# Pedal Powered Electric Motor (hypothesis)



## nich (May 6, 2011)

First of, I am a novice in EV’s. 

I would like to find out, what motor (in terms of KW output) can be powered by 12 - 15v dc generated by pedal power, inverted to 110v or 220v ac (Not sure how many watts. Does the watts depend on the inverter? Or What).

Depending on the type of motor than can be powered will determine the application of the motor. 

If need be, multiple pedals can be grouped to multiply the output.

I found a pedal power kit with these specs:

Generator Output Range: 0 to 40VDC
Typical Output: 15 Volts DC
Peak Current:  20 Amps
Peak Watts: 300 Watts
Generator Internal Resistance: ~0.35 Ohms
Rated RPMs: 2800

So, is it possible to power an AC electric motor? If so, what KW would that motor be? Can an EV be built out of this?

Reason behind this is that batteries are expensive, while the range is low, while many of us are well capable of peddling for an hour, then rest at a restaurant to enjoy some refreshments and some food before taking the pedal again. We become the battery. Wouldn’t it be neat if that pedal powered EV would be light, aerodynamic and powerful enough to reach 100 km/h. This would mean that long distance travel could be accomplished, while improving health / fitness. If it’s a multi seat EV, then each seat can have its own pedal. 

Will appreciate your input to know if this is possible.

Thank you.


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## Yabert (Feb 7, 2010)

The hard reality is:

If you are in good shape, you can probaly generate around 1/4Kw with your legs. So you can't powered the motor with more than 1/4Kw (a bit less if you consider efficiency lost). A normal bicycle will be more efficient than your idea.

You best chance to reach 100 km/h for one hour is to build a realy aerodinamic and light 20 seats ev.

Or I thinks this one is nice: http://www.youtube.com/watch?v=MjEKi9D2hh0&feature=youtu.be


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## TigerNut (Dec 18, 2009)

If your legs look like this, you can possibly average 300 to 350 watts for an hour (with apologies to Thomas Voeckler if I got that wrong by more than 20%). World-champion track racers can put out about 2000 watts for 30 seconds. 

If you're going to try to ride a bike then having an electric transmission will not help you any...


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## frodus (Apr 12, 2008)

I'm having a hard time understanding why.....

You want to convert mechanical to electrical DC, electrical DC to electrical AC, then electrical AC to mechanical again.

Why not just go mechanical to mechanical?

Each time you convert, you add losses.


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## Pi3141 (Jan 17, 2010)

Hi nich,

perhaps you could look at this design by Cedric Lynch - he is the designer of Lync Permanent Magnet motors but he know trades as Agni motors from India.

Anyway here's his idea.



> Meet Cedric Lynch
> www.agnimotors.com
> Designer of very respected electric motors
> Builder and pilot of this super light electric bike which requires about 2 hp to cruise at 60mph.
> ...


Perhaps you could look at something similar, with a light battery pack and retain pedals for some pedal power.


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## Yabert (Feb 7, 2010)

Yeah!

That's the way to go...... the power of your leg directly move the vehicule and the small battery give power to the motor to help you move the vehicule!


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## Pi3141 (Jan 17, 2010)

Lynch design used 4 yellow tops weighing 11.7Kgs each and a PM motor at 11Kgs, plus controller etc. That’s over 58Kgs of weight, plus the vehicle itself. The Thunder Sky's are about 3Kgs so 14 would be 42Kgs plus the motor, 53Kgs total, plus the vehicle.

He's getting 175 miles at 40 mph so it would be conceivable to reduce the batteries, reducing the weight and making it possible to use pedal power when necessary but still have a useful EV. 

Cedric lynch said it was possible to run the vehicle on 2 hp but it was sluggish up and down hills. 2 hp is way more than a person could manage according to Tigernut’s post.

300 watts equals 0.41hp

If Lynch is now getting 175 miles on 14 cells, you could reduce his specs by a quarter to get an idea, use 4 cells weighing 12Kgs plus 11Kgs motor, reducing weight being roughly proportional to horse power required to power it, you would need 0.5 hp to get similar sluggish uphill performance and roughly 40 miles range. It would probably be less range, its rough estimate. 

The EV equipment would weigh about 25Kgs plus the bike.

Best to build it as a trike, 2 wheels at the back for stability, especially when peddling.

Something like - 

Hase Klimax 2K











It would still be quite heavy so pedal power would probably only be used for emergency and in short duration or if you wanted a good workout.

If you could design it so the batteries detached easily then when required, you could remove the batteries leaving the motor and controller on the bike and still use the bike as standard pedal power (although with a little extra weight from the motor etc)


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## redorblack (Feb 14, 2011)

Pi3141 said:


> Lynch design used 4 yellow tops weighing 11.7Kgs each and a PM motor at 11Kgs, plus controller etc. That’s over 58Kgs of weight, plus the vehicle itself. The Thunder Sky's are about 3Kgs so 14 would be 42Kgs plus the motor, 53Kgs total, plus the vehicle.
> 
> He's getting 175 miles at 40 mph so it would be conceivable to reduce the batteries, reducing the weight and making it possible to use pedal power when necessary but still have a useful EV.
> 
> ...


It's conceivable to reduce the AH of the battery pack, but most batteries designed for EV usage suck when you look at their C rating (how hard you can draw the power off of them). To have a battery pack with a low C rating like Thundersky LiFePo4, you need enough capacity in AH to cover the amps you are going to draw constant and burst. So if you are using a 200amp controller, you need batteries that are safe and will live a long happy life when loaded at 200 amps. If you have a 100AH pack of batteries that can only safely be drawn down at 1C (1 x the cells AH capacity) you can't load it past 100 amps. If it is a 2C battery, you can draw that 100AH capacity at a rate of 200 amps (but it'll only last you about 1/2 hour). If you step up to LiPo Turnigy Nanotech packs, you can draw at 45-90C... so your 100ah pack can safely supply 4500-9000amps! Of course the most badass controllers on the market only can utilize 2000amps, but you wouldn't even get one of those batteries warm at that load. For something like a drag race application where enough to get you to the other end of the track, or your example where you want to lose weight at the cost of range, you could cut that down to a a way smaller pack and still get the desired results without killing the pack. A lot of the electric assist cyclists are going that route, very powerful little R/C motors and tiny light LiPo battery packs that can easily accelerate you up to 40mph or a steep hill... but instead of lasting 20 miles, they only care to go maybe 5-10.

Electric assist pedal bikes are a reality... there is one human power assisted 'car' on youtube that is mostly bs as you row to power a generator in a car that can go 50+mph. There is no connection between the human input and the wheels... you are just powering a generator that puts your pitiful 1/4 hp or less back into the batteries... most likely about 100 watts worth. But the car is probably pulling about 6-14,000 watts, so your input is less than what the lighting probably draws.


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