Please note this isnt a freewheeling perpetual energy device.

I'm an artist planning on making a public art sculpture that generates electricity using human powered energy input. By means of a crank to turn a flywheel connected to a DC motor. Ideally enough electricity to power about 12w LEDs and hopefully generate enough power to charge a cell phone. My sculpture also has a solar panel that will also charge a battery for extra power. Both units will connected to the battery.

First off is this remotely possible and does the flywheel help. I am under the assumption that the flywheel will store momentum and continue to aid in the generating of electricity. Is this correct. I know this will also depend on the DC motor used......I can purchase any size.

Thank you for your help.

 

Please note this isnt a freewheeling perpetual energy device.

I'm an artist planning on making a public art sculpture that generates electricity using human powered energy input. By means of a crank to turn a flywheel connected to a DC motor. Ideally enough electricity to power about 12w LEDs and hopefully generate enough power to charge a cell phone. My sculpture also has a solar panel that will also charge a battery for extra power. Both units will connected to the battery.

First off is this remotely possible and does the flywheel help. I am under the assumption that the flywheel will store momentum and continue to aid in the generating of electricity. Is this correct. I know this will also depend on the DC motor used......I can purchase any size.

Thank you for your help.

....about a total of 12 watts of LEDs.

 

The flywheel will definitely help. You will need to gear up the crank input significantly. Note, this will make the crank more difficult to turn but is absolutely necessary.

Depending on your LEDs, I’d run them at the lowest current possible. Depending on the voltage you can generate in this manner, I’d wire the LEDs in series/parallel. That is 2-3 LEDs in series with a current limiting resistor. Then parallel several of these LED strings to get a total of 12. This will minimize the required current. For example, 12 LEDs @ 20mA in parallel needs 240mA. Using (if possible) series strings of 3 LEDs in 4 parallel groups, only requires 80mA.

A similar device is commercially available. Search on Amazon for “hand cranked flashlight”. You may be able to use one of those, to scavenge and use in your art project.

 

A fly wheel can help the feel of turning it. You may find using a stepper motor for the alternator, and a 3 phase rectifier easy to go with.
I was looking at a Ficher and Paykel washing machine motor running on the wheel of an excercise bike last weekend. It could generate in excess of 200 Watts, but just remember, the user has to crank it over at a pretty reasonable rate to do that.
If you want more that a few watts, a pedal powered on is a good way to go, but a hand cranked unit will work too, but at lower power.

 

The flywheel will definitely help. You will need to gear up the crank input significantly. Note, this will make the crank more difficult to turn but is absolutely necessary.

Depending on your LEDs, I’d run them at the lowest current possible. Depending on the voltage you can generate in this manner, I’d wire the LEDs in series/parallel. That is 2-3 LEDs in series with a current limiting resistor. Then parallel several of these LED strings to get a total of 12. This will minimize the required current. For example, 12 LEDs @ 20mA in parallel needs 240mA. Using (if possible) series strings of 3 LEDs in 4 parallel groups, only requires 80mA.

A similar device is commercially available. Search on Amazon for “hand cranked flashlight”. You may be able to use one of those, to scavenge and use in your art project.

Thank you!

 

A fly wheel can help the feel of turning it. You may find using a stepper motor for the alternator, and a 3 phase rectifier easy to go with.
I was looking at a Ficher and Paykel washing machine motor running on the wheel of an excercise bike last weekend. It could generate in excess of 200 Watts, but just remember, the user has to crank it over at a pretty reasonable rate to do that.
If you want more that a few watts, a pedal powered on is a good way to go, but a hand cranked unit will work too, but at lower power.

I have a gearbox that would do this.

 

Although rather over-kill for 12w, a treadmill motor generally comes with a large flywheel already attached and is an excellent generator.
Max.

 

I see no point in using a flywheel .... It does store energy (in the rotating flywheel) , but that;s no good , you want it turned into electricity ... the function of a flywheel is to smooth out variations in input ....

The key to your project is to get the gearing correct for the motor(generator) 10 or 20 Watts output should be possible

eBay does have some hand generators ....

The motor in the one pictured will only generate a few watts ...

If you want to build one from scratch you need a bigger motor with gearing that makes it hard to turn.

 

If the crank is to be driven by a pedal/treadle then a flywheel will be essential for mechanical reasons. However, step-up gearing will be required between the crank and the motor/generator. Suppose you want, say, 12V out from the generator. A 12V rated DC motor would normally spin at several thousand rpm, so you would have to spin it above that speed to get out 12V when used as a generator.
As for energy storage in the flywheel, I don't see any benefit for electrical generation, since human power (extra pedalling) is needed to get the flywheel up to speed. The battery provides energy storage anyway.

 

A really good example was available, around 40+ years ago, when I was visiting the US. Located in Wanapum Dam, WA. https://en.wikipedia.org/wiki/Wanapum_Dam was a hand driven generator. It was a really good demo showing the effort required to generate electricity. The generator starts up fairly easy to turn, but when you get it up to speed, the volts are enough to pull in a contactor that switches a bank of incandescent lamps into circuit. All of a sudden, it is quite hard to turn!

 

Here's a bigger one ....20W ..... 50 Euroes

https://www.ebay.co.uk/itm/IPRee-Ou...316707?hash=item214dfc89a3:g:sAcAAOSwJ7RcCW-d

 

A gearbox will not really help get more power hand driven than pedal powered. Your leg mussles are stronger that your arm mussels, generally, so that is why you can get more power out. Either way assumes you have apropriate gearing.
I was doing some excercising at our local hospital and we had excercise bikes and hans pedal versions too. The hand ones were VERY hard work!

 

The flywheel is particularly necessary if sudden variations in load is expected, especially hand operated.
Max.

 

Although rather over-kill for 12w, a treadmill motor generally comes with a large flywheel already attached and is an excellent generator.
Max.

I have a treadmill motor ready to go. I'm trying to recycle as much as possible. I thought adding the bigger (24") flywheel would add to the generating capacity. The more lights I can add the better.

Thank you

 

The DC voltage output is dependent on RPM.
The flywheel just dampens any possible variation caused by fluctuating load.
Max.

 

What "sudden variation" ?
We are illuminating 12 Watts of LED's or Charging a Cell Phone
We are not "suddenly" plugging in a 1000 watt toaster.
None of my hand-crank devices have a flywheel - none.
A flywheel adds weight, but will not add any value to this Public Art Sculpture
unless you want to specifically show how a flywheel has Kinetic Energy.

 

What "sudden variation" ?
We are not "suddenly" plugging in a 1000 watt toaster.
.

This was in answer to the OP's question.

I thought adding the bigger (24") flywheel would add to the generating capacity.

 

I would use the flywheel, just be sure to use some sort of “slip” joint so the handle doesn’t keep flailing around after someone stops turning it.

Also for safety reasons I would shield the flywheel.

 

What "sudden variation" ?

How about the sudden variation when the person operating the crank gets tired?

I don’t think anyone was referring to a variation in the load.

 

What "sudden variation" ?
We are illuminating 12 Watts of LED's or Charging a Cell Phone
We are not "suddenly" plugging in a 1000 watt toaster.
None of my hand-crank devices have a flywheel - none.
A flywheel adds weight, but will not add any value to this Public Art Sculpture
unless you want to specifically show how a flywheel has Kinetic Energy.

An educational aspect will add a lot. I was planning to have a small viewing window to show some of the workings.