magnet strength, homemade generator, and waterwheels

[Anthony Tomah]

Hi all,

I'm a newbie to the topic of home alternative energy but it is interesting
to me none-the-less. Bear with me here as I use ignorant language.

Question # 1 concerns magnets in the motor itself. Does the strength of the
magnet help determine the energy output? Some magnets certainly have
stronger pulling power than others. The magnets in the side of a chip clip
are not as strong as the magnets I pulled out of a hard drive recently.
Question # 2 concerns generator motor rpm. The motor on my large tablesaw
requires a certain amount of watts to turn at roughly 3600rpm. Would it
produce the same amount of energy if rotated in the opposite direction at
3600 rpm?
Question # 3 concerns waterwheels. Is there a calculator on the web or a
formula that will tell me how large a waterwheel sprocket has to be to
rotate a motor connected via chain or belt at, say, 3600 rpm? And, if there
are ways to do this and produce enough power, would it be feasible to design
a waterfall with a waterwheel to generate power, which in turn, powers the
pump to feed the water AND, and this is a big AND, produce excess power?

Thanks so much.

Tony

 

[Anthony Tomah]

Thank you everyone for giving me some excellent insight concerning my
questions.
To continue my question about magnet strength...perhaps I should be looking
instead at magnet size? I have a 3600 watt generator at home and have seen
the larger(more watts) ones in the stores. Is it such that the only
difference between the two generators is the size of the magnet or is it
also tied into RPM's or something else?
I'll explain my rationale concerning the gear ratio and/or wondering about
generating power with a waterfall to supply power to the pump.
Here is a link to a pump. http://www.powerpluspumps.com/perfpro.htm It
claims that on a 110 circuit, it consumes roughly 450 watts. Having no
knowledge of electricity beyond basic concepts, I figured, "Why can't I
generate maybe 1000 watts of power with a motor attached via chain or belt
to a large waterwheel gear and connect it to the small gear on the
motor(assuming I can even remotely get the gear ratio right), power the pump
at 450 watts and have a couple of hundred watts of excess? I'm not
suggesting this is even common-sensical thinking. I hope common sense does
not include waterwheels, gear ratios, etc. because if it did, I'm way
behind, but from my distant perspective I am wondering if it could be done.
I understand that it would not be perpetual as the friction, wear and tear
on the equipment, etc. comes at a cost, including down-time for repairs and
equipment swapouts. To make my idea even slightly more cloudy, I feel
confident there is an issue as well concerning the head height and flow of
the water which would impact the rpm of the waterwheel.
I think I did some decent(meaning somewhat accurate) calculations and it
appears that a roughly 1 inch diameter gear with 6 teeth would require a 24
foot diameter gear with 2592 teeth and would produce 2160 watts, assuming,
of course that my other numbers are even remotely applicable. These
assumptions are that 10 rpm of the waterwheel should equal 360 rpm of the
motor also assuming the motor requires 3600 rpm to produce 3600 watts. Lots
of assumptions here with no reasonable or unreasonable data to support it.
Anyway, it sounds to me that horsepower, plus a big honkin' magnet, plus
rpm, plus a little dash of confectioners sugar are factors that a 1 inch-6
tooth gear on a motor attached via chain to a 24 foot diameter gear on a
waterwheel equates to a do-not-try-this-at-home project. I know my math is
fuzzy here but am I in the ballpark?

Tony

 

[Gordon Richmond]

Thank you everyone for giving me some excellent insight concerning my

questions.
To continue my question about magnet strength...perhaps I should be looking
instead at magnet size? I have a 3600 watt generator at home and have seen
the larger(more watts) ones in the stores. Is it such that the only
difference between the two generators is the size of the magnet or is it
also tied into RPM's or something else?
I'll explain my rationale concerning the gear ratio and/or wondering about
generating power with a waterfall to supply power to the pump.
Here is a link to a pump. http://www.powerpluspumps.com/perfpro.htm It
claims that on a 110 circuit, it consumes roughly 450 watts. Having no
knowledge of electricity beyond basic concepts, I figured, "Why can't I
generate maybe 1000 watts of power with a motor attached via chain or belt
to a large waterwheel gear and connect it to the small gear on the
motor(assuming I can even remotely get the gear ratio right), power the pump
at 450 watts and have a couple of hundred watts of excess? I'm not
suggesting this is even common-sensical thinking. I hope common sense does
not include waterwheels, gear ratios, etc. because if it did, I'm way
behind, but from my distant perspective I am wondering if it could be done.
I understand that it would not be perpetual as the friction, wear and tear
on the equipment, etc. comes at a cost, including down-time for repairs and
equipment swapouts. To make my idea even slightly more cloudy, I feel
confident there is an issue as well concerning the head height and flow of
the water which would impact the rpm of the waterwheel.
I think I did some decent(meaning somewhat accurate) calculations and it
appears that a roughly 1 inch diameter gear with 6 teeth would require a 24
foot diameter gear with 2592 teeth and would produce 2160 watts, assuming,
of course that my other numbers are even remotely applicable. These
assumptions are that 10 rpm of the waterwheel should equal 360 rpm of the
motor also assuming the motor requires 3600 rpm to produce 3600 watts. Lots
of assumptions here with no reasonable or unreasonable data to support it.
Anyway, it sounds to me that horsepower, plus a big honkin' magnet, plus
rpm, plus a little dash of confectioners sugar are factors that a 1 inch-6
tooth gear on a motor attached via chain to a 24 foot diameter gear on a
waterwheel equates to a do-not-try-this-at-home project. I know my math is
fuzzy here but am I in the ballpark?

Tony

Anthony, try this link for information on using commonly-available AC motors as induction
generators: http://www.qsl.net/ns8o/Induction_Generator.html

Don't waste your time agonizing over choices of magnets etc., etc. The #1 thing that
governs how much electrical power you get out of a generator is how much mechanical
horsepower you can put into its shaft. Determine how much power is available from your
prime mover, and at what RPM, and then shop for a generator of similar capacity. If your
prime mover runs at only a few hundred RPM, you might be best off with a DC generator
charging a battery bank with an inverter to supply AC for domestic use. AC generators have
to run at a fixed speed, usually at least 1800 RPM for the smaller ones, in order to put
out 60 Hz power.

Big, simple, and durable should take precedence over small, light, and "cutting edge tech"
for a do-it-yourself project.

Gordon Richmond