A RV battery works on the basis of a set of sheet baths in sulfuric acid. Sulfuric acid is an electrolyte and electrolytes are liquid solutions that are good conductors of electricity. Half of metal plates in a car battery consist of the substance lead dioxide, and the other half consists of pure lead. The battery has a sealed cover, as two external contacts, or services, are connected to the lead plates inside. One post is positive, other negative. Read my post here to know how a battery is specifically created for RV.
Sulfuric acid is a compound of two hydrogen atoms, sulfur atom and four oxygen atoms. In an aqueous solution, such as in a car RV battery, sulfuric acid is in an ionized state. In other words, the two hydrogen atoms are dissociated, or separated from sulfur and oxygen atoms. The sulfur and the four oxygen atoms stick together and together form a negative ion. The two hydrogen atoms in each sulfuric acid molecule run freely in the solution. They are positively charged and balance the negative charge in sulfate ion.
When the RV battery is in the charged condition and ready to deliver electricity, lead and carbon dioxide The plates are in their relatively clean form. Because electricity is called --- such as when the operator turns the key to start the car --- the sulphate ions are deposited on the lead plates and form the composite lead sulphate. This chemical process allows electricity to flow out of the RV battery through terminals or posts. At the same time, the concentration of sulfuric acid in the battery solution decreases (because the sulphate part of the acid is locked on the lead plates). The battery delivers power and discharge. And when the sulfuric acid level reaches a critically low level and lead plates with lead sulphate, the battery's ability to deliver electricity is drained. We would then say that the battery is dead.
Fortunately, this is not a permanent state. The car has a device called a generator whose function is to generate electricity and charge the RV battery. When the car engine is running, the generator is turning and sending electric currents back into the battery to charge it. Normally, car batteries are not allowed to die, as most often it is only released for a long time to turn around the engine to get it started. Then the generator takes over delivering most of the power the car needs when the engine is running. The RV battery will help a little bit if required, but is constantly charged by the generator.