"pedal to charge battery" - better solution needed

[wojtek]

hello,

so far my solution to charge battery by pedalling was as the pictures are showing:
1. small hub motor
2. regen on [0-100% adjustable]
3. pedalling turns the motor and regen gives the resistance

I am looking for a new solution:
1. lighter
2. does NOT need to be waterproof [installing in the velomobile]
3. as QUIET as possible
4. compact size
5. efficiency is NOT important, only doing it to get excersize while cycling. So needs to give me nice resistance to be able to pedal efficiently from training perspective ...

Reason for not using chaindrive - hard to make a nice chainline , now it is VERY loud. + long chain going through the whole velomobile..

thanks for any tips / ideas

 

[mlt34]

Perhaps I'm missing something, but how are you planning on regenning a geared motor? Are you pedalling it backwards, then just using the energy to power a second hubmotor in the rear?

Also, I still don't get why people are playing around with this "pedal to charge" stuff. It's just so terribly inefficient. Let's say you've got a super low power system, maybe 300 watts, that you're happy with. You'll be lucky to sustain 100 watts of continuous pedal power, which due to the second law of thermodynamics will ultimately give you less than 100 watts of energy being stored. When you go to use that energy, your 300 watt system uses it over three times as quickly as you can generate it. That means you've got to pedal more than 3 miles for every 1 mile you want to drive with electricity. If you're willing to pedal 3-5 times as much as you use the motor, why even have a motor at all?

 

[wojtek]

as said clearly in my initial post, i do it only for excercize and dont care about efficiency. I also gave reasons why not using chaindrive..

the two are completely separate, hub motor to power the bike + another hub motor used only as a generator to give me resistance when pedalling [regen fuction permanently on].

 

[dogman dan]

I get what MLT means. Why not just pedal the bike?

But there are some cool advantages. You just pedal the same cadence, same resistance, no matter what. That's nice. But it's so inefficient, it's just somewhat supplementing your range.

I'd be looking at how to just modify a smaller dd motor, like a clyte 400 or aotema. Put a tapered square end on the axles and attach pedals.

You'd end up mounting it in a different location that the existing bb of course.

 

[wojtek]

I get what MLT means. Why not just pedal the bike?

Reason for not using pedal chaindrive:
- hard to make a nice, smooth chainline
- it is VERY loud. Im locked in a fully enclosed velomobile so there is plenty of resonance. The hub motor changed the initial chainline and due to the velomobile structure it is hard to make it run smooth - i spent a lot of hours on it...
- long chain going through the whole velomobile.. The weight of loooong chain, freewheel ect will recompensate for the generator weight.
- no chain inside the velomobile gives me more space for battery / luggage ect...
- no chain = much easier to waterproof the cabin when raining

 

[mlt34]

I totally understand the exercise and training thing; I didn't mean any offense. It just seems like quite an expensive electric bike for a bike that is barely being used as an 'electric bike'.

Do you really want to use the motor power every now and again? What if instead of making it an ebike, you used it to power other things? You could charge your phone/tablet/flashlight etc while you're riding (or once you've come back and put it in the garage). You could plug something into your bike once it's back to power your lights in your garage, or run small appliances, etc. The bike would essentially be your own human powered generator.

If you're in good enough shape to not only pedal around but actually be creating surplus usable energy with your pedaling, I have to wonder how often you'll want to be powering the bike by motor instead of by wojtek anyways.

 

[mlt34]

I get what MLT means. Why not just pedal the bike?

Reason for not using pedal chaindrive:
- hard to make a nice, smooth chainline
- it is VERY loud. Im locked in a fully enclosed velomobile so there is plenty of resonance. The hub motor changed the initial chainline and due to the velomobile structure it is hard to make it run smooth - i spent a lot of hours on it...
- long chain going through the whole velomobile.. The weight of loooong chain, freewheel ect will recompensate for the generator weight.
- no chain inside the velomobile gives me more space for battery / luggage ect...

Those are all very good points. I didn't think about some of those. So this would basically be a high tech and somewhat expensive replacement for a chain drive? You aren't storing this power as much as you are instantly sending it to the two real motors?

 

[wojtek]

thanks!
i ride to work everyday, total distance around 75kms. It takes 1,5-2h of riding. Perfect time to get excersize. Dont want to waste it by just sitting in the velomobile and do nothing. Pedal to power the velo would be great but it is just a nuisance to make it work quiet

I was thinking to either pedal to generate power back to main pack [75v or 100v max V] or to power 12v for lights, horn ect...
To be more clear, at the moment on the other bike, im using 2 controllers and 2 motors. 1 battery pack. The generator motor puts energy back to the battery pack same way as regen braking does.

Was hoping to get some ideas from you guys, not really to discuss IF it is good idea or not

 

[dogman dan]

And I gave you my best idea. Put pedals on a dd motor somehow. no chain.

It would work just as well with other kinds of motors, but you would still need an axle that protrudes from both sides that you can weld a cut off piece of a square taper bb onto. The motor that makes sense with to me, is a 400 clyte or aotema, in front hub.

Maybe you just don't visualize it from words. Take a front motor, put pedals on it somehow. bolt the body of the motor to the bike rather than the axle.

 

[wojtek]

OK i got it - great idea !! will think if i can do it with my specific vehicle. Thanks

 

[wojtek]

now that I think about it... how do I solve the problem with wires coming out of motor?

 

[xenodius]

http://www.hupi.org/HPeJ/0015/SeriesDriveHybridVelomobiles.pdf

It makes some sense.

 

[wojtek]

thanks - this is EXACTLY what i need!!!! i dont think it is in production but will do more research. If only it runs quietly..

 

[wojtek]

here we go: pedal chainless alternator to recharge battery: http://www.mandofootloose.com/eng/product/technology.asp

 

[Lebowski]

here we go: pedal chainless alternator to recharge battery: http://www.mandofootloose.com/eng/product/technology.asp

from an efficiency point of view pretty pointless...

 

[wojtek]

yes yes i know

but again im NOT after efficiency but excersize, i have 100v 30ah of lipos inside!!!

Reason for not using pedal chaindrive:
- hard to make a nice, smooth chainline
- it is VERY loud. Im locked in a fully enclosed velomobile so there is plenty of resonance. The hub motor changed the initial chainline and due to the velomobile structure it is hard to make it run smooth - i spent a lot of hours on it...
- long chain going through the whole velomobile.. The weight of loooong chain, freewheel ect will recompensate for the generator weight.
- no chain inside the velomobile gives me more space for battery / luggage ect...
- no chain = much easier to waterproof the cabin when raining

 

[Lebowski]

I know where you're coming from my 'pointless' coment was regarding the vehicle in the link, not your velomobile. I understand
what you're after, so... I like what you posted in the very first post of this thread, the belt drive must make it pretty quiet, but I
assume there's no room for this in the velomobile ? You could build an AF generator on the pedals.... or what would be nice to try
one is to have a human driven belt covered in alternating magnets, and pass those over some (fixed) coils. Or attach a disk covered
in magnets to the pedals, and rotate this over a copper disk (so braking based on eddy currents, I think this is how simple gym machines work)

 

[wojtek]

I know where you're coming from my 'pointless' coment was regarding the vehicle in the link, not your velomobile. I understand
what you're after, so... I like what you posted in the very first post of this thread, the belt drive must make it pretty quiet, but I
assume there's no room for this in the velomobile ? You could build an AF generator on the pedals.... or what would be nice to try
one is to have a human driven belt covered in alternating magnets, and pass those over some (fixed) coils. Or attach a disk covered
in magnets to the pedals, and rotate this over a copper disk (so braking based on eddy currents, I think this is how simple gym machines work)

thanks Lebowski
i dont have much technical skills and workshop to build such thing unfortunately hence looking for more ready to use one.

The problem is to find a very short belt to reduce the distance between crankset and motor - if i had one, then there would be enough space for same solution inside velomobile as on the other bike.. If there is no better solution , i will just copy the idea from my catmobile to velomobile.

 

[wojtek]

I called optibelt but they don't do custom length belts

 

[Lebowski]

how about you use a chainring on the pedals (so, standard) but then just from an alu plate and an old chain build a socalled cage gear to turn the generator?

 

[wojtek]

OK i think i manage to get custom length belt.. so would need to get lighest possible DD motor.

+ waiting for further tip from Dogman about his idea of putting pedals on motor axle. Wiring out of motor is one issue i see, and another is the motor RPM..

 

[wojtek]

how about you use a chainring on the pedals (so, standard) but then just from an alu plate and an old chain build a socalled cage gear to turn the generator?

good idea I think this could be a loud solution and a bit complex for stupid me.

 

[dogman dan]

Re the wires exiting a hubmotor converted to a pedal generator. Duh, now I see why that idea would not work. If the stator rotates, the wires do too. You'd need a motor with only the magnets on the axle rotating and the phases on the stationary ring.

To quiet what you have now, perhaps a toothed rubber belt rather than chain?

 

[wojtek]

To quiet what you have now, perhaps a toothed rubber belt rather than chain?

im using 'belt right now - however it is difficult to find short one. As you see on the pic in first post, the belt is far too long. Trying to get custom lenght one from a different source than optibelt...

 

[wojtek]

http://www.aliexpress.com/item/bike-pulley-for-back-wheel-and-bike-belt-driver/742174322.html
http://www.aliexpress.com/item/free-ship-bike-crankset-for-bike-belt-drive-at-good-price/809914044.html