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Ask MAKE: Kid-powered battery charger

Ask MAKE: Kid-powered battery charger

Ask MAKE is a weekly column where we answer reader questions, like yours. Write them in to mattm@makezine.comor drop us a line on Twitter. We can’t wait to tackle your conundrums!


Phil writes in with an interesting question:

When I found out about this neat Ubuntu tablet that is powered by AA batteries, I started wondering if it’s possible to recharge those batteries using the musclepower of kids.

Sure, it’s easy enough for adult muscle power to generate some electricity, but could there be some ways for kids’ musclepower to be harnessed (gently) to recharge AA batteries?

What kind of not-very-tiring machines could be devised that could store mechanical energy in such a way that the energy could later be released more quickly to recharge AA batteries via a cordless power drill running in reverse?

Of all the possible machines that could be set up (pulley systems, water pumps, hydraulic lifts), which would be the simplest, least costly and least dangerous to set up? Are there any kinds of contraptions that could be created so that even a five year old could be involved in creating electricity to recharge AA batteries?

While this would be a potentially fun tool for families to use here in the United States, this could be a vital energy production/computing/education tool for families where there is no existing electrical infrastructure.

The idea of storing up a bunch of mechanical energy in order to power a high-torque generator is a good start, but I don’t think it is the right way to go. Instead, it would probably be better to skip the cordless drill, and use something designed to be a crank generator. Most rechargeable batteries can be trickle charged, or charged slowly, so it is probably better to design a hand crank that is easy to turn, and just puts out lower current. Of course, the the trade-off is that it will take longer to charge the batteries. I would start with this design for an ipod charger.

Another alternative might be to make a kid-sized pedal-powered generator, and use that to charge the batteries. David Butcher made one that looks really nice, and sells plans from his website.

Anyone have other ideas about how to harness kid power to charge batteries? How about a giant hamster wheel?

20 thoughts on “Ask MAKE: Kid-powered battery charger

  1. Mystech says:

    I’ve always believed that “children are the future”. Now I see that applies to energy shortages as well. :-)

  2. Zach says:

    I’d suggest some sort of panel or other device which turns boring old cranking into some kind of game. Maybe something with a lot of different ways to generate power, or a game that relies on turning cranks, pulling ropes, pumping levers… maybe a marble run, as well as a battery charger: turn the crank and watch this set of parts operate (while winding a spring or raising weights or otherwise storing power), then stop, push a button or flip a lever/switch and watch this other set of parts go, both sets of which power the charging subsystem.

    1. Matt Mets says:

      I like it! That’s probably a good strategy for adults, too.

  3. oljanx says:

    When my children play in the yard, I keep them tethered to a generator. When they run about the tether drives a small turbine. The turbine is used to charge batteries which are then used to replace the dead batteries in their toys. Ok I made that up, but it’s starting to sound like a good idea.

    1. Matt Mets says:

      Yes, as long as someone else feeds them!

  4. says:
  5. Anonymous says:

    How about adapting something like the merry-go-round water pumps, attaching a generator instead of a pump.

  6. Anonymous says:

    How about a swingset that generates electricity?

  7. Stephen says:

    It’s very patronising to apparently decide that kids are useless and need specially designed equipment to even work. You don’t give children special, “gentle” bikes to ride on, you give them smaller bikes that are sized for their frame. The work they can do with them is just as good (better if you’re fat) as you.

    1. Matt Mets says:

      Right, you just have to scale things so that they are appropriate for their size. I think this is what we are talking about?

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