Re: 120A alternator: hp drain?

[T Berk <tberk@mindspring.com>]

Scott Williams wrote:
> 
> Guys, I'm interested in purchasing a 120A alternator for the Warpiggy.
> You know -mega watt rally driving lights and stuff. Anyway, will this
> heavier duty unit sap more horsepower than the 90A unit that I've got in
> there right now -sometimes/ always? ... <snip>

Here is my understanding of the HP loss and energy generated by an Alt.

(Quick answer up front: No great loss of HP)

The Alt produces energy from mechanical motion which it converts through
the interaction of the electromagnet's' field and the windings passing
through said field. <pant. pant>

There is some is some drag from friction (should be the same for both)
There is some loss from air resistance (little fan on Alt, same)
There must be a larger electrical field the windings have to plunge
through, here is the only place I foresee a difference in load. Could it
rob say as much as 5 HP? I don't think so. Now an A/C unit- that has to
do some real work, but a larger Alt?

One of the main reasons a given alt puts out a given amount of Amps is
the voltage regulator, design a bigger one and you can fry the
lowest-cost-possible-in-large-batches-for-a-mass-market type Alts'
components commonly found in a car.

I think the only prohibiting factor is the cost of the larger unit.

Now, some one who actually _has_ one of these might want to wipe me out
on this.  

TBerk

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