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Old 10-04-2015, 14:06   #1
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Small wind generator question

First off, let me say I'm not an engineer, so forgive my ignorance.

First my observation: Almost every day I sit in my boat at the marina and watch all the wind speed detectors (those little cup thingies) merrily and rapidly turning while at deck level the various wind generators on boats around me are either turning very slowly, or not at all.

My question that comes out of this observation is: Would it be possible to make a small trickle charger wind generator out of the wind speed detector device? If so, where would I find a small generator to use? Or would you lose too much through resistance because of the long wiring run from the mast top?

Any thoughts would be appreciated.

Gary
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Old 10-04-2015, 14:15   #2
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Re: Small wind generator question

You would need something else, but the answer is, yes you could do it, no you wouldn't get enough energy out it to be worthwhile, energy loss isn't the issue, energy generated is


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Old 10-04-2015, 14:38   #3
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Re: Small wind generator question

The cups spin because they have no resistance.
Once you try to generate power, you create resistance and it stops/slows the spinning.
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Old 10-04-2015, 14:45   #4
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Re: Small wind generator question

Why would you bother when solar is so cheap?

A small 10 or 20 watt solar panel plugged into boat and left in the cockpit when away would be a far better trickle charger setup.
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Old 11-04-2015, 10:35   #5
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Re: Small wind generator question

YES, you can build a very small wind generator, and its simple.
Simple does not mean easy tho.

Any permanent magnet DC motor can be used to generate electricity. A small one, like from a remote control car or toy could be used. In Canada we have a store called Princess Auto where these can be purchased pretty cheap.

Next, you need some fan blades. Plastic window blinds work well.

Now just some way to mount the blades, and connect to the motor. Maybe playdoh?

Any voltage over 13 will charge a 12volt battery. The current will be so low that you won't need a voltage regulator.

However, its a lot of work for a little power, when, like another poster said, you could just buy a small solar panel. Still, would be a cool project. Maybe get your kids to build one for science fair.
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Old 11-04-2015, 10:48   #6
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Re: Small wind generator question

Second the solar panel idea!!!!!!!!!!!!!!!!!!! So much easier and cheaper.
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Old 11-04-2015, 12:52   #7
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Re: Small wind generator question

Yes it's technically possible, but the amount of power is almost impossibly low.

The amount of power available is given by the formula...

P = 1/2 ρ A v3 (1)

where
P = power (W)
ρ = density of air (kg/m3)
A = area wind passing through perpendicular to the wind (m2)
v = wind velocity (m/s)

Just run the formula, but an anemometer has a radious of about six inches, at a wind speed of 30kn and assuming normal density (1.2kg/m^3) and efficiency of 20%.

Would put out .35w, and 14v that's old be .025amps.

If the wind drops to a more sedate 15kn .0442w or .0032amps

At a normal cut in speed of 5kn its .00164 or .00012 amps.


By comparison a .5w solar panel from RadioShack costs $5 and is 3"x2".

Not much return for the work.
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Old 11-04-2015, 13:33   #8
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Re: Small wind generator question

Or a simple resistance test. Go up the mast and poke your finger between the spokes and see how much force is applied to your finger. Then go to one of the neighbours wind gens and repeat the experiment. Let us know how it works out. Some typos expected...
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Old 11-04-2015, 16:51   #9
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Re: Small wind generator question

Your best bet is: get in touch with Missouri Wind and Solar. They should be able to guide you to get the best.

John L. Cwierz
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Old 11-04-2015, 22:57   #10
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Re: Small wind generator question

Here's a great site to check out they sell micro generators cheap affordable wind turbines made in the USA the wind blows and the sun shines though not always at the same time
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Old 13-04-2015, 06:47   #11
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Re: Small wind generator question

Quote:
Originally Posted by nimblemotors View Post
The cups spin because they have no resistance. Once you try to generate power, you create resistance and it stops/slows the spinning.
Exactly. First Law of Thermodynamics. Energy out cannot exceed energy in. The little wind cups are not trying to capture energy from the wind. They are just spinning freely (or almost so) and recording the speed at which they spin (which does require a little bit of energy, but not enough to matter). Try to capture a meaningful amount of energy from the wind and it requires a meaningful amount of wind energy to do it.

Conservation of energy: It's not just a good idea, it's the LAW!
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Old 13-04-2015, 07:54   #12
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Re: Small wind generator question

Good thought, but stick to a small solar panel.
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