Whether you have a modern car with sophisticated electronics that constantly drains the battery, or you are storing any type of vehicle for extended periods of time, you're going to need our Battery Manager III. Leave your vehicle unattended for 2-4 weeks? Keep that up and you'll be replacing a very expensive battery in no time. I went overboard in redesigning the Battery Manager III. It's really trick. So sophisticated is the micro-chip technology, you don't have to worry about a thing. It even has a "desulphation mode" that sends an electrical pulse to help revive sulphated batteries that were dying! Performs its magic on any 12-volt lead-acid battery, even gel-cell batteries used in motorcycles and boats! The water resistant housing allows the Battery Manager III to be used indoors or outdoors. (Notice I didn't say underwater, though we tested it that way!) The magnetic base allows you to mount it inside the engine compartment if desired. Even if you didn't know the red lead is supposed to be hooked up to the positive terminal, a built in electrical detector would prevent sparking and the warning light glows if the polarity is crossed. There are two choices for hooking the unit up to your battery: simple alligator clips, or permanent rings with a quick disconnect plug. I like the "quick disconnect" option so when I'm done with my occasional Sunday drive, I simply plug the leads up and go! This is not your typical "trickle charger" you've seen elsewhere. This device is designed to keep batteries at full charge without overcharging or boiling out battery fluids. Additional 29 1/2" long quick disconnect accessory cables are available.