DeWALT 4A Professional Charger/Maintainer. Microprocessor technology gives this 12V car battery charger the power to charge most 12V batteries including deep-cycle, gel and AGM batteries. Fully automatic microprocessor control feature adjusts the amperage rate to charge and maintain batteries quickly and safely with one press of a button. High frequency current pulse can be used to recondition car batteries that are weak, sulfated or deeply drained. Microprocessor control adjusts current to match battery type and condition. High frequency technology is over 20% more efficient and over 50% lighter than conventional charging systems. Winter mode for specialized battery charging in winter weather conditions. Large easy-to-read LCD display shows full range of readouts including voltage/amperage, charge capacity and includes "bad battery" indicator. Automatically switches to maintenance mode when battery is charged.