Rated capacity indicates the maximum amount of electricity a portable power station can store in its battery when fully charged. . The Power Station: This is the box with all the plugs. It's a big, smart battery that stores electricity. Think of it like a rain barrel. We break down the concepts behind the numbers one by one — and explain why you should care. But what does it mean? How should you relate watt hours to what the battery generator can really do? Well, I'm going to help you with that. It is divided into different sections, such as whole-house, kitchen, RV. . A kilowatt (kW) is 1,000 watts and is a measure of how much power something needs to run.