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Forum Index : Windmills : 12 or 24 Volt car alternator mill?
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VK6MRG Guru  Joined: 08/06/2011 Location: AustraliaPosts: 347 |
Hello, I'm new to the forum and have a quick question about automotive alternators being used for a wind generator. Can it be done? I was thinking of adapting an alternator to run off the side of a standard wind mill (Southern Cross, water type). Some gearing issues maybe a problem but no too much trouble to overcome. I was thinking of adding the output of the alternator to a DC bus to charge a battery bank and running an inverter (via a charge/load controller). Regards, Matthew Its easier to ask forgiveness than to seek permission! ............VK6MRG.............VK3MGR............ |
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vawtwindy Newbie  Joined: 23/10/2010 Location: IndiaPosts: 31 |
You need to have high RPM for automotive alternators, will you be able to gear it ? |
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| VK6MRG Guru Joined: 08/06/2011 Location: AustraliaPosts: 347 |
I thought i'd just use three or four stage gearing to increase the RPM up to about 1:40. I was looking at a speed sensor so a solid state relay will bring in the power to the rotor, this way when the RPM's are low the alternator will unload so the wind mill doesent stall. Its easier to ask forgiveness than to seek permission! ............VK6MRG.............VK3MGR............ |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
VK6MRG Hmmm . . . right off the top, I'd say this is kind of a bad idea. The Southern Cross windmill uses a blade, which boils down to a compression wheel. Its speed is limited by the fact that each blade follows in the wind shadow of the blade ahead of it. Torque it has, speed it doesn't. If you were to gear it up enough to run an antomobile alternator, you'd have to get the alternator's shaft speed up to nearly 10,000 rpm for it to work as it was designed to do in the vehicle. That's unlikely. I think if it were I, I'd plug in the data from your windmill (diameter, number of blades, wind speed, etc.) into Alton's Calculator to see just what kind of power is available. There's no sense spending lots of time trying to tread water while holding a millstone, right? Use the link I've provided and see what you've got BEFORE you start building. You'll notice that 99% of all the other wind-electric builds use a turbine of not more than a maximum of about 5 blades. There's a good reason for that. If you go through all my builds, you'll see I'm the guy that builds "toys" here. I like little stuff, but the principles are the same, big or small. I'm currently working on a little mill, which is intended to provide a "topping charge" to a 12-volt battery. If you want 24 volts, just double the windings (more or less) on the stator and provide enough wind power to drive it and there you have it. You'll soon find that just because you have a dandy alternator, that doesn't mean your wind situation or windmill it self will actually propel the thing. There's a lot more to this hobby than meets the eye. Just look around at the scads of things folks here have tried; only very few are what anyone would term "successful". For me, it's just a hobby, so failure means nothing. Hope this bit of advice helps you on your way. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Matthew, welcome to the funny farm ... Matt Lyons ,who lives in melbourne, made a 24v version by fitting Neo magnets where the field windings were . You could see his work by searching on this forum (m Lyons) ,,I think . It was a long time back ,but he showed me his work when he visited my place .. I have a 24v truck alt ready for vonversion , pic's are somewhere in my irc pic album and also under my name (brucedownunder) on this forum. Matt used to set his up on the beach when he went camping.. Bruce. Bushboy |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Yeah I have to agree, the farm windmill turbine is designed for torque, not power or speed. They are only about 15% efficient, where a typical 3 blade electricity generating turbine is 30 to 40% efficient. 45% is the Betz limit, you wont get any more than that. So even if you geared it up, your still going to be way down on power compared to a 3 blade turbine. This is Mats page http://www.thebackshed.com/Windmill/articles/MattLyons.asp , he fitted neo magnets to a 24volt alternator with OK results. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| VK6MRG Guru Joined: 08/06/2011 Location: AustraliaPosts: 347 |
From what I know about Power and Toque, the wind mill should have more than enough toque for the job, Only a small output alternator (35A), and after I alter the winding connections it will only be about 15A. I'll have a read through Matt Lyons thread and see what the go is. Its easier to ask forgiveness than to seek permission! ............VK6MRG.............VK3MGR............ |
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| VK6MRG Guru Joined: 08/06/2011 Location: AustraliaPosts: 347 |
Hi Glenn, that last post was a spammer I take it. Do the spammers realy think we are that dumb to get tricked into clicking on one of the links that they have in their fake post. Its easier to ask forgiveness than to seek permission! ............VK6MRG.............VK3MGR............ |
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