Pedal Power Generation

[WADMW]

Hooking up an alternator or a dynamo you can produce electricity, what if several alternators are used for a single bicycle, is it possible to increase the current generated?

 

[MintJulep]

If you want to increase the current all you need to do is lower the voltage.

 

[byrdj]

You will need to add more peddles as with increase in current it gets harder to peddle.

It has been decades since I tried one of those electric company demenstration bikes where you see how many 100 w light bulbs you can have switched on. I seem to remember about 3 was all I could do

 

[BrianPetersen]

Original poster needs to remember the laws of thermodynamics. You can't get more power out of something than you put in.

A 1000 kW generator will not generate 1000 kW using the power input from a bicycle.

A thousand 1 kW generators will not do any better than one 1000 kW generator in that respect.

If you have a more realistic generator size of a couple hundred watts which is reasonably well matched to the amount of power that a person can deliver, two of them won't generate any more.

 

[3DDave]

Usain Bolt is producing under 1000 watts for a few seconds with most of it wasted as friction inside the muscle sheaths and expelled as heat.

Average person might get 75 watts for a day shift.


As Mint Julep mentioned, higher currents are achieved by lowering the voltage, but eventually the resistance of non-superconducting materials will limit the current by setting a minimum level on the voltage by setting a minimum level on the resistance, particularly within the electrical generator. There will also be magnetic losses that set a lower level on that part of the operation.

 

[JStephen]

It is common for cyclists interested in high performance to measure their power output, and special powermeters are made for that.
There are also several on-line bike power calculators that can estimate power based on average speed, etc.

So, for example, using this one:

http://www.bikecalculator.com/

On my ride today, it looks like I averaged about 108 watts over about 9 hours of pedaling.
On my ride Tuesday night, I averaged about 175 watts for a hour of pedaling.
On my ride a couple of weeks ago, I averaged about 217 watts for 20 minutes of pedaling.
I'm a reasonably large person who has done quite a bit of bicycling, so if you're using smaller people and/or people that don't regularly bicycle (or even exercise), expect correspondingly less power output.

If you're using a cyclist to generate power, a well-designed system for that might be fairly efficient. A home-brew cobbled-together system might be fairly INefficient, so factor that in as well.

If you want me to sit in a room and crank out 175 watts for an hour, you'll need to have a big fan running, and you can expect a major puddle of sweat under that bike when I'm done, those watts don't just pop out by themselves. Also, that bike needs to fit properly for that to work.

If you're interested, this'll give you an idea of what that "217 watt" effort looks like, from 4 or 5 years ago. This was riding around a 0.9 mile loop as fast as I could. I've seen crit racers make this loop at 28 or 29 mph, I was doing about 21, I think.

https://www.youtube.com/watch?v=bTD3xOyBrbU

 

[IRstuff]

Moreover, asking the same questions over and over again will not result in any different answers from this site, since most, if not all, are actual engineers who understand conservation of energy, etc.

Your previous posts, in case you've forgotten that you've been trolling for answers to your liking for over 4 months:
thread404-411868
thread404-408980
thread404-406154

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529

 

[Artisi]

might be in order

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)