Sunday, October 16, 2011

Re: [Electric Boats] Well, I am pleased to meet you, won't you guess my name.

 

Okay from the sounds of things you like to tinker in your shop....   In your post you imply how easy it is to turn an alternator over by hand. SO you may be getting what a few hundred RPM, this is still below the cut-in RPM needed to start making power.  Did you have the Rotor excited while doing this?

By hand you can spin a crank at about 120 RPM, cut in RPM on most auto alternators is around 2000 to 2500 RPM so to get it into a reasonable charge range you will need around 3600 RPM. SO make a set-up that has a 30 to 1 step up ratio and see how easy you can turn that crank with the rotor excited.

Just so you know when I was in the US Army I had the fun of using one of the 24 volt hand crank field genorators to charge our field radios. I think they were about 200 watts.

--- On Sun, 10/16/11, Lochadio Who <lochadio@yahoo.com> wrote:

Architects live in a fantasy world.
Engineers live in a perfect world.
and it's up to the field guys to drag them (kicking and screaming) into the real world.

I apologize for correcting our esteemed member, but anyone with any doubts should try spinning an auto alternator by hand.
I'll post a video ASAP

...Before you ask, no, I don't know how many watts it puts out.

Regards

Mark

From: Ben Okopnik <ben@linuxgazette.net>
To: electricboats@yahoogroups.com
Sent: Sunday, October 16, 2011 12:45 PM
Subject: Re: [Electric Boats] Well, I am pleased to meet you, won't you guess my name.

 
On Sun, Oct 16, 2011 at 07:59:14AM -0700, Femm wrote:
>
> 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.

Nice. I'd never heard of it, but it makes a lot of sense. So, 150A @ 15V
is 2250W and takes 5-5.5HP on a belt system; pretty much dead on with
Nigel's estimate.

--
Ben Okopnik
-=-=-=-=-=-




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