Car alternator used with a water wheel or wind turbine

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britinbe's picture
britinbe
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Joined: Dec 28 2008
Posts: 381
Car alternator used with a water wheel or wind turbine

Given that alternators are plentiful, have a regulated output what are the practical considerations of using on of them as part of a water wheel or wind generator for eletricity generation?  My thoughts are to use a switch to charge up lead acid batteries and an invertor to give me my mains supply.  We have a small stream to the rear and a larger stream/small fast flowing river about 50 metres from our house.  I would gear up the water wheel to get a high enough rpm for the alternator.

Thoughts and considerations would be welcomed.

 

Tycer's picture
Tycer
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Joined: Apr 26 2009
Posts: 610
Re: Car alternator used with a water wheel or wind turbine

Yes it will work. They need to be spinning 3500 RPM and have a charged battery attached to work. Not really the best choice, but they will work.

 

Try http://www.utterpower.com/products/pmg/

robie robinson's picture
robie robinson
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Posts: 1182
Re: Car alternator used with a water wheel or wind turbine

3500 RPM's ? Just did the math on the single pole altenater used on my '49 Super A 12volt converted garden toy and it produces juice at half that. Not alot, but enough to keep'er goin'

 

robie

husband,father,farmer......

Ken C's picture
Ken C
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Posts: 753
Re: Car alternator used with a water wheel or wind turbine
Tycer wrote:

Yes it will work. They need to be spinning 3500 RPM and have a charged battery attached to work. Not really the best choice, but they will work.

 

Try http://www.utterpower.com/products/pmg/

3500 RPM seems awfully high. Most vehicles when idling will idle at less than 1000 RPM and the alternator will charge the battery.

I have been thinking of building a system myself with an extra 100 amp alternator that I have had sitting my garage for a while. I guess I need to just do it to see how it works.

Ken

edit: now that I think about it the pulley for the alternator is smaller than the drive pulley and therefore will turn faster. If the ratios of diameters are about 3 to 1 then maybe 3500 is not so far off. I guess I need to look into it.

Boomer41's picture
Boomer41
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Joined: Nov 30 2008
Posts: 135
Re: Car alternator used with a water wheel or wind turbine

A water wheel can certainly generate enough power to run an alternator. The main problem is the difference in speed between the two. As Tycer points out, an alternator must be driven at about 3600 rev/min to generate full output, which will be approximately 360 watts (12 volt DC x 30 amperes.) A water wheel will run very slowly- probably less than 60 rev/min, so a step up in speed to 3600 rev.min is required. This requires a gearbox, chain or belt drive with a 3600/60 = 60:1 ratio.

Since step-up gearboxes tend to be very inefficent, and very large diameter v-belt pulleys are hard to find, I would recommend a chain drive. This implies a 60:1 ratio of sprocket diameters. The smallest practical sprocket diameter is about 1", so a single stage drive would require a 5 ft diameter sprocket on the water wheel.

Easier to achieve with off the shelf components, would be a 3 stage system with two intermediate speed layshafts. That is to say the water wheel drives a first layshaft at, say 4:1 step up. The first layshaft then drives a second layshaft with another 4:1 step-up. The second layshaft drives the alternator via a final 4:1 step up to achieve a total 4 x 4 x 4 = 64:1 speed increase. (A bit more than needed but keeps the math simple)

Bicycle chainwheel / rear sprocket combinations are readily available with 4:1 ratios. You need to do more research to see if bicycle chain will stand up to the speed at the alternator end and the tension at the waterwheel, both of which exceed what is normally seen on a bike.

As you can see this is not trivial. By the time you are through paying a machine shop to build a suitable chain assembly, you might be better off to buy something already designed and built by these guys: http://www.utilityfree.com/hydro/

 

 

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