Charges 4 AA/AAA NiMH batteries. Ensures a full charge regardless of charge or battery capacity LED Indicates Charge. Red = Charging. Green = Complete. Flashing Red = Error/Abnormal battery or abnormal temperature. Maintenance Charge Keeps batteries Fresh. International Charge Capability- device can be used worldwide with suitable converter plug. Microprocessor Controlled: Charge termination based on –dV/dt, temperature, and/or built-in timer. Over-temperature shutoff- prevents overheat of battery. Primary battery protection- will not charge non-rechargeable batteries. Low voltage battery protection- prevents overheat and damage to battery. Power protection circuit- resets whenever a battery is removed.