The Lemon Fool

The brainchild of French entrepreneur Adrien Lelièvre, the Pi-Pop e-bike uses a supercapacitor to store energy rather than rely on batteries.

If riding a bike on a daily basis is too much of a challenge for you, you might be tempted to opt for an e-bike.

The issue with those is that the production of the batteries consumes a lot of natural resources such as lithium or rare-earth elements which require extensive and often environmentally impactful mining procedures.

French entrepreneur Adrien Lelièvre, however, has engineered a pioneering, sustainable solution.


It goes on to say

“The system gets charged when the ride is easy and when the bike brakes - thanks to engine braking - the energy is given back when needed,”

Surely its going to be a bit like riding a bike with one of the old style dynamos on the front?

https://www.euronews.com/next/2023/09/2 ... -a-battery

Let me get this straight. You don't get a single calorie of energy back from this machine that you haven't put in yourself? It sounds a bit like lending money to yourself.

The reviews are astounding, not least because I can't find any that aren't basically just a rewrite of the manufacturer's blurb. This is one of the more extensive reviews (https://bgr.com/tech/pi-pop-is-the-firs ... a-battery/), which somehow doesn't manage to say that the reviewer has ever ridden it.

This one (https://www.aroged.com/2023/05/31/we-ro ... es-itself/) does say that the reviewer has ridden it, but then says it was only for a few hundred meters, and it was brilliant because there was no violent engine braking. (Hey,you learn something new every day.) And that the reviewer is looking forward to riding a bit more when he/she gets the chance.

This review (https://www.velogalaxie.com/en/nouveaut ... dit-pipop/) says nothing whatsoever about the bike except that it doesn't produce noxious gases. And that the batteries supercapacitors ought to last 15 years, which is better than lithium batteries, which according to Euronews (https://www.euronews.com/next/2023/09/2 ... -a-battery) aren't destined to last more than five or six years. (Oh really?)

So where can you ride this lean, green machine to the best advantage? In towns where all the roads go downhill, of course. The reviewers' wisdom is that it's a bit of a bugger to ride on the flat because you have to pedal much harder than usual to put any charge into the device. But you'll be glad when you get to an upward incline. Oh yes you will.

Call me a wimp, but I think my first e-bike will be capable of importing energy that somebody other than me has generated. In the meantime, I've got this great idea for harnessing surplus kinetic energy with a revolutionary type of elastic band. Elizabeth Holmes says it's going to be worth a squillion dollars some day.

BJ

The reviewers' wisdom is that it's a bit of a bugger to ride on the flat because you have to pedal much harder than usual to put any charge into the device.

...which reminded me of the old fashioned dynamo lighting. Eventually you got so knackered riding your bike, the light only lit up on a downward pedal push - perhaps it was the fore runner of the flashing pushbike lights which seem to be all the rage these days.

Tedx wrote:...which reminded me of the old fashioned dynamo lighting. Eventually you got so knackered riding your bike, the light only lit up on a downward pedal push - perhaps it was the fore runner of the flashing pushbike lights which seem to be all the rage these days.

Oh yeah, and then you got so deadlyknackered that you lost the will to live and disengaged the charge wheel, and opted to take your chances in the dark without any lights at all.

That wasn't quite so suicidal as it sounds, because you knew that anybody within a half mile radius could hear you coming. zzzzzzzz, yeeeeeeeeeee, YEEEEEEEEEEE, whizzle whizzle YEEEEEEEEEEE! And all the while, the damn thing was eating away steadily at the rubber on your tyre's sidewall. Which would inevitably end in tears, curses and probably a loud bang.

BJ

....ah fond memories

bungeejumper wrote:Let me get this straight. You don't get a single calorie of energy back from this machine that you haven't put in yourself? It sounds a bit like lending money to yourself.

BJ

In fact, lending money to yourself, and charging ( ) interest on the loan

--kiloran

So what's the difference between a "supercapacitor" and a rechargeable battery?

In principle, if you can capture energy in braking and on the downhill, it should be a Good Thing (supplementing, not replacing, conventional recharging). The principle has been around a long time: I first heard about it in the context of gyroscopic storage for motor vehicles such as milk floats and Swiss buses, right back in my 1970s schooldays.

If the opportunity comes my way, I'd happily take one out for a test ride!

UncleEbenezer wrote:So what's the difference between a "supercapacitor" and a rechargeable battery?

Storing the energy via electrostatic charge rather than chemically.

As a circuit component the lines get a bit blurrier - they have very similar equivalent circuits schematically but with the parameters in different places (lower internal resistance, different time constants etc)
An analogue might be a super cap' is like RAM whereas an LiFePO4 cell like an SSD

bungeejumper wrote:Let me get this straight. You don't get a single calorie of energy back from this machine that you haven't put in yourself? It sounds a bit like lending money to yourself.

That's true of any bike car, or other form of transport which doesn't feed you while you travel!

This bike does save you energy (you useless than on a standard bike, theoretically) because it captures energy that you would otherwise have wasted on the brakes. Also, allows your muscle to work closer to optimum level presumably. Sounds like the benefits would be relatively marginal though... are there any detailed calculations/measurements published by the inventor?


GS

GoSeigen wrote:

bungeejumper wrote:Let me get this straight. You don't get a single calorie of energy back from this machine that you haven't put in yourself? It sounds a bit like lending money to yourself.

That's true of any bike car, or other form of transport which doesn't feed you while you travel!

This bike does save you energy (you useless than on a standard bike, theoretically) because it captures energy that you would otherwise have wasted on the brakes. Also, allows your muscle to work closer to optimum level presumably. Sounds like the benefits would be relatively marginal though... are there any detailed calculations/measurements published by the inventor?


GS

The actual idea is pretty sound especially if you think of the amount of energy one normally has to take out a bike via the brakes on a descent.

It's a truism of cycling that as long as you're going back to where you set off the net climb is zero - but it never feels like that
- in principle this should make that apparent discrepancy a bit less obvious

Practially it's all going to come down to the weight and rolling resistance it adds to the bike; the link says the bike is 20kg which is on the heavy side
- for comparison my e-commuter is nearer 24 (and at level 2 or 100% assist it does feel strangely like riding a lighter, but meaty bike - it goes up to 300% where it's an armchair )

- sd

GoSeigen wrote:This bike does save you energy (you useless than on a standard bike, theoretically) because it captures energy that you would otherwise have wasted on the brakes. Also, allows your muscle to work closer to optimum level presumably. Sounds like the benefits would be relatively marginal though... are there any detailed calculations/measurements published by the inventor?

Fair points, of course. If a machine can help you optimise your output by borrowing energy when you've got an excess of it and then paying it back when you need a bit extra, then that will make your task easier.

But if there are any detailed calcs, I can't find them. Although one of the reviews does burble vaguely about how the capacitors can store enough power to lift 50 metres of vertical height. (What does that mean, BTW? That it'll get the bike and rider to the top of a 50 metre hill, or just the bike, or just the gear itself? Or something else? This total non-physicist numpty would like to know.)

The stranger thing is that this bike has been in production for about two years, at a current rate of about fifty machines a month, and as far as I can see, nobody anywhere in the world seems to have done a systematic road test and trial, or to have reported on their medium-term experience. As my psychotherapist wife would say: "I know what that that says to me. What does it say to you?"

Go on then, Fools, your challenge for today is to prove me wrong.

BJ

A garden shed Brit effort...:

https://youtu.be/V_f8Q2_Q_J0?si=CUfhABXFLah9jDQz

bungeejumper wrote:But if there are any detailed calcs, I can't find them. Although one of the reviews does burble vaguely about how the capacitors can store enough power to lift 50 metres of vertical height. (What does that mean, BTW? That it'll get the bike and rider to the top of a 50 metre hill, or just the bike, or just the gear itself? Or something else? This total non-physicist numpty would like to know.)

That's actually quite a useful figure to know. I'd assume it means enough energy to raise bike plus average rider (100kg total?) by 50 meters thus giving them 50 meters of potential energy. I'd also assume this would be without any assistance from the rider; similarly if the rider were contributing 50% of the effort throughout the assistance would be enough to surmount 100m of altitude.


Based on those assumptions and figures, for the sort of riding you'd do through hilly parts of England it might be a nice experience, a bit more work on the flat/downhill but easy ascents.

It would be much less help for the sort of riding I used to do in Japan where the ascents were a continuous 1000m or so with similar descents. But then I sought out those hills for the exercise and wouldn't have wanted the help anyway.

Who knows how I'll feel when I'm past retirement age? I might get the urge to go back to Japan and re-live my feckless youth, powered by a French supercapacitor? Hmm... more likely to sit outside a French cafe with a glass of wine or plateful of crêpes methinks...


GS

Worth adding that those capacitors are incredibly dangerous, even the garden shed version could probably kill you if you touched the wrong bits, so safety is a big issue.

GS

UncleEbenezer wrote:So what's the difference between a "supercapacitor" and a rechargeable battery?

The cost, I'd predict...

GoSeigen wrote:That's actually quite a useful figure to know. I'd assume it means enough energy to raise bike plus average rider (100kg total?) by 50 meters thus giving them 50 meters of potential energy. I'd also assume this would be without any assistance from the rider; similarly if the rider were contributing 50% of the effort throughout the assistance would be enough to surmount 100m of altitude.

Based on those assumptions and figures, for the sort of riding you'd do through hilly parts of England it might be a nice experience, a bit more work on the flat/downhill but easy ascents.

LOL, that's quite a lot of assumptions! I guess the real substantive question would be how much power those capacitors could store, and how long they'd last you. Toyota's brake recovery systems have the benefit of being able to store their power into a bettery, whereas this one doesn't.

Hmmm, TedX's video (https://youtu.be/V_f8Q2_Q_J0?si=CUfhABXFLah9jDQz) does have some relevant comparisons, mostly in the last couple of minutes. The home-made racing bike conversion (with home-wound electric motor windings and everything) was emptied of power, then freewheeled down a fifty-metre slope, and then turned round for the return journey, of which it managed about 40% under its own steam. That's a decent contribution, I suppose? But personally I'd be in the cafe with you, perusing the menu and wishing I'd spent another grand on something that I could plug into the socket on the wall. In this rural area I have about half a dozen retired neighbours who ride for 20 or 30 miles every afternoon on the last decade's technology. They have no complaints.

BJ

Cant you just ride a normal bike, get fitter, then you dont have to worry about uphill gradients. The more you ride the better you tend to get.

Gerry557 wrote:Cant you just ride a normal bike, get fitter, then you dont have to worry about uphill gradients. The more you ride the better you tend to get.

You could. See you in thirty years' time.

BJ

bungeejumper wrote:

Gerry557 wrote:Cant you just ride a normal bike, get fitter, then you dont have to worry about uphill gradients. The more you ride the better you tend to get.

You could. See you in thirty years' time.

BJ

It's great in theory...
but my commute is downhill on the way to work (150m over 18km)
and often 20+ degrees warmer on the way back

So I see the assistance as an earned benefit

GoSeigen wrote:Worth adding that those capacitors are incredibly dangerous, even the garden shed version could probably kill you if you touched the wrong bits, so safety is a big issue.

While it's true that, as the old saying goes, it's mills that kills and volts that jolts (mills = milliamperes, i.e. current), and it's generally reckoned that 100mA is lethal, with as little as 10mA being able to cause muscle contractions, these 400F capacitors are just 2.7V each.

So, with the guy having wired eight in series the bank will be charged to only 21.6V, and while the effective 50F of the bank will store a lot of coulombs, the "mills" that flow out of it will depend on body resistance and it's extremely unlikely that you'll get even a mild shock from the 21.6V ... unless you connected one side to, say, the inside of your mouth and the other side to another soft and moist part of your anatomy.

For someone who was into electronics in his yoof, when 400 micro Farad electrolytics were considered big, these supercapacitors are kinda gob smacking ... indeed, I remember our physics teacher at school (quite a few decades ago now!) telling us that a one farad capacitor would have to be the size of a house ... although maybe he was talking about Leyden jars ....