The world's most advanced fully automatic 12V battery charger with T compensation! OptiMate 7 saves batteries other chargers can't, because it recognizes the difference between a discharged battery that needs charging and a dead flat sulphated battery that needs saving. Perfect for months-long maintenance of any size 12V lead-acid battery - deep cycle, automotive, marine, motorcycle . "Multi-stage desulphation: Restores neglected batteries from as low as 0. 5 Volts. Ampmatic charge control: adjusts current to suit any battery size (3 to 400Ah) OR condition for fastest and most complete charge. Cell voltage balancing mode: correctly prepares NEW batteries for first use and optimizes battery performance. Daily battery condition tests & interactive float charge: maintains battery fully charged, weeks or months long. "