--- On Sun, 10/16/11, Ben Okopnik <ben@linuxgazette.net> wrote:
From: Ben Okopnik <ben@linuxgazette.net>
Subject: Re: [Electric Boats] Well, I am pleased to meet you, won't you guess my name.
To: "electricboats@yahoogroups.com" <electricboats@yahoogroups.com>
Date: Sunday, October 16, 2011, 6:57 AM
On Sat, Oct 15, 2011 at 07:21:34PM -0700, Lochadio Who wrote:
>
> You could easily run four 100 amp automobile alternators off a 4 horse lawn
> mower engine.
That's a little optimistic. :) Since 100A * 15V = 1500W, (a.k.a. 2HP),
two of these at full load would max out a 4HP engine, which would have
to be carefully tuned and run at a fixed speed to put out that full 4HP
(and it would have a rather short life, running at that max output all
the time; gas engines aren't very good at that kind of thing.) Add in
the friction losses, and even two 100A alternators is a bit much.
As I recall, Nigel Calder estimates that a 150A alternator at a 5HP load
on the engine. That may be a bit too generous, but it's in the general
area. On the other hand, a civil engineer friend of mine designed a
block of apartment houses for a Third World country which provided all
the needed electricity, heat, and hot water they needed off a single VW
car engine (30HP or so.) Obviously, they have to be rather conservative
in how they use and allocate the output, but I found that pretty
impressive.
--
Ben Okopnik
-=-=-=-=-=-
The simple rule is you can pull 450 to 500 watts per horsepower direct drive and 400 to 450 belt drive per horsepower on small power sources. Like single cylinder engines.
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