Why is the generator cycling??

Running the generator this morning. I have the frig on gas. Running a small 110 house fan. HWH is on gas. TV is on as well as the direct TV box. Other then that nothing else is on except the hidden devices. What is cycling causing my generator to fluctuate in speed and my amps to vary from 2 up to 16amps? Batteries were low (12V) when I turned the generator on this morning. I don't understand what is turning on and off to change the load on the generator.