Dynamic breaking - products - developments -

[eventoura]

Hello,

i would like to hear some feedback about the follwing idea:

i am driving in a german town called "bielefeld" something like a "fixie"? ( a very cleaned fast bike for the city )
i want to build a e-storage with some caps which is loaded by breaking
and then just give me the little speed to approach
and for not having to shift a gear (there is no gear )
and not to wearout the mechanical brake pads

so all in all a very small application...

are there any products u know? or ideas for realization?

thank you

 

[Nanoha]

Probably not worth the extra weight, cost and complexity.

 

[eventoura]

complexity: yeahperhaps ....the point is to get the generator roll free if i dont wanna use it...i am thinking about a hub gear in the front wheel where u can choose between freewheel and generating, selected by the pulling the break.....

costs: i have all the parts from junkyard( bike industry is near around)

worth: is my (palate?) so but u can generate power for phone, lights etc. and the perfect break

 

[gogo]

Since I was aware of past discussions relating to your question, I searched on the term "energy recovery" and found these two threads:

http://endless-sphere.com/forums/viewtopic.php?f=2&t=7891

http://endless-sphere.com/forums/viewtopic.php?f=6&t=7511

eventoura, it would be great if you could summarize how the information in those threads pertains to your question and/or answers it. I'd guess the short answer is as stated by the previous post:

Probably not worth the extra weight, cost and complexity.

[EDIT] I think there have also been discussions of mechanical spring types of energy recovery/release.

 

[hjns]

Hello,

i would like to hear some feedback about the follwing idea:

i am driving in a german town called "bielefeld" something like a "fixie"? ( a very cleaned fast bike for the city )
i want to build a e-storage with some caps which is loaded by breaking
and then just give me the little speed to approach
and for not having to shift a gear (there is no gear )
and not to wearout the mechanical brake pads

so all in all a very small application...

are there any products u know? or ideas for realization?

thank you

I thought about this a lot (more than 60 seconds, at least), and this is how I would do it:

• Build your e-storage with caps or batteries.
• Use a dynamo connected to a brake handle to toggle it on or off.
• The resistance of the dynamo will act as a brake.
• The dynamo will charge your caps / batteries. Note that most dynamo's generate AC at 6V, so you may need a DC-DC converter as well.
• Use the charged caps / batteries to pump energy drink (Red Bull?) from your backpack into your mouth
• Use the extra energy to get the little extra speed.

Just to be clear, with my cromotor and a very very generous regen on long hills, I get maximally 10 Wh of capacity back. And this is only after I have spend more than 800 Wh in order to get to the speed where my regen is functional.

 

[dogman dan]

If you pedal fixie style now, you won't want the weight of it. Caps won't work good enough, so you'd have at least a pound of battery weight, plus the heavy ass copper in the generator/ motor.

Hell, if you pedal a light bike, you'll really hate adding as much as 5 pounds. But if you don't mind the weight, some kind of friction drive would be the starting point imo. Something that dropped the friction drive wheel to make power when you grab brakes, then requires you to grab another lever on the bars to raise it again once you get to your target cruising speed.

The real rub here, is that you will need to brake ten feet, to make enough energy to go 1 foot. So unless you include enough battery storage to provide the other 90%, you won't be going far on the stored energy. For this reason, most that want a lighter bike to provide assist, just install a small planetary gearmotor on the rear wheel. Then it freewheels for pedaling, but it's there at a touch of throttle when you need it. You could do this with a little as 10-15 pounds extra weight. But you completely lose that super light fixie feel of the bike. But even so, you might like assist enough to carry the weight to use it a lot.

 

[eventoura]

First of all thank you for your answers... you probably realized that my idea is actually growing (and not immovable or even not ready for take off)

but i think there is a misunderstanding: my preference is to break without mechanical contact...and then i want to use the energy (for whatever)

in my version i will just have a little push after breaking...

pulling the break will get the coil into the field of the magnet...current is induced... loading cap...break is let off :
1. case you pedal ...the coil is released/ pushed back by spring

2. case i push a throttle... the coil is drained by the current in the other way round.. and i get a little push forward till the resistance of the magnets are greater then the force by the coils and the coil is released back

hope u can see it

 

[dogman dan]

I get it. You'd move the coils into the magnet when you wanted braking. Then out to roll, getting a freewheeling effect. Sounds cool.

The problem with a normal direct drive hubmotor is you are always in dynamic braking, unless you add power to it. With a geared hubmotor, the freewheeling prevents dynamic braking.

I just assumed you wanted to use the stored energy to get going again. We get a lot of people here, getting into the fantasy that you will get 90% of the energy back, instead of 10%.

 

[MadRhino]

I see interest in this only if it is mechanical, light weight and as direct as can be.
A Titanium spring in a freewheel hub, loading at braking, immediately unloading at take off.
That can be done around 400g, with better efficiency than electric, and would be interesting for pedal bikes.

 

[Joe T.]

We get a lot of people here, getting into the fantasy that you will get 90% of the energy back, instead of 10%.

So to clear things up. Re regenerative breaking, if done right, can get you as much as 10% back? Seems like a lot of work.

 

[Hillhater]

since we have learned that the energy harvested is insignificant, and since the OP already rides a "fixie" such that he doesnt need brake pads, ..i dont see much to be gained from this...other than weight and complexity !