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Electric generator

  1. Jun 5, 2010 #1
    im doing a simple home made project. wanting to know how i can use 2 electric motors to restore juice to the battery. i have 1 motor as my power source, with another as a generator, running on a pully system with a rubber band. I know i could use a gear system, but im lacking funds for gears that i can get at a hobby shop.

    How would i be able to use the 2nd motor as a generator to power the battery instead of the battery powering both electric motors?

    Im familiar with automechanics on a basic scale, but not towards it's electronic components, like the battery to the starter to the alternator back to the battery. Some how doing it on a small scale using 2 electric motors theres only a positive and a negetive wires from the motors. I dont know how or where to put my generator wires or meaning i dont know where they should go whether if i should have the negetive as a ground and have the positive wire to the battery as a positive return. If thats right then im going to need a little more motors or bigger pullies for the power motor and a small pully for the generator.

    Using the pully system like a bicycle theory, bigger sproket for the power source and a smaller sproket to transfer the power into the back wheel for motion. right now im using a 20 to 5 ratio on my pullies.
    Last edited: Jun 5, 2010
  2. jcsd
  3. Jun 5, 2010 #2


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    Staff: Mentor

    Welcome to PF.

    Reversing the polarity on the second motor will turn it into a generator. Also, it sounds like you're trying to build a perpetual motion machine. These are forbidden by the law of conservation of energy and PF guidlines.
  4. Jun 5, 2010 #3
    against the law? how so? and i guess self perpetual if you mean by self sufficient.

    i dont see how it is against the law. maybe if you can send me the link to show me because i wouldn't know where to find that law online.

    so on the second motor instead of the positive being positive, turn it into a negetive? how? and how would i hook that to the battery? to replinish juice the battery.
    if its against the law shouldn't people making home made generators be against the law to power their homes and cut out the electric companies from powering their homes.
  5. Jun 5, 2010 #4


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    Staff: Mentor

    I mean literally reverse the wires on the motor. And the law is the law of conservation of energy, aka, the first law of thermodyanamics: http://en.wikipedia.org/wiki/Laws_of_thermodynamics

    In other words, what you are trying to do isn't possible. You can try to recharge the battery with a generator while powering the motor, but you won't: the battery will discharge.
  6. Jun 5, 2010 #5
    it says nothing about it being "Against the law" and says nothing about being charged to a degree of something being self perpetual or something being self sufficient of it's own power. it only talks about the laws of what is listed below

    "The zeroth law of thermodynamics, which underlies the basic definition of temperature.
    The first law of thermodynamics, which mandates conservation of energy, and states in particular that the flow of heat is a form of energy transfer.

    The second law of thermodynamics, which states that the entropy of an isolated macroscopic system never decreases, or (equivalently) that perpetual motion machines are impossible.

    The third law of thermodynamics, which concerns the entropy of a perfect crystal at absolute zero temperature, and which implies that it is impossible to cool a system all the way to exactly absolute zero."

    You are right in words of the second so called law of it being impossible, if something is "impossible" nor physable, i dont see how it breaks any government law.
  7. Jun 5, 2010 #6
    whats the difference from changing the wires around on the motor than changing the positive to a negetive connection to the battery?
  8. Jun 5, 2010 #7
    "Some people like to say that "nothing is impossible." But this statement is a
    modern myth. One of the major functions of physics is to separate the possible
    from the impossible."

    http://www.phact.org/e/z/miltperp.htm [Broken]

    cant see how Perpetual Motion Machine is against any law or rules any where. As of PF is not specific on its rules of Perpetual Motion and it's discussions.

    Never say anything is impossible only because others can't do it.
    Last edited by a moderator: May 4, 2017
  9. Jun 5, 2010 #8


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    Hi Berry,

    You're on the quick path to getting banned unfortunately. What you are describing, as Russ has already pointed out, is a Perpetual Motion Machine.

    It will never work as it violates the conservation of energy. I can assure you that many people have tried, and ALL have failed and will continue to.

    Perhaps I can put it in terms that might make more sense. The Law of Conservation of Energy states that energy can neither be created nor destroyed, only transformed from one form to another. In the case of your battery --> motor --> generator --> battery system, the battery will always output more energy than the generator can input back to it. This is due to irreversibilities in the energy conversion process that start from the battery and goes through the motor and to the generator and back to the battery. In all real systems, as energy is transformed some of it is lost due to friction, copper losses, etc.

    Hence, the battery will eventual die.

    Hope this helps.

    Last edited by a moderator: May 4, 2017
  10. Jun 5, 2010 #9
    well capacitors store large amounts of power or energy, as how you have illastrated

    battery --> motor --> generator --> capacitor --> back to battery.

    A capacitor could restore the energy lost from the battery to the motor, because the generator is building the energy and storing energy for the battery. Like a audio sub system in a car, a capacitor gives the subs the energy they need for its performance, the alternator is building energy to the battery, battery to the capacitor, which is backwards if thought about. Thats why people have an extra battery for the audio system.

    i understand what you have mentioned with detail more than what russ explained on with his dead end replies.

    If the Law of Conservation of Energy violates my theory, then do tell about the car battery and alternator, when the car runs the alternator replenishes power back to the battery.

    Now i can't see how a theory or one's theory could be closed or banned when each little information can be gathered from different points to make an object work, as history is to be learned and not ignored.

    I bet in the past when Bill Gates was thinking about Microsoft people thought he was crazy till it actually came into production and now is the worlds finest computer. I bet all those people who thought he couldn't do it is now kissing their.... you know.

    If there is no information of those who tried, how do those trying improve the idea or theory? if all those who failed can be improved to make it right to work. it just takes the right info and testing to try. If you don't try nothing will be done.
    Last edited: Jun 5, 2010
  11. Jun 5, 2010 #10


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    Gold Member

    You can indeed use a battery driven motor to drive a generator which charges the battery.

    While it is running you should be able to feel the heat generated by both the motor and the generator, this heat is energy lost by your system. So while you are recharging the battery its total charge will drop until finally the system will slow down and come to a stop. It cannot continue to run due to the heat generated by the system.

    Why does a car battery/alternator system work, because it is being driven by a ICE which is converting liquid fuel to work. Part of that work is driving the alternator to charge the battery. A lot of the energy in the liquid fuel is lost through heat generated by the ICE so your system is not unique, virtually every device built by man does the same thing.
  12. Jun 5, 2010 #11


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    Staff: Mentor

    I never said anything about government law!
  13. Jun 6, 2010 #12
    You have to consider energy loss. In the simplest terms, every electrical component, including the wires connecting them, loses power to resistance. The motor and generator also lose energy to friction. (There is much more involved, but for now, electrical resistance is the biggest hill you have to climb.)
  14. Jun 6, 2010 #13
    One can look at it in another way.
    Assume the electric motor is 80% efficient.
    Assume the generator is also 80% efficient.

    With 100 watts from the battery driving the motor, the motors mechanical output would be as if only 80 watts were supplied to a 100% efficient motor. Understand?

    That mechanical output is connected to a generator. Effectively, only 80 watts are driving the generator from a 100 watt battery source. Make sense?

    Now the generator is 80% efficient. So, the generators output would be 60 watts.
    That's how much can be returned to a battery.
    So, that scenario uses 100 watts to generate 60 watts.
    See the problem?
  15. Jun 6, 2010 #14
    theres always going to be a loss of something in anything that is man made, even something that isnt man made, a bird will lose momentum when flying if it doesnt flap its wings.

    But im sure with the right gear ratios and a good capacitor there will be a good circulation of power going thru the system even with a loss of energy but that loss can be restored with like what i have mentioned with the right gear or pully ratio, im using a 20 to 5 pully ratio, if some dont know ratio, every 20 rotations on 1 pully is giving me 5 rotations on the other like a bicycle and its gears. With a electric motor and a generator im sure the power can be restored back to the battery efficient enough to continue for energy build up.

    Now see with ya'lls info that ya'll are giving me of ya'lls intell is only helping me make my idea and or system more efficient to become a better system to being able to work right. thats why i came on and signed up onto this site, because i knew there was or are good people to help me put my idea or system into a better perspective to be able to work right. One person couldn't of made a rocket work right with out others helping that one person to gather the right info or intell to build a rocket that would help the US beat the Russians to space and the moon. Thus there are more than one scientist on a project so one can help the other. I appreciate ya'lls input, so please keep it coming.
  16. Jun 6, 2010 #15
    No, that loss can not be restored without MORE energy applied to the system.
  17. Jun 6, 2010 #16
    Gears? What do you hope to achieve?

    A 10:1 gear ratio might increase your speed 10X, but, will reduce torque 10x.

    Conversely, a 10:1 gear can increase torque 10x, but reduce speed 10x.

    Gears are only applicable to circumstance(say, going fast or lifting heavy objects)
    They CAN NOT do both at the same time unless additional energy is applied.
  18. Jun 6, 2010 #17
    really dont need speed because the gears would pull the speed and the motors i believe create the torque (i think) dont have too much info on the gearing systems, thats why im doing a 20 to 5 to 5 ratio, the 20 is on my power motor and the 5's are on my generators, im in the process of testing my theory as we speak, as a battery would die in a meaning of 4 hrs or less this theory has been running for 2 days nows, yes the battery has decreased in power, but is keeping a small charge to its minimum power to keep the motor running for the generators to create energy for the battery. ive periodically been checking on my system and i have hooked up 2 LED lights on the generators to show that the generators are in working process and one LED on the battery to show the battery has power.
  19. Jun 6, 2010 #18
    In a machine like the one you're describing, part of the electrical potential energy of the battery is being converted to sound, heat, and other vibrational kinetic energy. No matter the quality of the generator or motor, you will always lose energy from your system.

    Even if you managed to remove all resistance, utilizing any energy would thus remove the same amount from the system. However, such a setup is impossible because the only true perpetual motion machine is the universe itself.

    Note that none of this is against court laws in any country, although it probably irritates patent workers with the numerous perpetual motion machine "ideas".
  20. Jun 6, 2010 #19
    OK, I'll keep it simple.

    The electricity produced by your generator is LESS than the electricity required to move the motor which moves the generator to charge the battery.

    Do you accept and understand this?
  21. Jun 6, 2010 #20
    yes i understand pallidin and vortico, then explain why my setup has lasted 2 days now with out hooking any other power source to my setup and it still running at a minimum speed, yes my power motor is warm and so is one of my generators the other isnt even close to being warm, from my generators my positive is hooked to the negetive on the battery and negetive from the generator is hooked to the positive to the battery, yes the battery gets warm, and yet its still running, if ya'll want to test this in your own homes feel free, because my setup has been running for 2 days straight. Using a lithium battery from a PS3 controller
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