The D250S charges the secondary battery using the alternator, providing a six step charging curve to condition, charge and maintain the secondary battery, increasing performance, extending its life span and saving money on unnecessary battery replacement. * Input: 22v DC 18-22A Max. * Charging voltage: 14.4v @ 25 deg.C * Maximum charge current: 20A * Six step charge output. * Suitable for 12v Wet, MF, AGM and most Gel batteries. * Current ripple: <1%* * Operating temperature range: -40 to +70 Deg.C. * Cooling: Natural convection. * Battery capacity: 40-500Ah * Protection class: IP65 * Weight: 0.7 Kg * Warranty: 2 Years