The Optimate battery charger is completely automatic, safe and simple to use. The advanced 3-stage charging program features both constant current and constant voltage charging to completely and correctly charge a variety of battery types. The Optimate will also properly maintain a battery at it´s correct voltage during storage and long periods of non-use without overcharging and gassing. The Accumate is reverse polarity protected and spark proof, and features five separate LED lights, three of which indicate a battery´s charge status. For charging and for maintaining batteries up to 55ah. Comes with ring and clip style cables with a quick disconnect.