wrote:
On Aug 2, 3:38 pm, Ernest Christley wrote:
What d'ya think, veedubber?

Unit is from a Harley-Davidson.
9.5 lbs installed (including all mounting hardware).
$288.17 (including tax)
38 Amps
No belts or pulleys.
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Seems like the way to go, doesn't it?

The first one I did like this was about 1970, using the dynamo from a
Honda 250cc motorcycle. At prop speeds it managed to produce enough
power for my ignition and an 8-track tape :-)

The later versions (as you are using) uses rare earth magnets... the
early jobbies used Alnico and weighed a ton. But the rare earth
magnets don't deal with heat very well and since the unit is only
about 50% effective, for every amps-worth of electrical output you've
got to deal with an amps-worth of heat. Usually, at prop speeds that
isn't a problem but spin it any faster and you can see some serious
side-effects due to overheating.

I'm not liking the sound of that. I'll be running it at 6000RPM, or so.
The intake air will be flowing over it, so that should do a lot to
keep it cool.


I mention this because of the 'submerged' location on your
installation. I think I can see a couple of oil pipes here that tells
me the excess heat is going to appear in your oil. You should know
that the rare-earth magnets tend to spall or flake when overheated.

The thin line on top pumps oil into the gearbox, and the 3/8" line along
the bottom allows it to flow back into the sump. They're not really
connected to the generator in any significant way.

We appear to be using the same stator & rotor but a different reg/rec
module. (I'm using the one sold by Great Plains) When properly set-up
I've got about 1mm of axial clearance between the poles of the stator
and the magnets. At prop speeds (ie, 2800 to 3000 rpm) it doesn't
take much skew to cause contact. Since my installations are not
submerged they're pretty easy to inspect and the bright line caused by
the momentary contact is always accompanied by a spew of abrasive
residue, ground off of the magnets.

I need to verify, but I'm fairly certain that the reg/rec I'm using is a
switching type. It turns off the line when the power isn't needed.
Saving the generator from producing heat in both the rotor/stator and
generator.

Since I run mine at prop-speeds the output is rather modest, only 8A.
to 10A, even through the momentary peak output is rated at something
like 40A. But with an electronic ignition system you only need about
5A to power the ignition system and maintain the charge on a small
battery. Truth is, I didn't want a system capable of producing the
maximum amperage since it would only get turned into heat at the
rectifier/regulator module.

I need to power ignition, injectors, pumps...and that's just to drive
the engine. There's radio's and lights that need a few electrons, too.

them.) If you'll look closely at the photos in my blog you can see
how I solved the problem :-)

And off I go to take a look.