WeatherTech SmartCharge monitors your batterys condition and only when necessary, uses a 4-Step charging method to keep your battery in tip-top shape. Step 1 - Desulfation (Revives)Step 2 - Bulk (Constant current charge)Step 3 - Absorption (Constant voltage achieves full battery charge)Step 4 - Pulse (Charges sent out to maintain fully charged battery)SmartCharge is an intelligent battery charger unlike others that "cook" or boil batteries unless you physically shut them off. It constantly monitors your batterys power levels and will turn on or off to maintain a freshly charged battery. SmartCharge also includes a built-in surge protector because we believe you should protect your expensive vehicle electronics just as you would your computer, television and other appliances. Installation is easy and safe as well. Our technology will not allow current to flow until the proper connection is established. We encourage you to read the user manual included in the box to properly enjoy all the features SmartCharge has to offer.