2/10/20/40/100 Amp 12 Volt Smart Battery Charger Fully automatic/high frequency 12V Smart Battery Charger. Alternator voltage check. Instant engine start (Rapid Charge). Short circuit and reverse polarity protection (No Spark). Built in battery reconditioning (Desulfate). Three stage automatic rapid charging. Lightweight, high efficiency design. Cables and clamps self-stored. Charging complete indicator. 400 Amp rated clamps. Compensates for low AC from extension cord use. Microprocessor control (Digital Smart Control). High frequency power conversion technology. Heavy-duty rated, 5-yr warranty.