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# Power from Pedaling

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#### ashikn

##### New Member
Hi,

I am planning to start a project called "Green power from pedaling". The plan is to install a dynamo in a bicycle with a rechargeable battery to store the electricity generated by pedaling. I want to test if a person drives a bicycle for 1hr, how much electricity he can produce and finally store in the battery.

So I have got mainly two queries.

1. How much a person can generate electricity while peddling a bicycle for 1hr.
2. If i generate x amount of electricity what is the best way to store this power so that i can use it as electricity. (Pls note: I m considering that the Pedaling is not consistent. For example, I will continue pedaling for 10mins then will take some rest, maybe after 5mins again start pedaling. At the end of the day I want to check how much electricity stored)

Also as I have to install the battery in the bicycle and move around for hrs so let me know what kind of battery will be appropriate and also let me know approx weight of the battery.

Finally if I want to do the test for 7-8hrs long, how much electricity can be generated and what kind (power + weight) of battery is appropriate?

Thanks, Ashik

From Wikipedia
In lab experiments an average "in-shape" cyclist can produce about 3 watts/kg for more than an hour (e.g., around 200 watts for a 70 kg rider),

Assuming you are also using the bicycle to go somewhere, the amount of "excess" power will be quite small for a strenuous 1-hr ride.

John

My electricity rates are very high. If I pedal for 5 hours I could save 27 cents.

If you want to store the power from 7-8 hours at 200W, four 50A-h deep discharge lead acid batteries would do it. Figure a total weight of about 150 kg.

400W is near the peak output for a few seconds of absolute effort.
200W might be possible for highly trained cyclists but they are WAY above a normal person's pedaling and aerobic ability!

I would factor *maybe* 50W for a normal person pedaling casually (ie an hour) then maybe 40% total efficiency of the gearing and generator so thats about 20W electrical output.

Which explains why most of those Hippie rigged stationary bicycle generator things put about 1A to 1.5A into a 12v battery, ie about enough to run a laptop.

The reference I have had for many years was that one horsepower is 746 watts and the horse it was referenced to is a good draft horse or work horse.
A human power is roughly about 1/10 of that which put us in the more realistic range of 76 watts and that would be also using a good condition athlete or physically fit person.

For other reference the average human diet is considered to be 2000 calories which is equivalent to 2.3 KWH over a 24 hour time period. Factor in that the base metabolic loads of just staying alive and maintaining body temperature take about 1000 -1400 of it. So in a good day most people can produce about 400 -850 watts of actual work.
There are people who can do more and others who can only do much less as well. Over all I doubt you will find many who can even keep a 75 -100 watt load going for more than a few hours at best. People dont make good power sources!

I dont know about you but sweating and working your butt off all day to provide a few cents worth of electricity doesn't seem cost effective. Especially when you factor in that the converted bike, generator, battery, and inverter needed to turn human power into usable electrical power are going to take a few hundred dollars to build.

Thats probably why the Hippie powered systems didn't catch on either. Hippies are not known for being all that ambitious to start with.

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thanks for your response. So by pedaling for 10hrs I can produce around 1k watt. Now my main concern is the battery and its weight. What kind of battery I should use to store this power and also let me know the approx weight of batteries that can store 500 watt and 1k watt…..

Since you are concerned about weight, the you might consider using lithium polymer (LiPo) batteries. HobbyKing in Hong Kong has good prices for its Rhino brand. Several 10S packs could be connected in parallel to give you the capacity you need. A 10S pack provides 37V for calculation purposes. If constructed of 2200 mAH cells, you could put 10 such packs in parallel to give you 22 AH usable capacity. That configuration would be known as 10S10P. It would require 100 cells and cost about $1900 USD. HobbyKing may give a discount for such a large purchase. Approximate weight is 190g/cell or 19 Kg for the whole pack. On the other hand, three large deep discharge, lead acid batteries at about 30 to 40 Kg each would also work. Local price for me is about$125 USD each.

You will get a lot more exercise charging those batteries than I did doing the calculations. Good luck.

John

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thanks for your response. So by pedaling for 10hrs I can produce around 1k watt.

Only if you're a LOT fitter than me

It's generally considered that a fit man can generate 100W or so on a pedal machine - but I doubt it could be sustained for anywhere near 10 hours.

Bear in mind, it's not gentle pedalling along the flat, it's pedalling up a steep hill in a high gear.

I want to meet the guy who will do 10 hours of hard labor for 12 cents! I have lot of work that needs doing and I will pay very well! as much as a whole dollar an hour if he can work that hard!

I seriously doubt you will find anyone who can produce a full usable KWH in one day on a bike machine.

thn its better to intall a dynamo in my car and store the power in deep cycle lead acid batteries hope this will work.

So weight of battery is main prob....

You're harvesting energy by spending more energy? Why not build a wind turbine instead?

It leads to bigger "cost" questions, doesn't it?

The additional calories, in healthy food, to keep a man working over 10 hours is far more than 12 cents. And that food required fuel and water and fertilizer to grow.

For that matter, I don't think this is appropriate because you're not just adding that the man's job. It's pretty much the purpose of his life because he can't do much else. If you're using people's lives to create power, the slave owner would have to calculate the economics of their ENTIRE daily food budget, housing, etc to generate 100W for 16hr/day.

By the same token, the "green" economist might figure the entire carbon footprint of a man's life from cradle-to-grave and say, ok, we demand that he waste away 10% of his life on the cycle, not doing work at his job, not studying, not resting, not enjoying his family, so we can write up 10% of the carbon footprint of his life as the cost. As such the numbers are astronomically less ecological than simply burning the lbs of coal that it might take to produce the same amount of electricity he produced. Perverse? Yes, but there is some validity to the calculation.

The only place this makes sense is at a gym with a bunch of stationary bicycles. People are going to be there pedaling already anyways, might as well get some use out of them.

Or of course if you do not have electricity at all.

guys actually i m planning to install dynamo n battery stuffs in tourist bicycles so that while tourists move around in the city they will produce some power for national grid. So don’t u think this is logical?

I hv watched in tv; somewhere in Europe they use this kind of bicycle for tourist to product power for national grid. Does anyone know abt this?

Some of us built a system like you are proposing some years ago.
We used a garage sale exercise bike one of us got for $10 and an old truck generator someone else had lying around. For about a good days worth of work we made a human powered generator that could put out about 500 watts for 10 seconds. Then the person would tire out. I dont recall anyone even being able to produce enough power for more than a few minutes to be worth anything. Just charging the old lawn mower battery to the point I could start the garden tractor took me a good 15 minutes of hard pedaling and I almost puked at the end. As I recall we got$15 for it at another garage sale. They guy just wanted the generator but we made him take the bike with it.

guys actually i m planning to install dynamo n battery stuffs in tourist bicycles so that while tourists move around in the city they will produce some power for national grid. So don’t u think this is logical?

I hv watched in tv; somewhere in Europe they use this kind of bicycle for tourist to product power for national grid. Does anyone know abt this?

Never heard of it, but it doesn't sound very practical? - even using a dynamo to power bicycle lights takes considerably more pedalling than without it.

If a million people are riding the bikes, and they produce 2 watt hours per day, then you get 2 megawatt hours. But the costs and losses involved probably makes the scheme totally impractical.

As I recall we got $15 for it at another garage sale. They guy just wanted the generator but we made him take the bike with it. And you can have it back now Dr. Evil neighbor of mine. guys actually i m planning to install dynamo n battery stuffs in tourist bicycles so that while tourists move around in the city they will produce some power for national grid. So don’t u think this is logical? I hv watched in tv; somewhere in Europe they use this kind of bicycle for tourist to product power for national grid. Does anyone know abt this? LOL we spend hundreds and hundreds of dollars trying to put an LiFePO4 battery on a bike to supplement power for quite a few miles. The actual value of the electricity put into them is very low. A really big bike batt can store nearly 1KWH which is worth all of 10 cents. But I don't know how you'd get it out of a biker! Like we said, about 200W is all a fit biker can put out for a sustained period, which he's already using while biking, so asking for even 10W (for 100 hours?) is going to be a very noticeable drag on the bike. He'll either have to do extra work or slow down. Regenerative braking is a great theory, that energy comes "free", but in normal usage very little of a biker's total effort is wasted in braking. Most of it's drag and friction. So if you started out with the battery dead and made someone pedal impossibly hard ALL DAY while biking (+50% extra load, 100W, for 10 hrs!), then you'd get all of 10 cents' worth of power. Never mind the system costs like$1000/bike in parts alone and you haven't built a GTI to deliver that power back onto the grid.

On another note, instead of gaining power while cycling, you could consider regenerative braking.

As you are going to add a generator and battery anyway the weight of the control module may not be very much.

However note that the control modelling is going to be difficult especially to gain smooth braking. Just an idea which was sacked because our college did not have funds to pay for our prototype solar car!

And about integration to the grid... I wont deny that it's possible but the kind of investment needed to provide parking stands/integration ports is going to be really high!(Especially if you need them at regular intervals)

Sadly, we need better batteries or plausible ultracapacitors...

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Hi,

I am currently working on a similar pedal power generator project. However, it is my understanding that when using a battery to store the electrical energy, a charge controller is needed to regulate the voltage between some bounds. These bounds prevent the battery from being damaged. Since the power output of the rider is proportional to the rear wheel rotational velocity which in turn spins the generator creating a proportional voltage, the charge controller bounds the riders power production. My question is: "Is there any cost effective means to store the energy regardless of how hard a person is pedalling?" Or am I just being stupid and there is an easier solution. Any suggestions would be helpful.

Thanks

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