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Forum Index : Windmills : charging AA batteries?

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mahela007

Newbie

Joined: 06/07/2008
Location: Sri Lanka
Posts: 29
Posted: 12:01pm 06 Jul 2008
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I want to charge batteries using my windmill. ( I havent built one yet.) Suppose it is hooked up to a motor that produces Direct current when the blades rotate. What kind of circuit should I use/ (I'm assuming I should use some kind of electronic component without just connecting the batteries to the motor...)
Another question I have is "what happens when the windmill slows down?" It wont always turn at the same speed so what effect will it have on the batteries that it has been charging?

how come its not very windy where i live???
 
KiwiJohn
Guru

Joined: 01/12/2005
Location: New Zealand
Posts: 691
Posted: 03:06am 07 Jul 2008
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Hi

The most basic electronic component you will require is a blocking diode so that the batteries do not try to run your mill backwards when there is no wind. If you use a motor that produce AC current, such as a stepper motor, you will need a rectifier bridge (which is really four diodes in one package) in which case you dont need the blocking diode too.

When the windmill slows down its voltage will fall below that of your batteries and charging will stop. Charging will start again when the windmill voltage gets above that of the batteries.

Although not essential you will probably like to have something to prevent overcharging the batteries and the easy way to do this is to 'dump' some of the windmill output to a dummy load. For a little mill that might be used to charge AA batteries you could use a zener diode and a resistance, you might not even need the resistance!
 
mahela007

Newbie

Joined: 06/07/2008
Location: Sri Lanka
Posts: 29
Posted: 03:29am 07 Jul 2008
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thanks.. by the way I would like to learn about electronic components like diodes. what is a good web site to do so/
how come its not very windy where i live???
 
Robb
Senior Member

Joined: 01/08/2007
Location: Australia
Posts: 221
Posted: 03:53am 07 Jul 2008
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This mill could be a good start for you.

Mini mill
 
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