CTEK (56-158) MULTI US 3300 12 Volt Fully Automatic 4 Step Battery Charger Unique 4 step charging system with a patented program that tests battery condition and, charges and maintains to ensure maximum battery life and performance No sparks, short-circuit proof and reverse polarity protected makes it safe for all the vehicles electronics and easy to use Water and dust resistant means it is safe to use in all climate situations Connect and forget, no need to disconnect battery from the vehicle when charging