Generating power from children - like the Matrix

[McDesign]

My 11-year-old son has been really intent upon trying to generate power from muscle energy, and we noodled this up this weekend.

We went to our local "Repairers of the Breech" store this AM, and found an old exercise bike for like $5.62 with tax; then to Wal-Mart for a ~$30.00, 400W inverter.

A drill motor wouldn't spin the little 24V / 250 Watt Chinese motor fast enough to make more than 10V - the inverter wouldn't cut on. Measuring and calculating, we figured the 20" exer-bike wheel with and inch-and-a-half diameter roller would give us enough rpm, so on went a urethane roller, and we just clamped the motor to the frame.

It worked! With no "pre-regulation" of the motor/generator output voltage, it varied directly with rpm. Son figured out quickly that the little exercise bike speedometer needed to stay between 14 and 19 mph, or the inverter would undervolt or overvolt.

First generation

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http://www.youtube.com/watch?v=d8iOQ9cbzh0

Then, with him pedaling smoothly, we plugged in a 100W bulb to the output of the inverter - it would glow for a bit, then the inverter would fault. We found that the exercise bike wheel was wompy (adjusting the spoke tension wouldn't true it), and the roller would slip under load at a low spot. So - then we became a 14th century lathe team - he'd pedal, and I'd run a lathe tool across the solid rubber wheel to true it up.

Tire lathe

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Tire lathe detail

Tire lathe detail.jpg (145.02 KiB) Viewed 1564 times

We welded an old door hinge on as a pivoting mount, then the motor/generator, with a spring to pull it against the tire. Tried it out, and now no skip - he could maintain speed and power output -

Generator detail

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http://www.youtube.com/watch?v=psw8GIL7qbQ

Then a long strip of 3/16" X 1" steel; inverter held on with J&B Weld -

Inverter mount 1

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Inverter mount 2

Inverter mount 2.jpg (94.82 KiB) Viewed 1531 times

Forrest

[McDesign]

The kids were excited; wanted to see what they could power - they found they could run the hand mixer -

http://www.youtube.com/watch?v=8DDfMqWsPnI

They convinced my wife they could mix long enough to make cornbread - so that's what we had for Sunday morning breakfast.

Next, they ground coffee, and my son found that with main strength and endurance, he could run the BLENDER at 125 Watts, and he made cucumber soup (Tadziki) for dinner.

It's interesting - there's really a huge drag when you turn the blender on - have to really push harder, but can't spin too fast, or the inverter input will over-volt. But, if you don't accelerate just as the load kicks in, it will under-volt. A buddy at work has promised to make me a DC regulator to go between the generator and the inverter that will make the pedal speed less critical.

Now they have a real sense of just how unapproachable the power requirements of the microwave and the oven are!

Forrest

[fechter]

Cool.

Now just add an old lead-acid 12v battery and you can store some energy. Half an hour of pedaling should let you run the microwave for about 3 minutes. You'd need a diode between the motor and the battery to prevent the battery from running the motor. With a battery in the circuit, you won't need a regulator. Once the speed gets up to battery voltage, the resistance will increase and prevent over volting the inverter.

[etard]

Sooo cool!! What a great father you are.

Kids have so much energy, why not harness it? I'm still trying to figure out how to harness the energy of my dogs.

[McDesign]

< Now just add an old lead-acid 12v battery and you can store some energy. >

Yep! I'll grab a couple diodes from the lab here today - I do have some batteries . . .

Forrest

[friedwires]

i like it forrest! now when there's a power outage,the kids wont complain about having nothing to do.

[jonathanm]

Love it - puts a whole new slant on the idea of empowering children!

[vanilla ice]

I could have a CANDY powered ebike.

[liveforphysics]

I love it! Your kids are getting a much better grasp of energy and power than most people will ever have.

If you had a LiPo pack hooked up (with a diode so it doesn't spin the motor when you stop pedaling), you could pedal for 10minutes, and microwave for 1 minute, and the kids could see how you can apply a trickle of energy over a long period to make a large amount of burst energy.

[Philistine]

What a cool dad.

It's funny you should raise this, because just yesterday I was saying to my wife that children are the hidden overlooked alternative energy source (I guess those in the times of the Industrial Revolution were onto that - and sadly most parts of the developing world today).

I can never get over how much energy comes out of my kids compared to the food and sleep that goes in. I have often thought if I could just harness it.....

Now you have me thinking, I reckon I could get off the grid when my youngest two are a bit older....

[jonescg]

Jon Thwaites here at UWA does these Fisher-Paykal washing machine exercise bikes. They put out three phases of AC power so he can tap into one of them to run blenders, drills and light bulbs. Great fun!

http://www.perthsunfair.com.au/toys/doc ... sAbout.pdf

[TylerDurden]

http://makerfaire.com/pub/e/6282

[liveforphysics]

What a cool dad.

It's funny you should raise this, because just yesterday I was saying to my wife that children are the hidden overlooked alternative energy source (I guess those in the times of the Industrial Revolution were onto that - and sadly most parts of the developing world today).

I can never get over how much energy comes out of my kids compared to the food and sleep that goes in. I have often thought if I could just harness it.....

Now you have me thinking, I reckon I could get off the grid when my youngest two are a bit older....

If you could get 200watts for 12hours apiece (which would mean they are outstanding specimens), you would be able to power your home comfortably, assuming you have gas heating and gas hot water heater. As a bonus, it would cost if your children's sanity and childhood! Woot!

They would need strong motivation to pedal though, maybe shackle their hands and feet to the pedals and bars, and have a system that lowers whatever they most fear down upon them should the cadence drop, and picks it back up again as the cadence picks up. Perhaps a wall of fire that lights and lowers towards them, or a lattice of hungry spiders/scorpions tethered to silk strings that lowers towards their faces, etc etc. Or maybe something simple, like a small oil fire burning under them, and the wheel they power has a little fan that is the only thing keeping the smoke and flame from burning their feet up.

(obviously all joking, as the fire options would cost a lot of fuel energy, and the bug options would be a lot of maintenance.)

[vanilla ice]

(obviously all joking, as the fire options would cost a lot of fuel energy, and the bug options would be a lot of maintenance.)

I was gonna say.

[McDesign]

I think maybe your exploding lithium battery YouTube vids could be properly motivating!

Forrest

[liveforphysics]

I think maybe your exploding lithium battery YouTube vids could be properly motivating!

Forrest

Yeah! They sit on a seat of LiPo batteries, and whenever they don't pedal, it closes a contactor that continues the over-charge process on the cell-seat they are perched upon.

Better pedal hard kids!

[fechter]

If you used a bank of coordinated nerve stimulators with electrodes in the right places, the stimulators could make the legs move involuntarily. Nerve stimulators don't take much power to work, so there would be a net gain. They could be asleep and still be pedaling. They might have some really sore muscles the next day, but I bet it would build them up better than a handful of steroids.

[McDesign]

Yep, it'd just be crazy not to do that. I'll start experimenting on the kids with those muscle stimulation things in the back of Pop Sci right away.

Forrest

[E-bike4life]

It's pretty cool to see this being applied. I have figured they should always use this idea in gyms and jails that have people that are wanting/made to ride an exercise bike, if even to only power the lights for a fraction of the day.

[fechter]

My nephew works for a company that actually makes such a thing. It is designed for people with spinal cord injuries that are paralyzed. They can acually build up enough muscle tone to propel themselves after a while.

[Jay64]

Nerve stimulators don't take much power to work, so there would be a net gain. They could be asleep and still be pedaling.

And you can wind up with the next Lance Armstrong. Make some money off those kids.

This setup is really cool. Great lesson for the kids. There are soooo many Americans that spend hours upon hours on treadmills and exercise bikes every week, if they all had a setup like this there would be quite a lot of power built up in the long run. Something like that could be a science fair winner.

[edcastrovalley]

Nice rig! I'm curious where you found those motors (generators)? I have 3 sons.

[McDesign]

I just used an un-modified 250-Watt 24V motor - most any scooter parts place has them for $12-$35 new. PM me for used ones I've got cheaper!

Forrest

[Jay64]

Hey Forest, you still got those motors?

[McDesign]

I do - what's up?

Forrest