Let's say, for example, that I have a common household item that is 6amps, being run from a 12v circuit, like a car battery. That would make the wattage 72, correct? What is the time frame on that? Is that 72 watts an hour? a minute? Basically, how do I convert that number, 72watts, into a kilowatt hour? I'd like to know basically, how many kwh come from the typical car battery, in a comparison for class. Thanks!