I've been an RV technician for a long time. It always amazes me that RV dealerships don't do a good job educating new buyers on the basic systems in their new rv. So many people have bad experiences and end up spending money to call in a mobile rv tech to solve a problem, or get them out of trouble that could have been easily avoided.
Let's start with the electrical system. 50% of what I do as a mobile tech ends up being related to an electrical problem, in one way or another. Too often, poor training is the reason.
The battery (or batteries) is the heart and soul of your electrical system. You must have a good battery to have a good rv experience. Most of your lighting, and on board systems, such as water pump, furnace, and yes, even most air conditioners, rely on good battery voltage to operate properly. Many have asked me..."why does it (battery) matter, if I'm going to be plugged in at my campsite?". To which I say, if your battery is more than a couple of years old, you run the risk of it drawing so much current from your converter, that it can overheat and fail. Then you will be buying a battery AND a converter...and possibly a service call from a guy like me. Batteries actually short out, internally when they get bad enough. Remember, just because the battery in you Dad's Buick lasted for 7 years, doesn't mean your rv battery will. I only count on my batteries to last 2 years.