If a gasoline generator produces alternating current then how can it be called a generator?

Generators aren’t widely used anymore because brushed DC motors wear out relatively quickly, produce sparks and are noisy.

Generators produce direct current using brushed motors, pre 1960s cars had generators. Modern cars produce alternating current with brushless AC motors which is run the through a diode bridge to produce DC current.

Sciencing: DC Generator vs. Alternator

In some ways its kind of ironic that cars use alternators and not the term generators because they ultimately produce DC power after rectification. But auto makers aggressively marketed the term alternator in the 1960s as they were superior in many ways to generators. Alternators are driven by voltage regulators, they have precise control over the output voltage so idling a car with the headlights on doesn’t discharge the battery. And the solid slip rings are so much more reliable than brushed motors.

My grandfather told the story about how he drove to Watertown after dark by the moonlight with his headlights off during the call for war during World War II, because his generator was worn in his car and it couldn’t keep up with the load. Stories like this were not uncommon in the days before alternators. Headlights and tail lights were much smaller and dimmer compared to modern cars too because the generators could only output a few amps at 6 volts DC – so you might have only had fifty or 100 watts at most to provide all power to the vehicle. Nothing like the 1,400 watts or more a modern 100 amp alternator can provide.

To be fair, generators do generate power. But it still would be a lot more accurate to describe gas generators as gas alternators.