Basil's post on another thread reminded me of something that I thought about a long time ago but never got around to trying. An idea of a wind generator that could maybe work when we have the overcast days and no solar panels working.

I'm playing with a 12v alternator (as it already has regulator etc. built in) fitted with a normal small pulley............ mounted about halfway up on a pole. 

A fan......propeller...............of sorts mounted above it on the top of the pole.At the rear of the fan is a big pulley.

A belt is attached to the big pulley running down to the small pulley on the alternator. This should give it some speed.

Would it work??  Or would the belt cause too much friction and stop the blades??

Is it feasable??  Has anyone tried it before??  How big would the blades need to be??

It also has to made to be setup and fold up easily.

Some food for thought??



-- Edited by Disco Duck on Wednesday 25th of November 2009 11:52:43 AM

-- Edited by Disco Duck on Wednesday 25th of November 2009 12:11:42 PM

Hi Disco No they dont work too well as they need current to excite them, so if they are not charging they slowly flatten the battery. Most small wind driven generators use permanent magnet AC generators with rectifiers. You quite often see them on yachts & seem to work ok generaly set you back $600 up to what ever you want to pay.   Just noticed BobnBev hav a bit in the general forum under generators about this subject.

-- Edited by DeBe on Wednesday 25th of November 2009 02:27:53 PM

Thanks DeBe. I figured there was some reason why noone else had done it.

I just saw the same post from BobnBev. Might try something like that!

Just as a question...............what happens in the case of a normal car then. If the thing was unplugged when it isn't running would it still be a problem??

-- Edited by Disco Duck on Wednesday 25th of November 2009 03:08:09 PM

Hi disco hi debe, Yes this is my pet love low voltage living ect.. Used to work as a auto elect. many years ago .. And have made some funny looking wind gennies.. debe is right alt. dont make good wind gennies takes to much to turn them and they need volts to run the rotor..make it magnetic.. good on cars .. The old lucas gen. are good but need a little bit of speed.. I had a gyro at one stage and made a little genny for that out of a car 12 volt fan motor.. just enough to keep me in the air or the spark in the batt. The chineezzz are making some wind gennies now and seem to work find and dont cost the world.. Have a look in a Jaycar cataloge, like I said before I have a Xair 400 watt, that is real good and has put out 35 + amps in very high wind.. They can be ..are noisey little suckers but they do work at night .. only when the wind blows....smile just to get in first by what I read ....Thanks for reading my other posts....Bob

Hi Bob & Disco. I definitely wouldnt disconect an altenator from a vehicle battery with the engine running, if it was only idling probably wont hurt the Altenator but any spikes in voltage wont do engine computers any good. Daryl

A good comment De Be.Spot on..Ibbo.

Hey BobnBev.....................Thanks for your reply. What I meant about disconnecting the alternator was that DeBe mentioned that the alternator would flatten the battery when it wasn't running. So I asked (in my own way) if the alternator was disconnected from the battery when the alternator was not running, would that alleviate the problem? The alternator doesn't flatten the battery on a car when the motor is shut down. They can be shut down for long periods of time with no negative result. But no point in asking the question now as you have talked me out of the alternator project anyway :) I need to study up a bit more on the Auto electrics I think. Thanks all.

Hi disco, one can not know everything...smile.. some do... the only way your batt would go flat with the alt. conected is if the ign.light was in the line.. and left switched on..they are a 3pha.ac. thing and rect. that with diodes ..diodes wont let volt flow back against a ( npn or pnp 3 of each..which ever it is.. its been a while.. there are six diodes in a normal alt... unless one is stuffed and leaking.. thats what happens when you see your ing. light start to glow a little.. well one of them......... this could go on....the best wind gennie is a pro made thingy...Ive tried lots....Bob

Onya Bob........Thanks!! I hear you about the alternators....which is what I thought.......BUT i am no auto electrian so....I ask........!! I'll bet you have tried to make lots of the wind gennys..............doesn't matter if they don't all work, it is just good fun having a bash. You never know...........one day..........one will work and............Viola!! In the meantime..................I'll plug in to whatever is available for free or cheap or quiet !!

Free and cheap..............That about sums it up.Typical below decks answer.LOL.Cheers from the "Birdie".

Try pulling the panty hose over your head this time............ :)

Most of the truth around alternators has been in the replies but seems to have been set out in a hap hazzard manner.

The old generators were self starting as there was some residual magnetism in both the field and armature. However alternators are built with materials with little residual magnetism so they must be kicked into life. In your motor vehicle, when you switch the ignition on one of the things that is activated is the rotating field of the alternator.

The power to activate the field is supplied through the generator light on your instrument binnacle. This power is at a very low level but it is enough to kick the alternator into life. When the alternator starts to charge it supplies power to the field through the regulator. When this happens, the voltage at the alternator end of your dash light approaches the level at the battery end. That is why your dash light extinguishes - there is not enough voltage across it to make it glow. ( additional info - If there is a fault in the alternator, there may not be enough power generated to raise the voltage at the generator end of the light to extinguish the dash light. That is why it glows dimly or flickers when you have a slipping belt or blown diodes.)

An alternator without a battery load on it has an output that is far from a pure DC voltage. The alternator relies on the battery as a filter. That is why all learned authorities will tell you not to disconnect your battery - if you do you loose your filtering. In some cases not only will this output be so spiky that it will destroy the vehicles electrics, the alternator can destroy itself.

Disco Duck said "The alternator doesn't flatten the battery on a car when the motor is shut down. They can be shut down for long periods of time with no negative result." Yes it does if the ignition is switched on. If you had an alternator converted to a wind generator and have the kick start circuit connected at all times the alternator can discharge the batteries (in the simple case.) This would be equivalent to leaving your ignition switched on (a thing you normally don't do.)

Others mentioned disconnecting the alternator during low wind conditions. If you disconnect the kick start circuit, the alternator will cease to generate enough power to operate the regulator and thus power itself when the wind drops to a low enough force. When this happens there will be no drain on your battery, exactly the same as when you stop your motor in your tug. However you will have to kick start your system when the wind starts to blow again.

The big problem I see in using an alternator in a wind generator system is the power loss in the gearing. Whether you use gear wheels or belts, the gear ratio necessary to get enough speed in your alternator will be large. This will consume heaps of power from the fan driving the system.


















-- Edited by PeterD on Friday 27th of November 2009 08:45:50 PM

Onya PeterD Thank you for your reply and the replies of the the others. That idea is "OOT de WINDY MAN" !! Okay......so next question........instead of an alternator...................a generator?? There are still some floating around!

a battery is needed to "excite" the charge and to regulate the output to a certain extent (a bit like a couple of women I used to know) according to an old feller who lives in between port augusta and quorn, the output and therefore viability of an alternator in a wind turbine contraption is governed by the speed at which it can be turned the alternater needs to be turning at a rapid rate of knots to produce much at all, this old bloke has many contraptions which he uses to charge batterys and power his lifestyle, to get an alternator up to a decent charging speed takes a reasoanble ammount of gearing, gearing is friction and friction is thew winds worst enemy he has old car generators as well as other doohickeys dont know how they get on, all combined he can live reasonable off the grid, he has a wind powered washing machine, when the wind doesnt blow he reckons he just stays dirty, which I would believe