Anyone ever tried to implement regenerative braking?

danielrlee

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May 27, 2012
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danielrlee

Esteemed Pedelecer
May 27, 2012
1,373
709
Westbury, Wiltshire
torquetech.co.uk
While I'm here, my thoughts on regen:

Regenerative braking is not worth basing a whole build around.

However, if you feel that a direct drive motor is the the right type of motor for you due to its reliability and high power capability, regeneration is a nice extra that is definitely worth implementing.

IMO, the main advantage to regeneration isn't the recaptured energy, but the maintenance free, buttery smooth, anti-lock braking that it provides.
 
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guerney

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mr_ed

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While I'm here, my thoughts on regen:

Regenerative braking is not worth basing a whole build around.

However, if you feel that a direct drive motor is the the right type of motor for you due to its reliability and high power capability, regeneration is a nice extra that is definitely worth implementing.

IMO, the main advantage to regeneration isn't the recaptured energy, but the maintenance free, buttery smooth, anti-lock braking that it provides.
Thanks…it would be a tough decision for me to base a build around a hub motor (awaits flack) because I think the mid-drive works so well. I've got an 11 speed cassette geared for 40mph flat out and about 4mph in 1st gear, gets me up all hills even on about 150W.

I think my ultimate drivetrain would be a frame integrated mid-drive, with an integrated CVT gearbox (unless motor has torque/power/rpm range to not require this), regen capable with a locked belt drive back back to the rear hub, battery and wiring integrated into the frame. Display and controls via a smart phone mounted on the bars. Support for a standardised EV charger plug. Hopefully e-bikes will evolve in this direction…

Sounds like a cool project for a university engineering course, a bit like the formula student competition.
 

guerney

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You'll have to wait and see.
Spinning on top of your bike helmet? One strapped to each arm? One at each corner of a bike trailer? A seventh on the rear pannier rack?
 

saneagle

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Spinning on top of your bike helmet? One strapped to each arm? One at each corner of a bike trailer? A seventh on the rear pannier rack?
That's what all the plebs would do. Remember, there's genius at work here, and I have a reputation to keep.

Have you ever heard of a wind concentrating wind turbine? If that cart thing above had used one, he might have been able to go even faster.
 

guerney

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Have you ever heard of a wind concentrating wind turbine?
That's not a...

Ugrinsky type

That's what all the plebs would do. Remember, there's genius at work here, and I have a reputation to keep.
I'll be very disappointed if your bike will look sillier than mine.

A TSDZ2B draws less amps ascending hills than a hub motor, and it's selection is starting to make sense if this is the same secret project you've mentioned before.
 

mr_ed

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Feb 15, 2022
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Just going back to my original post... I plotted my route up in the Trip Simulator and tweaked parameters until it matched my consumption. Then switched on regen and given the hills and speeds it thinks I'd get about 10% from regen.

If I pedal harder, putting more watts in, then I get significantly more back from regen.
I've put an average of 75W in, if I increase that to 100W then my regen goes up to 15%. 150W gives me 38% regen! If I put more power in then the motor has to do less, the battery output is less, but the input from regen is pretty constant as it only really depends on the downhills and the speed I'm doing as I come over the crest hence the percentage is higher.

Without regen, the mechanical brake is doing about 100Wh of work, with regen its doing nothing.

Interesting tool!

 

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danielrlee

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May 27, 2012
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Just going back to my original post... I plotted my route up in the Trip Simulator and tweaked parameters until it matched my consumption. Then switched on regen and given the hills and speeds it thinks I'd get about 10% from regen.

If I pedal harder, putting more watts in, then I get significantly more back from regen.
I've put an average of 75W in, if I increase that to 100W then my regen goes up to 15%. 150W gives me 38% regen! If I put more power in then the motor has to do less, the battery output is less, but the input from regen is pretty constant as it only really depends on the downhills and the speed I'm doing as I come over the crest hence the percentage is higher.

Without regen, the mechanical brake is doing about 100Wh of work, with regen its doing nothing.

Interesting tool!

Why on earth would you want to pedal harder in order to increase energy capture into the battery? Why not just use the pedals to power the bike directly, without any of the conversion losses, complexity and engineering challenges involved with regenerative braking?

Don't get me wrong, I'm a big fan of regen. Just not for it's energy recapture capability.
 
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mr_ed

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Why on earth would you want to pedal harder in order to increase energy capture into the battery? Why not just use the pedals to power the bike directly, without any of the conversion losses, complexity and engineering challenges involved with regenerative braking?

Don't get me wrong, I'm a big fan of regen. Just not for it's energy recapture capability.
Ha, no I'm not saying you'd pedal harder deliberately to get more regen... I just experimented with tweaking a few parameters to see the effect on regen and was interested to observe this. I think its mostly the regen as a percentage is increasing because you're consuming less watts from the battery because you're pedalling harder. The absolute watts regen only slightly increases, which I assume is because you're crossing the crest slightly faster and going slightly faster when you start regen.
 

flecc

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Oct 25, 2006
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I think my ultimate drivetrain would be a frame integrated mid-drive, with an integrated CVT gearbox (unless motor has torque/power/rpm range to not require this), regen capable with a locked belt drive back back to the rear hub, battery and wiring integrated into the frame. Display and controls via a smart phone mounted on the bars. Support for a standardised EV charger plug. Hopefully e-bikes will evolve in this direction…
The direction of not being in any way still a bicycle. :(
.
 

saneagle

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It has two wheels, a saddle, pedals and handlebars... I'm not suggesting a throttle lever.
What does it need to make it a bicycle?
It has a crank motor, which is fundamentally shite, so it makes the whole idea shite, just like regen for a bicycle. When you try these things for yourself instead of writing about them, you quickly realise why.
 
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flecc

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It has two wheels, a saddle, pedals and handlebars... I'm not suggesting a throttle lever.
What does it need to make it a bicycle?
Stripping of all you suggested.

The perfection of the invention of the bicycle was its simplicity combined with incredible efficiency and the reward of the pleasure that cycling gives.

Every power assisted bicycle loses that perfection and the more that it is refined in the manner you suggest, the more it becomes a motor vehicle, the more it loses the pleasure of truly cycling.
.