This has to be a parody account right?
Either that, or he’s not very smart, had a thought, poppet it into ChatGPT, and ChatGPT as it tends to do, affirmed his dumb idea, and he ended up asking it to make a Linkedin post for him on the idea.
I’ve seen similar stuff from students who think they’ve cracked how something works, only to be incredibly wrong, because they only know half of what they need to, but don’t know enough to understand how little they know. It’s part of the journey of getting sorta-good at something though.
A parody account… on LinkedIn?
I’m becoming increasingly more and more confused as to what this site’s purpose is intended for… I think they lied to me in college lol
So you’re on your ebike, going 15mph. Using 140w or so. You’re spending 15-20w on the drivetrain, and the remainder is entirely aerodynamic drag. You’re putting 120-125w into making wind move. You’re also losing 5-10 watts to the drive electronics and dashboard. So your total power use is 150w.
If you’re going to recharge a battery. In the same time it takes to ride, you need to get at least 150w of power into another battery. Sadly, batteries don’t actually “just cleanly charge” there are some losses, but since we’re going to take an hour to charge it, lets call it 5%. So to fill up that battery we need 157watts of input power.
Your bike, moving at a steady speed, is absorbing 150w of power. If we want another 155w of power, where is that going to come from? If we take it from… say… the front wheel, we are now absorbing another 155w of power. So to maintain the same speed, we now need to push the bike along with 305w of power. And… now we need a bike that makes 305w of power, to go the same speed we were going with 150w. … And we’re only generating 155w.
There is no free lunch. If you’re doing work, you need to get that power from somewhere.
Counterpoint:
Hills exist, go down them.
Like, the whole point of these things, at lesst as I see them, is that you get that free lunch on the way down a hill, then when going up a hill, well yeah, you still aren’t gonna like, be 1:1 be able to power right back up it, but it will be easier going up that hill than if you did not have your free energy lunch on the way down.
This then results in you not needing to expend as many literal calories going up a hill, so now, you don’t need as much food to recharge after a ride, thus you do actually on net come away with at least a portion of a ‘free lunch’, in that you don’t need as much food.
But yes, I will give you that… the overall weight added to the bike from the batteries would have to be in a manageable range, so that the uphill assistance is not just entirely used on uh, pulling its own weight.
You do get about 5-10% more range with regen on an ebike, the downside is it needs to be a hub motor which sucks at climbing hills, and one with no internal clutch which means pedaling with the motor off wastes a ton of energy.
The problem with “go down a hill” is that the LinkedIn idiot wants to use the power of one motor to generate power in the other. Regenerative braking only needs one motor and it acts as a generator when braking.
I mean… you can do regenerative breaking in a hyrbid car, where the main LiON battery is also charged from the ICE engine.
I had a hybrid Prius C that worked this way.
Roll it down a hill, far enough, in the right mode?
Recharges the main hybrid battery.
And then, you can also put it into a low power, EV only drive mode. Can’t do inclines or go fast, but you can get up to about 20mph on flat terrain.
Like, I’ve done that at least once, as a kind of makeshift jumpstart sort of thing.
Presumably, it may be possible to scale such a system down to a bicycle, or maybe moped or motorcycle.
And the LinkedIn guy specifies that there are two different batteries, which are capable of transfering power between each other.
So their system is regen braking -> bat 2 -> transfer -> bat 1 -> drive motor.
Personally, I don’t even see why you need two distinct batteries, just have a powerstation type thing with a some software that regulates power uptake and output intelligently.
Regenerative braking is not the problem. Thats been solved. The LinkedIn user is trying to invent perpetual motion
They’re not actually describing that, explicitly.
What he’s said can be interpreted that way, if you add some words he didn’t say into this post…
… but he didn’t actually say that.
A ‘continuous self charging loop’ is not the same thing as… that, but which also generates infinite energy or is somehow overunity, over 100% efficient.
That just means there is a continuous loop by which energy can flow from the regen braking to the motor.
It doesn’t mean that energy is always flowing through that loop… it just means that some amount of energy could be.
It doesn’t mean that power coming into the motor or batteries always exceeds the maximum power consumed by the motor.
(that would infact be very bad and cause the batteries to explode/burst into flame at some point if we’re talking about LiON)
Continuous loop is… an actual electrical engineering term, and its actual meaning is basically as I have just described.
Now sure, if this actual LinkedIn post is rather recent, well its rather cute that he seems to think he is the first person to come up with this idea…
But, it is also cute that the vast majority of commenters in this thread are suggestible (by way of being mentally framed with a narrative by the comm this is posted in and the post title) and have either poor reading comprehension, or just didn’t bother to actually read what this ‘lunatic’ wrote… and are acting like they’re better engineers than this guy, that he’s bonkers… when in actuality, they’re all showing their own asses unintentionally, proving that they don’t know basic electrical engineering terms.
For this guy to have actually been trying to describe a perpetual energy devicre, he would have had to say something like ‘a continuous- ly self charging loop that is over 100% efficient’.
He even specifically said his goal was to reduce the need for external charging.
Not eliminate, which would imply he thought it was overunity, but no, just reduce, which… would indeed be the result if his system worked and granted an extra 10% or 20% to overall EV bicycle range.
Yeah, in engineering, as well as language, precision and small details can make for large differences in the end result.
Seems like satire to me. Pretty funny too.
The Law of LinkedIn:
If you think it’s satire, it’s probably actually just a really stupid individual.
Do most e-bikes not charge from the pedals? Combine that with regenerative coasting/braking, and this isn’t really that dumb. Like yeah, obviously thermodynamics, but an E-bike with pedal charging isn’t a closed system.
Regenerative braking is not worth it on bikes… it’s worth it on cars because you are slowing down over one and a half tons of weight and going much faster so there is serious amount of energy to be recovered
You’d basically need electronic braking for this to work. Which should be theoretically possible since we already have electronic gear shifts. Would be tricky to get the feel right in the transition between motor to friction.
The pedals seemed like the bigger contributor, I just added the other for a few percent.
If I’m riding an electric bike, it’s to make pedaling easier. Why would I want an electric bike that’s harder to pedal?
If you extract enough energy from pedaling to charge a battery while also travelling, you’ll definitely end up using more power than less. Which absolutely defeats the purpose.
All these “smart” ideas would already be implemented if they were actually clever and deployable. The reason no one does it is because physics doesn’t work that way.
I’ve built two eBikes and can confirm that they do not.
Unironically, I would enjoy a bike that I could pedal at a constant speed, charging the battery all the while. Give me a display that indicates my pedaling speed so that I can tailor my exercise and you’ve created a moving stationary bike. I hate having to stop at lights and whatnot, so a rotation-based stabilizer would be nice at speeds below 10 km/h as I pedal the equivalent of 30.
Really, it’s just unfortunate that the engineering doesn’t work out for momentum->chemical energy unless you’re biking at a professional level and willing to cruise slowly or charging the battery at home. Bleh
Yeah, same, I like this idea.
If your actually mobile bike can also be used as a makeshift generator, to feed into a home backup battery?
Yeah maybe not huge levels of appeal there, but it is a neat utility feature.
Maybe I’ve played too many zombie survival games with base building… or, maybe I am aware of the shockingly shitty state of the US power grid.
Also:
If you have a bike, and battery/powerstation like that?
That leads to a potentially amazingly ironic situation where you effectively jump start a dead ICE car ultimately from a fucking bicycle, if you can hook your battery/transformer/power station thing to charge a portable car battery jump starter.
Honestly this would make a great video idea for Tom Stanton.
I love it, and it reminds me of James May talking about using launch control at a zebra crossing
I don’t claim to be an engineering student, why is this a bad idea? Wouldn’t he just put a “collector” of energy (like a wind turbine) on the wheels?
It’s a bad idea because he’s essentially talking about a perpetual motion machine.
That makes sense, except the collection of the energy can be less than the energy expended, like an automobile or wind turbine. Then it could be a perpetual machine.
It would be like this:
Energy in => convert to a gear that makes it way more energy => store energy, repeat.
I must be missing something.
Gearing doesn’t make more energy output than the energy put in.
convert to a gear that makes it way more energy
nah, see, a gear is basically just a fancy pully. it can make it easier to pedal up a hill, but only by making you have to pedal many more times to do so. each turn of the crank arms takes less force, but you have to do it many more times. it isn’t actually reducing the energy requirement, and it isn’t multiplying your energy input.
what you’re describing here would be some kind of magic.
except the collection of the energy can be less than the energy expended
The collection will always be less than the energy it takes to generate it. There no magical gear or trick to change that.
Maybe you can join his team!
But I can forgive a non engineering student… its impossible.
It would wash out. Any energy collected would be at the cost of resistance. So add fans to add wind resistance. You could collect energy from coasting and braking, but that’s just tech we’ve been using for years in cars, and it comes at the cost of movement. It actively slows you down because the energy has to come from somewhere. And since energy conversion is hardly one-to-one (loss to heat, etc), storing it into a battery and then pulling it out again means you won’t gain as much as you lose.
Energy cannot be created or destroyed. If you are generating energy, you’re taking it from somewhere, and on a bike, it’s from your forward movement.
Okay, I get that, but wouldn’t the collection be a separate system? The energy is being created by the battery, then a separate system collects the energy.
Imagine it like this, you have two glasses of water, labeled “speed” and “chemical.” You can only transfer water between glasses. And messily. It’s a sum of water, a specific weight of water between the two glasses that you own. In placing the water elsewhere, you haven’t done much besides lose a portion in the transfer. You can absolutely do what you’ve said! It will, unfortunately, just be a transfer from the speed to the chemical glass. You’d just lose a bit in the transfer.
Because its all the same energy, and the contraption just slows down.
But if you’re on a hill, you’ll go much faster, thus storing more energy.
Now you’re introducing potential energy (a hill), which will be used up (or rather be fully converted to kinetic energy) once you reach the bottom, and you’re going to need the same or more energy to go up that same hill again (depending if you take resistance into account).
We already have tech for capturing kinetic energy for later in the same battery used for driving called “Regenerative braking” (cuz’ the motor is used as a generator in place of brakes, and you’ll need to drive said generator by capturing/braking some of your kinetic energy/forward motion).
EDIT: In other words: You could just start on a really high hill and you’d be able to use the weight of the bike and yourself as a “battery”, never needing any actual battery/motors/wiring/etc.
Yes, you could collect energy while coasting down a hill, but it would slow you down. Which is fine if you want to slow down; this is the basis for regenerative braking. You might be thinking that a pinwheel spins like crazy in the wind, and that’s just free energy. But a pinwheel doesn’t store anything. To store energy, you need to add resistance, and the more you add, the more energy you collect and the harder it is to spin the wheel.
So at the end of the day, you’ve got a fan at the front of the bike that is either spinning quickly with little resistance and storing little energy or one that is spinning slowly and collecting more. And the slower it spins, the more pushback there is against your forward movement.
Despite there being two batteries, this is still a single system which uses energy to propel the bike forward and collects energy by preventing the bike from moving forward. They offset. The only way to have the energy to propel the bike is by introducing energy from another source (not related to the movement of the bike) such as a battery charged ahead of time or calorie loss of the rider (active pedaling).
Thank you for this detailed explanation. I appreciate it. That’s exactly what I was thinking about, a pinwheel.
It could be an OK idea that just wasn’t explained right. Maybe he just wants regen braking but with one wheel for charging and the other wheel + separate battery for power at any given time. Energy would come from pedalling and hills. None of that was explained though
What happens to an object in motion when you collect its kinetic energy?
Okay, I admittedly know nothing about this, so bear with my ignorance. Aren’t you just moving gears? It would generally be like an auto engine where you have all of these explosions that push gears. You’re just moving the gear in one direction as a click, click, click.
Conservation of energy, basically it’s not that it wouldn’t work “at all” or appear to anyway but that it wouldn’t work as desired. You can’t recapture the power used to propel the bike because it’s being used to propel the bike. Adding a collector increases the power needed to turn the wheels and basically makes the drive battery’s job harder, so it runs less efficiently and runs out faster, battery 2 does charge and can be run from, but in the end you end up with less range due to the stacking inefficiency and energy leakage. The closest functional system to what they are talking about would be a breaking system like electric cars use.
Thank you for taking the time and patience, this explains it for me in a way that makes sense.
Turn off the engine of your car, does it keep rolling at the same speed forever?
Where are you going to get that power on a bike? Your legs. Do you really want to peddle away to charge a battery at SIGNIFICANTLY reduced efficiency, then with even more loss of efficiency discharge the battery into an electric motor? Or do you just want your energy going directly to the wheels?
The person in the post is trying to come up with an infinite source of energy which is not possible.
All of these points are well taken, but I didn’t understand it as infinite, but more like to get you where you’re going.
On an e-bike you would be losing significant portion of energy from propelling the bike, friction, air drag and heat loss. You might be able to put a small amount of energy back in from pedaling, going down hills or even braking, but certainly not enough to make it perpetual.
Perpetual motion machine are physically impossible based on our current understanding of physics. Many, many people have attempted to create them, but they all fail from the reaaons above.
So last question, I promise.
A wind turbine collects the energy of the wind through movement. A gear can give more “force,” so I’m assuming more movement of something. If you have 2 different systems, one that collects the movement, or more “force,” and one that is making the bike move, why wouldn’t that be close to collecting as much as you put in. You’d have to charge occasionally, but not all of the time.
No, they are not separate systems and you will always have significant losses of energy to friction.
Gears change how energy is transferred, but more gears means more energy loss. Always.
With the bike, the battery (and pedaling) is the source of your net energy output. Losses from friction to the ground and air drag will be the most significant net consumers of the energy. It doesn’t matter how the rest of that energy is moved around within the system(s) of the bike.
Ultimately, what determines the distance you travel is the capacity of the battery and what external environmental factors affect the bike and by how much. Biking at 3m/s will have less air drag than 10m/s. Friction will be affected by the surfaces you go over, with something like mud taking more energy compared to something smooth like smooth concrete.
If you are drawing energy out of a system them that amount of energy is removed from the system. A freespinning gear won’t generate electricity. It has to be pushed, which requires more energy from the power source, and is always a net loss because of friction.
That is before the added weight of the additional batteries.
So trying to get energy back from a moving cycle will result in a less efficient bike.
Alternators exist on a car, why not on a bike?
You can power lights or a phone charger with a dynamo connected to the wheel and minimally noticeable drag/resistance. You can recharge a drivetrain with regenerative braking which requires high end motors to use the motor like a dynamo
Yes, you can collect some of the kinetic energy and put it back into a battery with regen braking, but most of the energy put into such a system will be lost to heat/friction, drag, drivetrain inefficiencies, battery inefficiencies, recovery inefficiencies, etc.
In the lunatic post, he’s not talking about regen braking. He’s talking about using the same system that moves the vehicle to simulatneously charge a battery. Which means you’re taking some of the energy which would normally move the vehicle and shunting it into a recharging “circuit” - which introduces even more losses.
The end result would be a machine that is less efficient.
Just assume a perfect world, and we won’t loose any energy!
… Though we won’t gain any either. -,-’
Regen braking is on every single electric car. But it’s incredibly inefficient and costs a lot of money to add it.
On a 60k car? Yeah it’s worth it. On an $500 ebike? No, not at all.
Oh shit you solved it!
I was being sarcasmic.
🥵
So we just need to put something on the bike to power the alternator…I know, an engine! Why has nobody thought of this before?!
Alternators don’t exist on electric cars. The closest is regenerative breaking, which powers the car by slowing the car down.
🤦♂️
It’s almost like, it regenerates its energy
Mechanical engineering student huh? Good to know he didn’t attend class on day 1 of dynamics
Mechanical engineering student huh?
1 week
This is a normal trajectory for college freshmen. Get introduced to a bunch of basic ideas. Spitball and try to see how you can apply them. Start running into all kinds of caveats and engineering hurdles. Go back to class. Bother the RA. Maybe actually learn more about what you’re trying to accomplish. Become a better engineer.
Knowing you can’t invent a perpetual motion machine is like high school level science, so being a first year college student isn’t an excuse.
Hearing that you can’t and understanding exactly why are two very different states of understanding.
One is simple recitation of a fact.
Yeah but you missed rule 1: Don’t post your gobshite ideas on LinkedIn.
Not believing you can create a perpetual motion machine should practically be an entry requirement. If you think you can you need to go back and do high school science again.
Nah, engineering students often forget and design perpetual motion machines. Usually, they remember why that is stupid and impossible before they post it publicly where I can haunt them forever.
It should be a graduation requirement. It really should be…
Physics’s older brother gonna be looking for this guy.
Someone has been spending too much time on ChatGPT.
Newton? Never heard of him.
A mechanical engineering student that doesn’t know the law of energy conservation?
I have a better one: charge from temperature gradients as it moves through new areas.
WOOOOOOOOOOOOOOOOOOOOOOOO!
Aw man, Lemmy finally got a LinkedInLunatics instance? How long has this been here? That was like the last thread I’ve been hanging onto with reddit. Finally, this place feels like a genuine alternative 🎉
The community (which isn’t an instance!) has been there for a couple of years already: https://sh.itjust.works/post/27701
If you haven’t come across it before there is the Lemmy Explorer tool (with options for Piefed and Mbin as well): https://lemmyverse.net/communities
Welcome to the fediverse’s LinkedInLunatics, my friend!
