Discuss Alternator use for micro hydro in the Auto Electrician Forum area at ElectriciansForums.net

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Danran

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Hey. I'm setting up a micro hydro system and thought some guidance would be nice to avoid unnecessary experimentation.
This is my first version but the idea is to use the water to push a pelton wheel to turn an alternator. However with this first test i am only reading about 2 volts off the alternator. Is it just not spinning fast enough?
The second part of this set up if i can get the 12 or more volts would be to hook that directly to an inverter to power my house(mostly lights and a few other small things). Would this work?
I will probably invest in a battery bank in the future but would like to get this going cheaply to start.
Thanks for any help.
 

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As above, you would need several thousand RPM for a typical automotive alternator. Or some gearing.
 
It looks like you have not connected up the excitation (field) circuit of the alternator, in which case it usually won't work at all, or would require mega-high-speed rotation to start up. The voltage you are seeing is just the result of some residual magnetism in the rotor.

Different alternators and vehicles use different circuit configurations for the excitation feed and warning-light (which are often inter-related) so you will need to find out the connections required for your specific model. In some setups the vehicle battery positive supplies current to the field circuit via the ignition switch all the time; in another it only supplies the field via the warning light and only until the alternator has fired up, after which the alternator runs independently although might need a permanent battery feed to the regulator sense input.

In any case, many alternator regulators require a battery connected to the output to function properly, or the lack of a battery can cause the rectifier bridge to self-destruct if the load current is suddenly switched off. The battery doesn't need to be very large, but trying to avoid using one at all is likely to add all sorts of problems and complications.

Re. speed comments, my impression is that it may be spinning fast enough especially with what seems to be a high belt drive ratio, but the rotation is strobing with the camera frame rate and sometimes the shaft appears to be rotating slowly forwards and sometimes backwards. Whether the wheel will deliver enough torque to generate useful output when the load comes on, is another matter.
 
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It looks like you have not connected up the excitation (field) circuit of the alternator, in which case it usually won't work at all, or would require mega-high-speed rotation to start up. The voltage you are seeing is just the result of some residual magnetism in the rotor.

Different alternators and vehicles use different circuit configurations for the excitation feed and warning-light (which are often inter-related) so you will need to find out the connections required for your specific model. In some setups the vehicle battery positive supplies current to the field circuit via the ignition switch all the time; in another it only supplies the field via the warning light and only until the alternator has fired up, after which the alternator runs independently although might need a permanent battery feed to the regulator sense input.

In any case, many alternator regulators require a battery connected to the output to function properly, or the lack of a battery can cause the rectifier bridge to self-destruct if the load current is suddenly switched off. The battery doesn't need to be very large, but trying to avoid using one at all is likely to add all sorts of problems and complications.



Re. speed comments, my impression is that it may be spinning fast enough especially with what seems to be a high belt drive ratio, but the rotation is strobing with the camera frame rate and sometimes the shaft appears to be rotating slowly forwards and sometimes backwards. Whether the wheel will deliver enough torque to generate useful output when the load comes on, is another matter.

Ok I'll probably just hook it up to a spare car battery. This is the same alternator that is in my truck so i have a reference for wiring. But if i were to use another alternator can you think of a specific one that may be best for this purpose? Maybe one from a specific model of car or truck that i could find at the pick and pull?

Yeah i think it is spinning fast enough as well was just thinking maybe it is just below the threshold to work. But I'll try with battery first.

Thanks for the reply I'm excited to get this going! Also working on moving up my water intake to get even more water pressure so hopefully that will help once i start putting a load on it.
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Follow the wiring diagram to find which wires are feed(s) that need to be hot for the alternator to work, and which are for other functions like the warning light and temperature sensor if fitted. If you can post a link so much the better.

Amongst truck alternators, there probably isn't that much to choose between models. Any good quality unit that is rated high enough to absorb all the mechanical power your wheel can produce, is going to deliver similar results, as they are all built to relatively similar specs for any given output. Test the performance of your wheel before investing in a better alternator (or trading up to a more efficient type of generator). You can tune the efficiency of a generating system by carefully matching the machine and the drive ratio to the motive power source, but unless you have the performance curves for alternator and wheel, you don't have enough information to do that.

You might however be able to find someone who has done practical tests with a similar setup and has collected some data.
 
I saw a guy on YouTube using a washing machine to make power for his off grid home, have you tried that?

Yeah i saw that one too but that requires doing something to the motor and im not super experienced with this stuff as you may be able to tell.
I may try something like that in the future though we'll see how alpha version works :)
 
A lot of small hydro schemes use over run motors but you need power to it. I don’t think a washing machine motor would be a good choice as they have several different winding.
 
Hey. I'm setting up a micro hydro system and thought some guidance would be nice to avoid unnecessary experimentation.
This is my first version but the idea is to use the water to push a pelton wheel to turn an alternator. However with this first test i am only reading about 2 volts off the alternator. Is it just not spinning fast enough?
The second part of this set up if i can get the 12 or more volts would be to hook that directly to an inverter to power my house(mostly lights and a few other small things). Would this work?
I will probably invest in a battery bank in the future but would like to get this going cheaply to start.
Thanks for any help.
I remember reading about a man in Alaska that made an off grid hydroelectric system. A couple of interesting points about his system is that he used an alternator from a forklift. Also to cut cost of his system he did not have a battery bank (his flow remained the same year around and he placed his pipes underground as not to freeze). The excess electricty went to a water resevoir. I've searched for the article and if I find it I'll post it here.
 

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