Connecting 30 amp cord to 15 amp circuit



I just pulled our 1984 Airstream home and wanted to connect the 30 amp plug to power the lights and charge the batteries. I bought a adapter that allowed connection of the 30 amp male plug to connect to the 15 amp female end of an extension cord. I tried turning the lights on but they kept cycling on and off every 5 seconds or so. I could here a clicking noise near where the batteries are located at the front of the trailer while the power cycled on and off. The refrigerator came on and seemed to be running continuously. I would appreciate some input on why this occurred and maybe guidance on connecting to power when a 30 amp outlet is not available. Thanks