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Forum Index : Windmills : Where do you rectify the current?

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heynow999
Newbie

Joined: 15/02/2009
Location: Canada
Posts: 13

Posted: 10:00am 11 May 2009

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I am new here so forgive me if this has been answered or is really obvious.

I am in the process of building my first f&p windmill. I was going to rewire it for 48v, but the inverter I have only takes 12v as an input so I think that limits me to a 12v mill? (and battery pack) I wanted 48v because of the smaller losses in the wire run. This got me thinking. If AC has less line losses, why don't I rectify the 3 phase AC at the charger rathter than up on the pole? Is that what is done? Does low voltage AC have the same losses as low voltage DC?

Thanks

PeterEdited by heynow999 2009-05-12

GWatPE

Senior Member

Joined: 01/09/2006
Location: Australia
Posts: 2127

Posted: 11:21am 11 May 2009

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For most applications, AC all the way to the battery bank is the way to go. DC if not insulated well can lead to electrolysis problems with wiring. The lowerst wiring loss occurs when the instantaneous current equals the average current. This occurs only with well filtered DC.

Gordon.

become more energy aware

oztules

Guru

Joined: 26/07/2007
Location: Australia
Posts: 1686

Posted: 12:34pm 11 May 2009

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Ac to the battery bank gives you more opportunity to play with things. You can use your dump load on isolated diodes, you can capacitor double, you can capacitor couple, short/oload the mill to stop without loading the rectifiers... and the list goes on.

At 12v, the caps may be of less use than higher voltage systems (although capacitor sizing may be the key here... and if you can cap couple (series), your transmission loss will be much less as voltage in the line will be much higher), but at least you are in a position to try them out if you wish to.... you can even drive different voltage battery banks concurrently with caps...plenty to play with.

Ac for me.... and don't underestimate the corrosion advantage.

...........oztules

Village idiot...or... just another hack out of his depth

heynow999
Newbie

Joined: 15/02/2009
Location: Canada
Posts: 13

Posted: 01:34am 12 May 2009

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OK, that makes sense.

So what I am thinking is a 48v mill that is rectified at the charge controller/battery bank. I will feed it into this charge controller

http://www.xantrex.com/web/id/72/p/252/pt/5/product.asp

A Xantrex c40.

Hopefully I can input 48v DC to charge a 12v battery bank. If not I may buy another inverter that can handle a 48 volt input. My ultimate goal is to have a battery bank in "the backshed" with a 110v AC (North America) circuit run up to the house. I will wire up a plug that can be used as back-up when the power goes out or a "green" plug if the mill produces good power.

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