An electrical generator transforms mechanical force into electrical current through a process called electromagnetic induction. In plain English, an internal combustion engine rotates a shaft that generates electricity using an armature and stator. Generators are powered by gasoline, liquid propane, or diesel fuel. Most functions in your RV do not require a generator. Lights, pumps, your RV refrigerator, furnace, and most electric motors, operate on 12-volt DC power through your house battery. Certain appliances like your RV air conditioner, microwave oven, and most televisions do require a generator or external power connection to operate.If you plan to camp for an extended period with no exterior power source (think days), a built-in or portable generator will be useful to charge your RV’s house battery/s.  Solar panels are also an alternative to a generator for this purpose.