....
: Yes, but more slowly, right. Don't they have speed regulators
that
: somewhat depend on the load. Cars use far less at idle than
they do
: when moving the car.
:
: Actually that would be very rare. I've never seen one that
does that,
: and I've used many of them. They usually run constantly at one
of two
: speeds: 1800 rpm or 3600 rpm. That is necessary to maintain
the 60 hz
....

No, not so rare. MANY generators idle during periods of no-load.
Most generators around here do, including mine. If there is ANY
load though, it jumps up to speed incredibly fast.

So, it depends on the particular generator design. A 5 gallon
tank of gas can last me a day during power-outages IFF I only
power the furnace & fridge. When they're all off, the generator
drops to a fast idle and stays there. It still puts out 130Vac,
but I have nothing to see the frequency with because my test
equipment triggers it up to speed. Too lazy to drag out my scope
to look at it. Just a 4W nightlight is enough to cause it to
spring up to speed.
As long as they're supplying any current though, they will
definitely be at speed, and that speed is usually governed in
some way to remain pretty stable; that's how they get the 60Hz
frequency.

I've no experience with generators that vary motor speed with
load, but I do know there are some - they've been discussed on
various groups. So I don't know how those work. I suspect
they're more DC systems than anything else.

HTH,

Pop