Charge a battery with electromagnetic induction

Discussion in 'The Projects Forum' started by MikeTan, Aug 11, 2015.

  1. MikeTan

    Thread Starter New Member

    Aug 11, 2015
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    Hi everyone this is my first post, so be kind.
    My project should be really simple indeed: I would like to build a device that can charge a rechargable AAA battery using inductive energy.
    Regarding the inductive energy I already built a very-simple device made of one copper-made spiral and a powerful magnet (rare earth).
    Now the question is: how can I transform the alternate energy from the inductive device to charge the battery? I really don't care if the process is very long (the charging process i mean.
    One last question (just to know): how much does 1h of back and forth charge one AAA battery? (stupid quesion?)
    Sorry for bad english. And good afternoon (3 AM now)
    Thank you everyone
     
  2. #12

    Expert

    Nov 30, 2010
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    This has been done, and done well. You don't need a magnet, you need two similar coils placed rather close to each other, like one or two tenths of an inch (2mm-5mm). They might be flat spirals or they might be like a cup and its holder.

    You excite one coil with a suitable frequency sine wave and receive that energy as if with an air core transformer with the other coil. A diode or two and you have DC for the battery. A Ni-Cad battery is one of the most forgiving types for this. "How much and how fast" depends entirely on the design. You will have efficiency losses because of the air gap and you will have limitations on how much power you can force into the system without melting the driving coil. Several hours to full charge is a likely result.
     
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Usually many turns are used like below.
    To fully charge a battery would take a long time.
    [​IMG]
    Edit: when I saw back and forth This is what I thought of.
     
  4. #12

    Expert

    Nov 30, 2010
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    My nephew gave me something like that. It had a fake coil and a button cell battery. :D
    I suspect some of them are real, I just haven't met one yet.:(
    and I wouldn't try yanking it back and forth for hours to charge a battery!
    That kind of behavior is much better suited to building muscles than harvesting energy.
     
  5. MikeTan

    Thread Starter New Member

    Aug 11, 2015
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    The concept of the torch is what I had in mind, but the porposal of #12 suits better in my project.
    Can you please send me privately your solution explained in details? sorry but i am not very practical in this sort of things.
    Is it possible to use your idea to charge a battery with movement?
     
    Last edited: Aug 12, 2015
  6. #12

    Expert

    Nov 30, 2010
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    We don't do private consultations. This site intends to display information to all who seek.
    Look at the electric tooth brush. See that the base has a coil which envelops the bottom of the toothbrush. The bottom of the tooth brush also has a coil in it. You have to make a coil and frequency combination which will work as a driver. I think it can be done with the power line frequency, but that requires a LOT of fine wire in many turns of coil. I am not so good with coils that I intend to guess how to build it.
     
  7. MikeTan

    Thread Starter New Member

    Aug 11, 2015
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    The problem is that i need something that charges a battery using movement, like the torch.
     
  8. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    I have a real one, about 5-10 years old. Works ok, but LED tech was not then what it is now so it's a bit dim.

    ak
     
    #12 likes this.
  9. #12

    Expert

    Nov 30, 2010
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    Then start winding coils. More turns = more power transferred. Stronger magnet = more power transferred. Faster magnet movement = more power transferred.

    You can rectify the results into DC with one diode or 4 diodes. In this case, Shottky diodes are more efficient than the usual power rectifiers. What's stopping you?
     
  10. MikeTan

    Thread Starter New Member

    Aug 11, 2015
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    nothing is stopping me, i just didn't know how to do. thank you everyone anyway
     
  11. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    How many turns in the cooper spiral? What gague wire is it? Please post a photo.

    ak
     
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