How Do Car Generators Work? | It Still Runs A car generator is a dynamo. It is able to produce electricity through the rotation of tightly wound fine wires in a magnetic field. This magnetic field is maintained by a fixed arrangement of magnets or electromagnets surrounding the spinning windings of wire. Classic Car Automotive Electrical Systems - Part 2: How Classic Car Automotive Electrical Systems - Part 2: How Generators and Alternators Work GENERATORS AND ALTERNATORS. Last month's article dealt with the principles of DC electricity and how your car's battery functions. Now we can go on to how that battery gets charged. In older cars (before about 1964) this was done with a generator.