0-4.5 Amps charging power, this is the IDEAL all in one tool to care for 12v Batteries. The Optimate will diagnose, recover, charge, test, and maintain your batteries automatically. The Ampmatic microprocessor actively adjusts charge current to match battery characteristics to achieve a complete charge in the shortest possible time. Features a short circuit/dead cell check that detects internal damage in a battery, and prevents unnecessary charging of a battery that can not be recovered. Recommeded for standard ( with removeable caps), sealed AGM ( absorbed glass mat), and sealed Gel 12v lead -acid batteries from 8Ah to 120Ah. Will safely maintain battery at 100% never overcharging. Includes safety features such as reverse polarity protection, and no spark cnnection.