Our 12V battery charger can automatically detect when the battery is full, it automatically converts to float charge mode,you don't have to worry about the charging time being too long to damage the battery. Short Circuit, Reverse Connection and Over Current Protection. Overload protection. Compatible with 12V 4Ah - 12V 20Ah Batteries. Easy to use. Intelligent design. Built-In Battery clips. Plugs into 2 point plug sockets.