Just watched this video on YouTube regarding setting up a Mobile Office. This guy shows you how to setup your office using a separate battery in the trunk vs. using your car's internal battery under the hood. He also shows you how to use the internal battery, if you want to set things up that way. The only thing he doesn't show is the installation of a circuit breaker when using the car's internal battery. It's a long video because the guy who's doing most of the talking evidently likes to hear himself talk.