Posted: 03:52am 30 Jan 2006

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Hi all..

I notice almost everyone is using the F&P stators for their windmills and must have run these up on lathes etc to work out optimum speeds..

can someone tell me (cause i dont have a lathe) what the rpm ranges are for a single motor to be able to produce 14v to charge a battery bank ? also how many amps / watts does this make at this speed ? (dont give me wind speed, just RPM please as that i can calculate with)..

thank you

John 

Posted: 04:31am 30 Jan 2006

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Hi John.

The F&P makes about 1 watt per revolution. We aim for the 300 - 500 RPM range, or 300 to 500 watts, as its the best balance between blade diameter, TSR, all that stuff.

I dont have the volts per RPM figures, it depends on how you have wired it up. But one of the guys here will be able to help.

Glenn

Posted: 02:08am 31 Jan 2006

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Hi John.

Yes thats right, a F&P can make 1000 watts at 1000rpm. Buts thats about the limit I think, any fast only gives small gains.

I know what your thinking, make a set of blades for 1000RPM. But it wont work. Its a balance between blade size, RPM and watts. This is why we usually aim for the 300-500 RPM/Watt range using a prop diameter of about 2 meters. To get more watts you need a bigger blade, but a bigger blade is slower and wont spin the F&P at the higher RPM needed to get the extra watts.

There are ways around the problem, like replacing the magnets with neo's will almost double the power, or use a big blade and a gear box to step up the F&P RPM.

Glenn 

Posted: 04:29am 31 Jan 2006

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Also i think the max rpm for the F&P is around 1000rpm, or a bit more. Its on the Ecoinn website