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  • Pedal Powered Generator?

    Discussion in 'The main mechanical design forum' started by jawnn, Jan 26, 2012.

    1. cwarner7_11

      cwarner7_11 Well-Known Member

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      Motor Generator

      Your motor generator probably outputs voltage as a function of rpm. Which means, turn it slower to get lower rpm. You also need to determine the actual Wattage (or current) it is rated for. The flywheel might help you maintain constant rpm, but you are likely to be throwing away a lot of energy (relatively speaking) on keeping the flywheel turning...
       
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    3. jawnn

      jawnn Well-Known Member

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      Perpetual entropy machine

      The avatar picture shows how every push forward creates a equally redundant reaction.

       
    4. Dana

      Dana Well-Known Member

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      Well, now you have some numbers. You still need to choose how long you want to spend pedaling to recharge the batteries. Battery charge rates range from C/10 (1/10 the discharge rate) to C or even more. C/10 is a typical "trickle" (overnight) charge.

      You have 12V and a total of 24AH, which is 288 watt-hour. To charge them, you need to supply 288W for one hour, or 1W for 288 hours, or something in between. If your batteries can take a C/1 charge rate, a good athlete could charge them in one hour of pedaling. Note that these are approximate; you need more than 12V to charge a 12V battery and there are other losses involved in both the gearing as well as the generator, but it's well within the ballpark.

      But you also said something about using AA batteries? That's a lot less; they're typically around 2500 mAH (2.5AH) at 1.5V, i.e. 3.75WH per battery; as you can see that's a lot less.
       
    5. mhjones12

      mhjones12 Well-Known Member

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    6. jawnn

      jawnn Well-Known Member

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      what can actually be maintained:

      I set up a motor with a load and found that I can generate only 30 to 40 watts continuously.

      David Butcher says he can maintain only about 60 watts, and that's after he warms up. maybe a young healthy man can get up to 100 watts, but that's incredibly hard.
       

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