For those who believe in Miracles a Self Charging Ebike

[flecc]

I'm sure some boffin can make a dynamo that only works on down hill so no extra effort for the riders, even 2 or 3 extra miles for no extra work is worth if you can have it

All been done many times, and on almost every occasion found not worthwhile on e-bikes. There just isn't enough mass or speed involved.

All energy conversions involve loss, so it's far more efficient to use the kinetic energy in the bike to gain downhill sped wherever possible, often helping one into the next uphill or further along the following flat for a while.

The only e-bike system I know of still available with regen is the BionX rear wheel hub motor. That has rider switching of four power levels and four regenerating levels. That regen is not so much useful for gaining current as for the braking effect that nervous riders who don't like high downhill speed find handy.
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[mike killay]

I still have one of those Dynohubs, stripped from a wheel, just tried turning it.
The 'cogging' effect as the magnets pass the poles is noticeable.

 

[tommie]

I still have one of those Dynohubs, stripped from a wheel, just tried turning it.
The 'cogging' effect as the magnets pass the poles is noticeable.

I can spin mine with no resistance whatsoever,

however!

would the uV output from those type be at all worthwhile at over say 50 miles??

 

[Deleted member 4366]

I can spin mine with no resistance whatsoever,

however!

would the uV output from those type be at all worthwhile at over say 50 miles??

Bridge the two terminals to create a load, then see how easy it is to turn.

 

[tommie]

Bridge the two terminals to create a load, then see how easy it is to turn.

You mean turn the lights on, lol?!!
Yes, isn`t that what i`ve been saying for goodness sake!!? The wheel spins effortlessly.

please try and keep up d8..

the effort you talk about expounding is already being put in anyways when you are riding the bike so its not an extra effort,
haven`t you ever ridden a bike with these front hubs??

anyway having said all that its questionable that the current produced would be worthwhile to the modern battery..... although something is better than nothing as they say

 

[flecc]

I can spin mine with no resistance whatsoever,

however!

would the uV output from those type be at all worthwhile at over say 50 miles??

That's the point, the output isn't anything like adequate for charging our batteries. It would just reflect the input you gave when you spun the wheel, a small effort for a small output.
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[mike killay]

You mean turn the lights on, lol?!!
Yes, isn`t that what i`ve been saying for goodness sake!!? The wheel spins effortlessly.

please try and keep up d8..

the effort you talk about expounding is already being put in anyways when you are riding the bike so its not an extra effort,
haven`t you ever ridden a bike with these front hubs??

anyway having said all that its questionable that the current produced would be worthwhile to the modern battery..... although something is better than nothing as they say

I don't think that yours is working.
I have just tried to turn mine
1 Unbridged=distinct cogging.
2 Bridged.=Cogging is even more pronounced.

 

[tommie]

if its not working then why do the lights work when i spin up the wheel??

 

[mike killay]

if its not working then why do the lights work when i spin up the wheel??

Well the only way the lights can work is if they are taking energy out of the spinning wheel. That means that the wheel cannot spin as freely or as long as if there was no dynamo attached.
Bike lights hardly take any electricity. But to recharge an ebike battery will take a lot.

 

[Danidl]

d8veh, not true, don`t you remember those old front hub dynamos? You could hold the bike off the ground and spin the front wheel, it would go on for ever,

similar to this...View attachment 18460

.. the SA hub dynamo is a lovely bit of kit. They were highly reliable, still are, if you have one on a bike, and with very little mechanical drag as compared with the bottle dynamo . However once they are connected up to a load .. a bulb , there is an electromagnetic drag and a spinning wheel will slow down faster than if the bulb is switch off. If you think otherwise, I have these magic beans I could sell you. As a youngster you would have had buckets of energy, and putting 150watts into propelling the bike would be typical. You would not be noticing the 9 watts going into rotating the SA , but you would have noticed the 20watts going into a bottle dynamo.


According to the SA Dyna hub publicity handout it produced 2watts of electric power at 6 volts . Presumably at a sedate pace. If the bike was going faster the voltage would rise and the bulb s glow brighterThe bulbs front and back were rated 1.8w I do recall blowing bulbs on a number of occasions.

 

[flecc]

The newest generation of bike dynamos that come with lighting systems from such as Busch & Müller and Shimano may well have much lower outputs to suit the greatly reduced demands of their LED lighting.

That in turn will mean much lower drag.
.

 

[Kenny]

I changed my standard heavy Shimano dynamo on my Kalkhoff for a lightweight Shutter Precision weighing less than 400g.
The output is quite low at about 3 watts but as Flecc mentioned, that's enough for a good LED light.

It spins smoother than the Shimano, with very little drag, but off course, you still don't get something for nothing.

 

[Deleted member 4366]

You mean turn the lights on, lol?!!
Yes, isn`t that what i`ve been saying for goodness sake!!? The wheel spins effortlessly.

No I don't. I mean what i said: bridge the two terminals.

The wheel cannot spin effortlessly when the lights are on. The SA hub-dynamo is taking power from the wheel and convertijng it into electric power, which slows it down. If you had 2 watt bulbs, you'd have to put in about 6watts to produce that. A casual cyclist pedals with an average of about 100 watts, so that means, you have to pedal 6% harder to get the light out of the dynamo. It's simple physics. the energy for the light has to come from somewhere. That somewhere is you.

 

[Zlatan]

Tommie
Why not connect your magical dynamo directly to a motor...set it spinning, connect elec terminals...and hey presto...perpetual motion...

 

[tommie]

Or how about reading the thread from the beginning, it`s about putting a current back into the battery if possible, and i can assure d8 i didn`t have to put an extra 6% effort into my pedaling just by switching the lights on! Thats in line for `silly statement of the year`! I can also confirm i noticed NO difference whatsoever in cadence or effort,.. possibly you had tightened your front wheel bearings up too tight d8??

 

[mike killay]

Thats in line for `silly statement of the year`! QUOTE]
QUOTE]

Why? have you invented perpetual motion? You cannot get something out without putting something in.

 

[Zlatan]

Or how about reading the thread from the beginning, it`s about putting
So where

Or how about reading the thread from the beginning, it`s about putting a current back into the battery if possible, and i can assure d8 i didn`t have to put an extra 6% effort into my pedaling just by switching the lights on! Thats in line for `silly statement of the year`! I can also confirm i noticed NO difference whatsoever in cadence or effort,.. possibly you had tightened your front wheel bearings up too tight d8??

Please tell us where the energy for the lights is coming from ??? And if it makes no discernible difference to pedalling it certainly wont charge a 400w/h battery.

If folk want longer range on ebike ( the whole point of regen) isn't it cheaper , easier, lighter, and less expensive to simply fit a larger battery...or buy a spare.??
Regen can only make any sense ( and even then debatable) if it is only used during braking..if not Merc, Red Bull, Ferrari have all got it wrong ??!!

 

[Deleted member 4366]

Or how about reading the thread from the beginning, it`s about putting a current back into the battery if possible, and i can assure d8 i didn`t have to put an extra 6% effort into my pedaling just by switching the lights on! Thats in line for `silly statement of the year`! I can also confirm i noticed NO difference whatsoever in cadence or effort,.. possibly you had tightened your front wheel bearings up too tight d8??

Well, if I were you, I would present that dynamo to the Nobel prize committee. You'll probably win the prize for physics because, until now, nobody has ever managed to make a machine that could output more energy than that which was put in. Your name will go down in history and you'll get loads of money, plus all sorts of development grants to improve it.

 

[Zlatan]

You could build a perpetual motion machine aswell. There,s a big prize for that...

 

[flecc]

Tommie
Why not connect your magical dynamo directly to a motor...set it spinning, connect elec terminals...and hey presto...perpetual motion...

That would be very dangerous Zlatan. After powering the motor, the surplus of current from the dynamo would have nowhere to go and would heat up the system and destroy it. It's possibly why we haven't achieved perpetual motion yet, the self-destructiveness of closed loop generating and use systems.
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