Getting the most out of a AA battery in 60 seconds before discharging

Discussion in 'The Projects Forum' started by eolithik, Feb 14, 2016.

  1. eolithik

    Thread Starter New Member

    Feb 14, 2016
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    I have 60 seconds to store the charge from a single AA battery before I discharge it to a DC motor. There is no restriction on the type or number of components in the circuit. I do, however, need two led's to be lit up at all times, during and after discharge.

    I was thinking of using a charge pump such as: [​IMG]
    with the R1 resistor as the DC motor, but i'm not sure where I would put the two led's.

    Is this my best option or should I use a boost converter instead?
     
  2. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Connect the battery directly to a bank of supercapacitors and let it charge them for 60 seconds. Energy transfer will be at its maximum through the whole cycle with the least bit of losses start to finish then put the set of capacitors in whatever arrangement of series or parallel you need to best match the motor's input requirements.

    As for the LEDs power them with a Joule thief circuit.
     
  3. crutschow

    Expert

    Mar 14, 2008
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    What voltage do you need for the motor?
    Are you concerned about efficiency?
     
  4. eolithik

    Thread Starter New Member

    Feb 14, 2016
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    I should also mention that I won't be able to touch the circuit during the entire duration except to flick some switches after the 60 seconds if needed. I was planning on choosing my motor to best fit my circuit? Should I do pick my motor first?
     
  5. crutschow

    Expert

    Mar 14, 2008
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    Yes, you should pick the motor first.
    How long do you need this motor to run and what load does it need to drive?
     
  6. eolithik

    Thread Starter New Member

    Feb 14, 2016
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    I was thinking of using this motor: https://www.pololu.com/product/61. I will only need to have it run for anywhere from 3-5 seconds with a load of 0.7 lbs
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    1uF caps will drive even the smallest motor for only a fraction of a second. You would need much higher capacitance.
     
  8. hp1729

    Well-Known Member

    Nov 23, 2015
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    Not much charge will be saved on the capacitors. A 1 F supercap only holds about 1 mAHr of charge, (From memory. I could be off on that. I figured it out many years ago but never saved the Excel file.)
     
  9. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Yes and it will also give you 360 ma for 10 seconds.
    Or since you have no restriction on the components you use you could just use a much larger super cap tha a 1F size.

    A ~350 F bank charged to 12 volts can start a vehicle easily enough despite having less total stored energy thanwhat a common C battery holds. :rolleyes:
     
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