Self-charging ebike?
 

Is this too good to be true? The claim is that this bike recharges with regenerative braking and stores the energy in super-capacitors. I'm no mechanical expert or physicist, but it seems to me that there is only a little bit of energy available from braking.

What do you think?

It sounds like a good concept, and I can see the technology advancing. It seems like there is still more effort required on the part of the rider. That can be a good or bad thing, depending on the type of rider you are, I guess. Some assist on a short hill would help many people, while still providing more of a workout pedaling on the flats. It would be interesting to see the available watts/hour output of the supercapacitor pack, as well as the weight vs a comparable li-on battery pack.

Interesting...I have read that regenerative braking on bikes is not worthwhile owing to the significant additional weight for the motor to be able to also generate power. Perhaps this French group has made improvements in this regard. However, from Wiki...

Supercapacitor/battery combinations in electric vehicles (EV) and hybrid electric vehicles (HEV) are well investigated. A 20 to 60% fuel reduction has been claimed by recovering brake energy in EVs or HEVs. The ability of supercapacitors to charge much faster than batteries, their stable electrical properties, broader temperature range and longer lifetime are suitable, but weight, volume and especially cost mitigate those advantages. Supercapacitors' lower specific energy makes them unsuitable for use as a stand-alone energy source for long distance driving. The fuel economy improvement between a capacitor and a battery solution is about 20% and is available only for shorter trips. For long distance driving the advantage decreases to 6%. Vehicles combining capacitors and batteries run only in experimental vehicles.

Depending on riding habits, some will benefit from regenerative braking many times more than others. Some (including me) conserve momentum and barely touch the brakes. Others go full speed into corners and brake hard. Some just have cross streets at the bottom of hills.

EDIT - You can multiply all that by about 3 as well because there's skinny little girls on light bikes all the way up to heavy people......

Yes. Next question?
The energy recovered by decelerating can be used to accelerate a little, but it's subject to loss in both parts of the cycle, and you're still going to be needing friction brakes at times. So in stop-start traffic it might be useful but you'll only get maybe 70% return on a good day. The video said that the generator is running on the flat, so you'll be pedaling harder or riding slower on the easy parts of the route - this suggests that you'll feel the benefit more on a route that has a lot of up & down hills rather than mostly flat.
I think if you use a regular e-bike to assist in the same way that the regen bike does you will go a long way before a recharge anyway. Lithium needs to be recycled, there's a lot going to landfill and that's a problem, but I don't think supercaps can replace chemical batteries any time soon.
edit: maybe it would be more useful to develop regular e-bike "smarts", so they do the adaptive assist rather than depending on the user clicking up and down the assist level button.

the energy has to come from somewhere. on a car you have several thousand pounds of mass to slow down which charges the battery thru regen braking

on a bike with rider you have 200-250 pounds AND the extra weight of the batteries and charging unit (which have to be accelerated, ridden uphill etc)

Also would require a more complicated hub assembly for the regen brakes.

I don't think there's enough net energy recovery to offset the additional weight.

/markp

I wouldn't expect a permanent magnet direct drive hub would need anything more than an additional switching circuit to turn a basic motor into a regen system BICBW.

Better idea; regen from bike suspension movement, potentially including frame, seatposts, and stems. Unlike braking, vibration from the road is more or less constantly present.

The power-generating apparatus would mitigate or even eliminate the need for oil or air damping. Might encourage a move back to 23-mm tires at 140 psi.

Future RockShox executive: you read it here first. Pay up.

Reclaiming energy from braking and converting it into electricity was something we figured out well before the turn of the century. So not really anything new here. And if you are thinking this makes a bike a perpetual motion machine and it won't need charging... well nothing new here either. Plenty of people wrongly believe they can make a perpetual motion machine. I met one once.

Holy Crap!! I just linked this video in another forum. I wouldn't classify it as "self-charging", since there are no batteries. But I'm interested to hear more about it, just out of curiosity, because there is no way I'm purchasing an electric bike. However, I understand how some can look at it that way. I do like the use of simple capacitors in lieu of batteries. Although they admit there are issues for climbing, which they are working on.





:speedy:

Garmin is making several models of watches and bar mounted GPS devices that have a solar lens that can partially recharge the device.

It vastly improves the battery life but even in full sun, cannot keep the device away from a charger forever.

That is a tiny device with a tiny battery.

Now let’s upsize this to an e-bike. 600w motor, 52v battery, and realistically, 3-5 hours of runtime. Even with regenerative braking and solar panels, how much could it possibly charge? Probably very little in the scope of a battery that size.

It might make the difference between coasting home to the charger and pedalling analog on a dead bike.

I’d like to know how much less effort the woman in the video has to put in over what kind of terrain. I’ve been driving EVs for over 10 years and you learn pretty quickly you don’t get something for nothing.

Yes. I am answering without having gone beyond the quoted question, based on the First (and Second) Law(s) of Thermodynamics.

Yes, the idea of regen braking for e-bikes is super silly. You would need a bike with a lot of mass to make it work otherwise you are just working so much harder to get very little extra power. Maybe figuring out a dynamo might help a little but in the end the idea of the regenerating bike is going to be a tough concept. Maybe down the road someone will figure out something but right now it is just a idea born in the clouds.

I think this sounds like another "Perpetual Motion" scam.

Thanks, these are the things I suspected. It just doesn't make sense. It's weird, though, because the people in the video don't look like crackpots. Maybe that woman is the only customer so far, and it's somehow easy to convince her that the bike is boosting her efforts.

I'm thinking that a bike+rider is very light and can't make much kinetic energy for regen braking.

Hmm, maybe it gives a tiny boost upon pulling away from a stop and the rider convinces herself that the boost is still going? I doubt it but maybe.

And as Grumpus says, the generator is running on the flat. So it's like a dynamo hub except maybe it's taking more than 10 watts of kinetic power which is what I think those things usually suck from the rider. I ride a bike with one of those, and I run it day and night. I don't feel the drag although I know it adds up to something. But maybe their generator is greedier. OK that's a system that could work, but it doesn't sound like a lot of fun to ride. You have to pedal really hard to charge the capacitor. And then later you get a boost from the system, but how strong and for how long?

Nope, it doesn't make sense to me. But I could be wrong.

Explain to the cops you were merely charging your battery.

eh.... self charging?
regenerative braking isn't exactly new.
capacitors aren't exactly new.

You could do the exact same thing with a lithium batter bike (car/plane)

Everything in this video is exaggerated.
Most of the energy expended while cycling is wind resistance. Energy lost to braking is minimal in comparison.

The only interesting part is the capacitors.
Even so, I see no technical breakthrough on energy density.

Granted, as soon as true "super" capacitors are developed and released publicly, all fossil fuel technologies and chemical battery technologies become obsolete over night.

I look forward to that day.

Did he look like this?


https://cimg3.ibsrv.net/gimg/bikefor...349f08beba.png

I think before we all poo-poo the idea based on preconceived notions of motors, generative power, supercapacitor capacity, and primarily the style of rider this is geared towards, we should see all the facts. I mentioned in an earlier post that I would like to see the w/hr output of the supercapacitor pack. I'd also like to see the controller to determine when and how much assist is delivered under various conditions.
I, for one, would rather see an e-bike that rides much like a regular bike on the flats or downhill, and gives assist only on hills or high demand situations than some kid tooling along at 35mph on his throttled e-bike.
But that's just me. ;)

I’m not sure what you are looking for in a “true” super capacitor but it would still be a chemical battery. That’s all that super capacitors are. They use electrodes and electrolytes to store energy in a chemical form. They just happen to be able to be charged and discharged more quickly than other batteries. There is nothing magic about them.

As to regenerative charging, yes, it had been around for a very long time. It is a bit of a flim flam, however. It can take some of the momentum of the vehicle and convert it into stored energy but not all of it. It also only gives back a portion of the energy as useable power. But the First Law of Thermodynamics says that the change in energy is equal to the heat added to the system minus the work done by the system. In less technical terms, if you put a certain amount of heat…in this case…electrons into the system, you can’t get back that same amount of electrons because some of the inputted energy is lost to work. In the case of regenerative braking, you will not gain back all the momentum of the vehicle as electrical energy because some of it is lost through the work of stopping the bike. There is no free lunch.

As others have pointed out, a bicycle is pretty small and light. There’s not a lot of energy to get back and you are losing a fair amount of that energy. The supercapacitor also has its inefficiencies…both going in and coming out. The mechanism for regenerative braking would also add losses to the bike in both complexity and weight.

No. This was a real person. And his invention was being looked at by the federal government and many others. He even made national news. But never was able to produce a working machine. Late seventies IIRC. Possibly early eighties.

https://www.upi.com/Archives/1984/02...5513446619600/

It's called "actors." I hear there are few of those in your city?

To make it work, I think you'd need a series of buildings with (free) elevators and long ramps. Ride up to the top, coast down and charge whatever power storage device you have, and ride to the next skyscraper. It'd be interesting to see, a cross between Rube Goldberg and Marble Works.

Observation here. My hybrid Prius loses a lot less miles per gallon going over the West Hills of Portland vs taking a much flatter route that one would expect. Drive in town for example. 100-150' altitude loss. Ideal flat route I could push 50 mpg. I can get nearly that driving up close to 500', cresting and immediately going down. (There is randomness in that the battery starts with the charge it had after its last drive.)

So, yes, I could see real gains in overall battery performance and power used but the uphills get harder. More weight. Downhill that weights helps charge and maybe ups speed a little but small gains in speed when going fast make almost no difference in arrival time and often, max speed is dictated by corners, speed limits, kids ... Trade-offs. (Rats. I want that free lunch.)