# Want to covnert electric lawn mower into a AC generator

Discussion in 'General Electronics Chat' started by ElectromagnetNewbee, Sep 27, 2014.

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1. ### ElectromagnetNewbee Thread Starter Member

Jul 13, 2014
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I want to use my old electric lawn mower motor and convert it into a AC generator.

From my understanding. I should be able to take that electric motor that has hard magnets in it and spin it and it should give me ac electricity correct?

I think it was an 36 amp motor. does anyone have an estimate on what frequency/hertz it would produce? and approximetly how many volts and amps?

2. ### LDC3 Active Member

Apr 27, 2013
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It's very likely that you will get current when you spin the motor, but I think it will give you a varying DC current, not AC; it will always be positive, but might be zero periodically.

The frequency of the peaks will depend on how the motor was wound. As to the output, if you can spin it as fast as when it was powered by a battery, you should get almost 36 amps and the voltage of the battery.

Of course I could be wrong and you get nothing.

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3. ### Thecomedian New Member

Oct 12, 2013
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Well, if you had a circular coil surrounding the motor and taps in 4 equidistant places, you would get positive voltage when the magnets are moving towards each tap, while getting negative voltage as they move away from the other taps, right?

4. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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We need more info on the 'motor' you plan to generate with. What voltage and freq did it require to operate as a motor? What information is printed on the motor?

generally speaking a motor will give you approx. same output as a generator as it required to run as a motor, when turned at the same RPM. (induction motors are a whole different beast)

The speed at which your lawn mower turns the shaft will determine your freq., or your Hertz output. We can tell you it is 60 Hz, but if your lawn mower doesn't spin it at a proper speed then you will NOT get 60 Hz.
The volts and amps are also closely related to the speed at which your lawn mower can turn the motor shaft. The voltage regulation is going to be related to the RPM's as well. How well can the lawn mower maintain a steady rate of speed , etc.
If your motor needed 220 volts to operate then it will be a 220 volt generator, or if it required 110 volts then that will be the output, as long as proper RPM's are maintained.

The answers to your questions all depend on that motor you intend to use as the generator.

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Jul 18, 2013
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There are three types of motors used in power tools, Universal AC/DC series motor, DC brushed, AC BLDC.
The 1st is out, the second will generate DC, the third AC sinusoidal voltage, frequency dependent on # of poles and RPM.
An induction motor is also out as it will not generate.
Max.

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6. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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an induction motor will generate, but not in the way the OP wishes to build a generator. it must be run as a motor and then be driven faster than it is running(simple version)

7. ### shteii01 AAC Fanatic!

Feb 19, 2010
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Can you show a block diagram that shows how electricity moves from wall outlet to the motor?

8. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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i am not sure if your question is to me, but you can find answers about induction generators at wikipedia. and yes they can back feed directly into the power grid when started from a standard wall outlet as a motor

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Jul 18, 2013
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Presuming it is disconnected as a motor at some point, where/how is the field generated?
I don't see it being very efficient?
Max.

10. ### Kermit2 AAC Fanatic!

Feb 5, 2010
3,854
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im not good with this phone, so i would kindly suggest you go to the wikipedia site snd do a few seconds of research. they are quite efficient in large sizes. some wind farms use them because they feed the grid directly without conversion stages.

Jul 18, 2013
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All the ones I could find mention adding P.M.'s to the rotor?
Max.

12. ### alfacliff Well-Known Member

Dec 13, 2013
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a friend of mine sells wind generator kits, using 3 phase induction motors. they get their excitation vrom the ac line, and have no permanant magnets on them anywhere. a lot of the small generators sold in stores use induction motors too, with fairly large value caps to help the residual magnetism build up current to generate as stand alone generators.

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13. ### ElectromagnetNewbee Thread Starter Member

Jul 13, 2014
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Wow, great info for me. thank you my friend

14. ### ElectromagnetNewbee Thread Starter Member

Jul 13, 2014
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wow. this is honestly such really cool information for me. I love how electricity works, its so much more complex than I had previously thought. Im just a hobbyist now basically, my gf makes bank in nyc so im lucky enough to not have to work.

15. ### ElectromagnetNewbee Thread Starter Member

Jul 13, 2014
69
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[QUOTE="alfacliff, post: 767590, member: 227055"with fairly large value caps to help the residual magnetism build up current to generate as stand alone generators.[/QUOTE]
nice. so i will add a large capacitor into the circuit. someone send me a link to a large value cap on amazon so i get the size right.

16. ### ElectromagnetNewbee Thread Starter Member

Jul 13, 2014
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I only have the motor and the magnets, I lost the brackets that hold it all in place. where can i get on amazon a mounting system brackets for this thing?

17. ### ElectromagnetNewbee Thread Starter Member

Jul 13, 2014
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nice. does that give me a discount on electricity for my apartment then? ha

Jul 18, 2013
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What is the Nature of the motor AC? DC?

I am not sure I would bother when there is plenty of P.M. motors around, I know the Fisher-Paykel W.M. motor is popular for wind generators.
Max..

Jul 13, 2014
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