# bike/crank generator

Solar Expert Posts: 57 ✭✭✭✭
does anyone have any info or blueprints on how to build a bike powered or hand crank powered generator or if it would generate enough electricity to justify buillding one? i was wanting one to use with my solar generator

• Solar Expert Posts: 251 ✭✭✭✭✭✭
Re: bike/crank generator

watch this video for an idea.... http://www.youtube.com/watch?v=a-7iSmC4s5A ....
Re: bike/crank generator

The most you will get out of a typical person is 100-200 watts for maybe 20-40 minutes (depending on the person).

200 watts * 1/2 hour = 100 Watt*Hours (0.1 kWhrs or ~\$0.01-\$0.03 of electricity @ \$0.10-\$0.30 per kWhr)

Is it worth it? A 40 watt solar panel will generate as much, or more power per person on a sunny (no-winter) day in most places.

40 watts * 0.8 panel derating * 4+ hours of full sun = 128 Watt*Hours

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 413 ✭✭
Re: bike/crank generator
BB. wrote: »
The most you will get out of a typical person is 100-200 watts for maybe 20-40 minutes (depending on the person).

200 watts * 1/2 hour = 100 Watt*Hours (0.1 kWhrs or ~\$0.01-\$0.03 of electricity @ \$0.10-\$0.30 per kWhr)

Plus the cost of food. Extra food. Lots of extra food. When I was a serious cyclist, I ate 9,000 calories a day. That's 4 1/2 times normal -- but at least I was in shape!
Is it worth it? A 40 watt solar panel will generate as much, or more power per person on a sunny (no-winter) day in most places.

40 watts * 0.8 panel derating * 4+ hours of full sun = 128 Watt*Hours

-Bill

The total cost equation requires looking at ones motivation. If it's a camper or campsite power system, yeah, a bicycle power generator might make sense as a way to charge batteries for some night time lighting. Otherwise, solar panels or small wind turbines.
• Solar Expert Posts: 953 ✭✭✭✭
Re: bike/crank generator

Julie,
Did the spare time you didn't spend on a bike go towards shopping, cooking and eating? 9000calories a day? What time did you have for study or work? Usually anyone eating that much you see on Dr Phil or Oprah!

The science centre in Toronto where i grew up had bicycle generators for demonstrations. You could pedal your guts out and light a bulb or maybe light up a little crt screen. Here's a fun link on just this topic:

Ralph
• Solar Expert Posts: 57 ✭✭✭✭
Re: bike/crank generator

wait, wouldnt the type of dc motor you used determine how many watts that it would produce?
Re: bike/crank generator

Sort of... A permanent magnet motor would tend to be more efficient as it does not have to generate a magnetic field too (around a 10% or so improvement?).

Then you get into DC motors (various types, series wound, shunt wound with comutators) vs alternators with rectifiers, etc...

With many PM type motors, they tend to have a "cogging" effect as they turn. May or may not be irritating.

It is not a trivial solution--but there are lots of opportunities for learning. The differences between the various types is probably less important (efficiency wise) vs the RPM and IV curve (current voltage) of whatever type you choose. Typically, the more gearing (input:output ratios)--the more mechanical inefficiencies you have.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 453 ✭✭✭
Re: bike/crank generator

Bill,

The "Cogging" affect, do you mean the resistance of the magnets to the stator as the rotor turns ?

For instance, I have both kinds in my PMA's. One has magnets studded into the rotor lobes and the other has a solid round magnet inside the lobes on the shaft itself.

The magnet on the shaft of rotor spins without the "Cogging" affect. The other is harder to turn because it's attracted to the stator phase plates when they pass by. This one seems to produce more power at lower rpm.

With the crank generator, depending on which type you use, will give you more of a workout or more of an output at higher crank speeds.
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