And folks, Jeremy says "Gee, that was fun".
Gust says, once again Jeremy is remarkable - his fun gives me a headache and
reminds me of the famous quote, "Any sufficiently advanced science is
indistinguishable from magic."
FWIW, I believe BMW hackers run an alternator out the side off the
crankshaft.
I'll have to try to find the picture.
Gust
-----Original Message-----
From: owner-virago@xxxxxxxxxxxx [mailto:owner-virago@xxxxxxxxxxxx] On Behalf
Of James J Schneider
Sent: Monday, January 17, 2005 10:12 AM
To: virago@xxxxxxxxxxxx
Subject: RE: how many amps does the Virago battery have???
"Will see if I still have picture - large pulley on hack wheel - alternator
hanging below with smaller pulley. May have has something to do with top
speed. That is an alternator rpm of 1100 at 20 or 30 mph would, perhaps
give
a come apart at the seams rpm at 80 mph. But, wadda I know???"
Just figure out the ratios. A standard alternator runs, just guessing
here, twice the engine RPM. So let's be conservative and figure a standard
GM alt is designed to turn 10,000 RPM plus, at an engine speed of 5,000
rpm. Let's also use Matt's info that it reaches full charge at 1100 engine
RPM. Pulley the thing on your hack for max rpm at 85 mph, which would be
like running an engine at 5,000 rpm. 5000/1100 = 4.55. 85/4.55 = 19 mph,
which would be the speed at which you reach full charge. It would charge a
fair bit at speeds somewhat lower as well. There may be a problem getting
the gearing set up right. The hack wheel turns much slower than 5000 rpm
at 85 mph - more like 1100 rpm or so. So you would need a drive pulley
mounted on the wheel that was 4.5 times the diameter of the drive pulley on
the engine, which is maybe 7"...7x4.5 = 31.5" - this is bigger than your
wheel, which might be a problem :-). OK, so you'd need a smaller alt
pulley. I don't know what sizes are available. You could also run a
jackshaft to increase the gear ratio twice, but that's getting a little
silly.
Gee, that was fun.
Jeremy
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