from Energizer has four bays to charge AA, AAA, C, and D batteries as well as two bays to charge 9V batteries.  Once the batteries have reached full capacity, the Delta V has a safety timer that shuts off to prevent the batteries from overcharging. The universal charger has short circuit and reverse polarity protection, and a solid green LED indicates the batteries are charging. The LED will flash if a bad or primary battery is detected and won't charge the battery.