According to Rob S :

Years ago in Country Life (Canada) or Harrowsmith magazine I saw an
article on modifying your cars alternator to provide AC current. In this
case it was to provide for power tools on a farm when something broke
out in the fields.

Years ago Northern Hydraulics used to sell an alternator modified to do
just that.

HOWEVER, you have virtually no control whatsoever about AC frequency -
indeed, I think the windings are set up for frequencies considerably higher
than 60hz for efficiency reasons.

A generator of this type would work just fine to run portable
power tools (which are virtually all universal motors - brush type,
they run on DC and AC) as long as the voltage was reasonable.

But this wouldn't work at all properly for an induction motor which needs
frequencies very near to 60 hz. Most motors for stationary devices (water
pumps etc) are induction motors.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.