Originally Posted by cyccommute (Post 23478660)

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.

Originally Posted by Iride01 (Post 23478661)

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/

Originally Posted by Iride01 (Post 23478661)

But never was able to produce a working machine.

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

Originally Posted by CrimsonEclipse (Post 23478788)

A capacitor is most certainly NOT a chemical battery.
They are NOT the same. Not even close.
Capacitors use electrostatic charge, not a chemical change.
and their present energy density is an order of magnitude less than chemical batteries.
Thus, not ready to replace LIon and lead acid.

Originally Posted by wheelreason (Post 23478918)

I was (surprisingly) having a discusson with someone who should know better about something similar, it started funny, got heated, and I finally said, "yeah, if you start at the top of Pikes peak, and only ride one way all the time, maybe"....

Originally Posted by cyccommute (Post 23479034)

Super capacitors aren’t the same as a capacitor. They don’t use an electrostatic charge to store energy. They use solvated electrons in a media and electrodes. They are like both a solid state capacitor and a battery. And, no, they can’t replace chemical batteries because they can’t hold nearly enough charge.

Originally Posted by CrimsonEclipse (Post 23479225)

huh, I learned something today.
Always assumed that super capacitors were a generic marketing terminology.

And ooooh boy, was that a rabbit hole I didn't expect to go down today.

Originally Posted by squirtdad (Post 23479234)

Pretty sure that in physics, just like accounting TANSTAAFL applies (There aint no such thing as a free lunch)

Originally Posted by Bald Paul (Post 23478609)

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. ;)

Originally Posted by cyccommute (Post 23479034)

Super capacitors aren’t the same as a capacitor. They don’t use an electrostatic charge to store energy. They use solvated electrons in a media and electrodes. They are like both a solid state capacitor and a battery. And, no, they can’t replace chemical batteries because they can’t hold nearly enough charge.

Originally Posted by choddo (Post 23479275)

I’d like to pick you up on the “adding heat to the system (as electrons)” - ain’t no one creating any electrons in this here scenario :D
and you’re introducing energy, not heat. Heat is the last thing you want.

Originally Posted by choddo (Post 23479273)

Kids can’t ride throttled ebikes here, they are treated like mopeds with license required etc,

Originally Posted by grumpus (Post 23479069)

Some things that seem simple and obvious to some people are clearly less so to others; ideally we occupy ourselves with things we are good at and leave other stuff for other people to sort out. Sometimes however someone thinks he has a brilliant idea that nobody has thought of before, like airless tyres or hubless wheels or self-charging e-bikes ...

Originally Posted by noglider (Post 23479473)

Am I correct in noticing that these bad ideas have a stronger tendency to come back repeatedly in the bicycle industry?

Originally Posted by noglider (Post 23479473)

One strong example is the one pedaled with levers instead of spinning cranks. Back in about 1980, I attended a bike trade show, and some Japanese folks were displaying this proudly. They invited me to try it with a bicycle on a stand. I pedaled really hard, and the thing fell apart, and I fell down. I was not hurt, and they were very embarrassed. I told them why their idea was fatally flawed, and they thanked me. The flaw isn't that it fell apart, it's that with levers, there is energy required to decelerate the cranks with each cycle.

Originally Posted by john m flores (Post 23479583)

While this bike certainly won't break the laws of thermodynamics, could it possibly make biking more enjoyable and achievable for people whose route include some challenging hills? These bikes could charge the capacitors on downhills and also a little bit on flats (situations that don't place riders at their physical limits) and then use that charge to help "flatten" those hills. It's no panacea, but I could see that being useful for certain folks and certain riding conditions.

Originally Posted by noglider (Post 23479588)

Yes, it's occurred to me that maybe it could do that. They would have to keep the weight down, and that limits the amount of charging and powering that is possible. So maybe?

Originally Posted by john m flores (Post 23479583)

While this bike certainly won't break the laws of thermodynamics, could it possibly make biking more enjoyable and achievable for people whose route include some challenging hills? These bikes could charge the capacitors on downhills and also a little bit on flats (situations that don't place riders at their physical limits) and then use that charge to help "flatten" those hills. It's no panacea, but I could see that being useful for certain folks and certain riding conditions.

Originally Posted by cyccommute (Post 23479363)

Regenerative braking is just using a generator to provide the braking force for some or all of the braking. Generators generate electrons (or really move electrons) from interaction of electric fields. The generator is run backwards which produces the electrons that provide the energy to whatever storage system is being used. The reason I said “as electrons” is that the laws of thermodynamics were developed when electricity wasn’t a thing. They still apply to electrical generation, however, including the limitations of those thermodynamic laws. That includes the efficiency of the system which is limited to about 30%. About 70% of the energy available is lost and can’t really be captured. That’s the real reason that regenerative braking is a bit of a flimflam. Most of that energy created by harvesting the kinetic energy is lost to the universe and doesn’t end up in whatever storage system is being used.

And, yes, there is heat involved. Run a generator in either direction and there is heat generated just due to the action of the electric fields. Heat management is a problem in all mechanisms.

Originally Posted by choddo (Post 23479794)

Indeed. The last two paras basically being the same phenomenon.

But I thought it important to be clear that we don’t add heat to store energy. Adding heat is an undesirable by-product that actually loses us useful energy. And we don’t create electrons when we charge things. We just move them.

Originally Posted by cyccommute (Post 23480239)

Heat is energy. Just as we don't create electrons, we don't "create" heat. We don't create anything with regards to any of the forms of energy we use. We just move it around. We can use the names interchangeably. My point on the "heat" in the form of electrons is that the regenerative braking system uses energy to make work to make electricity and a bucket load of "waste" heat.

The video claims that the bike doesn't need to be charged but they only tangentially mention that the recapture of braking energy is limited. It's especially limited in their example because they don't use the energy captured from front braking at all. And, as most bicyclists should know, the vast majority of braking power on a bicycle comes from the front wheel. They are capturing a fraction of a fraction of the fraction of energy they have available. More hype than substance and it most certainly won't provide as much boost as a battery powered electric bike will.

Originally Posted by choddo (Post 23480242)

Ok well in my physics degree and generally in British English we never use the terms heat and energy interchangeably so the phrase “we add heat in the form of electrons” (paraphrasing) made no sense to me. Agree with you there’s some waste heat from the regen system but obviously a lot less than a traditional brake.

Originally Posted by etherhuffer (Post 23480478)

Any Mazda drivers here? I have a 2016 Mazda 6 with the 'technology package' that utilizes a big capacitor to increase mileage. It supposedly adds about 1mpg to your fuel economy. I think the idea is the charge is used on acceleration instead of the alternator and thereby reduces drag in the system. Not sure but that is how it was explained to me. But here is the rub. In order to gather/hold/expend that energy as it cycles through this device, you need a special battery, and it's 450 bucks, Mazda only. Some Aussies claim you can use glass matt battery instead, but of course at the risk of an expensive problem to the car. So I penciled out 1 mpg over the 5 years or so of batter life, and then figured some fuel costs. The math says the cost of the special battery negates the fuel savings IN DOLLARS. So you are not really getting an economic benefit from the 'technology package" but I guess the planet is saved some exhaust gasses. The laws of physics vs the laws of economic behavior are not always aligned, considering that if you buy the car new, you pay up front. If you bought the car used and depreciated, then the extra technology might be more palatable. Until the Law of Dealer Repairs rears its ugly head on a dealer only high tech item!

This is calle i-ELoop on Mazda site.