In any modern RV, the generator does not charge any battery, it provides 110-volt power to the on-board Inverter/Charger or Converter/Charger.
The generator also provides 110-volt power for the house air conditioner(s), microwave oven and other 110-volt devices when not connected to shore power.
What is the most common problem with a generator? If your generator is running but you are not getting 110-volt power into the RV, the first thing to check is the circuit breakers on the generator. There may be one or two. If there are two, they are usually right next to each other, so you don’t have to look all over. It is a good idea to find the circuit breakers so that you will know where they are BEFORE the occasion occurs that a circuit breaker trips. You may be surprised to learn that the circuit breakers on most generators are not labeled “on” or “off”, so you can’t tell which way to move the switch to reset it. Yes that sounds stupid, but that is just the way it is. How can you tell which way is “on” and which way is “off”? It is a secret! No, seriously, here is how you can tell: Move the circuit breaker switch back and forth. You will be able to feel a stronger resistance due to spring tension as you move the switch one direction, and no resistance from spring tension as you move the switch in the other direction. The direction that you feel resistance from spring tension is the direction to move the switch to reset the circuit breaker to the “on” position.
The second most common failure of a generator if it has a gasoline engine is a bad carburetor. Modern gasoline usually has some ethanol in it, which attracts moisture and combines to make a nearly insoluable gum in the minute passages in the carburetor. Or the ethanol causes the metal in the carburetor to corrode, which blocks the passages. In the “old days”, carburetors could be taken apart and cleaned. Nowadays, the gum cannot be cleaned with available solvents or the corrosion cannot be cleaned out of the minute passages. If a carburetor is bad, it is usually most cost effective to replace is than to spend the labor to attempt to clean it and then find that it still is bad. The question you want to ask is: How do I keep my carburetor from going bad? The answer is simple: Run the generator for ½-hour every week so that the fuel does not rot and turn to gum in the carburetor. If you have a generator with a diesel or LP powered engine, then this problem will not occur. However, it is still advisable to run your generator under load every week (or at least try to do it once a month). What is a “load”? A load is a significant electrical demand, such as an air conditioner running.
To prevent costly failures of the generator, it is important to follow the instructions for oil changes and other maintenance listed in the owner’s manual. If it is a diesel generator with a radiator, it is extremely important to change the coolant (antifreeze mixture) according to the instructions in the owner’s manual, because if you don’t you may have corrosion in the cooling system which will cause overheating or leaks.