On Tue, 26 Aug 2003 07:12:47 -0700, Eric R Snow
wrote:

If a motor is used as a generator will it put out about the same
wattage as it consumes when used as a motor?
Thanks,
Eric

Only if it's 100% efficient. The simplest case to look at is a low
speed permanent magnet DC motor where the armature resistance is the
major loss component.
With an 80% efficient motor, 20% of the input power is lost in
armature resistance. Operated at the same speed as a generator, 80% of
the original motor input power is available as generated output.
However it now has to travel through the armature resistance before it
reaches the output terminals and this loses a further 20% of the
available power.
For the same internal heating, an 80% efficient machine used at
the same speed as a generator will deliver about 0.8 x 0.8 = 64% of
its rated motor input power.

Jim