Hello Scotty;
Do you think it is possible for the EV car manufacturers to employ a constant charging unit that could be connected to the drive train? it would work the same as the alternator does on a gas car. I'm sure there is somebody someplace who could do the math and figure it out. sure would be nice to be able to drive without the worry of where is the next charging station.
Hiker1
You mean a perpetual motion machine? 😆
a constant charging unit that could be connected to the drive train
They already do this. It's called regenerative braking.
Are you at all aware of the 2nd Law of Thermodynamics?
Lets be honest ... hardly anybody is. It doesn't exactly come up in day to day life. Unless you have a science background, or its your line of work, most people have blocked that high school lesson out of their heads.
Perhaps, but I'd hope most people would have absorbed enough to be suspicious of any idea involving perpetual motion even if they can't name the law of physics involved.
Well "most" could be wishful thinking. You may be shocked by how many people think heavier objects fall faster, and toilets flush the other way in the Southern Hemisphere.
... and I think you meant 1st law.
after a while those lessons tend to fade and blur together don't they 😉
They do blur, but really both the 1st and 2nd apply, as does the 3rd, they really need to be taken as a whole. :silly:
1. You can't win.
2. You can't break even.
3. You can't get out of the game.
Of course all the laws apply to everything. That's why they're laws. But they don't all illuminate any understanding of why something happens.
1. Most people can understand the fundamental concept that "Energy is conserved. It can neither be created or destroyed". Most of the time we can stop here.
2. I don't like this oversimplification. You can break even. In fact you must break even. You just can't get back to where you started. ("you" being a closed system, and the currency being energy which is what humans care about.). This deals with the abstract concept of entropy.
3. You cannot achieve absolute zero. True, but not particularly helpful here.
Well you have to take the energy to charge it from somewhere.
I assume you mean an EV with a gas engine that constantly charges it?
Those are called “Series Hybrids” or “Range Extended EVs” (REV) and there are plenty of these around.
The best known one is the BMW i3 EV’s range extender - it was a 600cc scooter engine used as a generator that would charge the battery if it ever gets low.
These are pretty much just more complex Gas cars. Instead of having a transmission to drive the wheels - you have to have a battery, a generator, an electric motor, and complex equipment to control all of that.
Most modern plug-in/full-hybrids (like the Toyota Prius, Kia Niro, …) and even most Mild-Hybrids (like countless euro-econoboxes) operate as REVs most of the time.
Well when speaking about EVs, that’s pretty much all non plug-in BEVs (hybrids).
Something like a Prius, Corolla Hybrid, Niro, Ioniq does not require any charging.
They do require filling up at a gas station every 450-650 miles to get the energy needed to charge the battery.
remove the motor and place a high-power alternator in its place
Where do you expect to get the power from? alternate the current from what?
You can't generate power from thin air, you need a generator - in the form of a fuel cell or an engine.
if you have a charging unit connected to the drive train
You can't get something for nothing. Generators aren't magic. They convert mechanical energy into electrical. If you use a generator to , lets say light up a 100 Watt light bulb, then that's how much energy it is removing from the mechanical system. In other words, it slows it down. And because perfect efficiency isn't possible, it's actually removing more like 150 Watts of mechanical energy. There are no free lunches in our universe I'm afraid.
If things worked how you describe, then you would have a limitless supply of energy and solve the worlds energy needs forever.
Thanks for the reply, It is almost what I was thinking if you remove the motor and place a high-power alternator in its place. that is what I am talking about. you could drive across the country without stopping to charge the battery. maybe someday it will happen.
It kinda already exists. The regenerative braking on the Prius, Tesla, and many other EV’s are basically high powered alternators.
But these are only efficient when NOT accelerating NOR maintain speed. They are only effective during deceleration, or going downhill.
@hiker1, let me explain - intuitively:
(Not from a Thermodynamics point of view - here's it explained with intuitive newtonian physics' principles, using Einstein's work but without going into it.)
Let's say you have a cake that weights 3 lbs, it would seem obvious that
"You can't have your cake and eat it", as in, "you cannot simultaneously retain your cake and eat it"
If you eat 1lbs of the cake: there will be 1lbs in your body, and the cake will have 2lbs left.
If you don't eat: there won't be any cake in your body, and the cake will have 3lbs left.
This is called "Conservation of mass" - and this is a concept we all intuitively are familiar with.
Now, mass and energy are interconnected
This was shown by Albert Einstein as: Energy = Mass * c^2 (c is a constant)
So the same way you can not get a cake from nothing, the same goes for energy.
Now that we are done with the basics,
When you're moving in a car at 75mph, Take your hand out of the window, and try to keep it in one spot:
What you'll find your self having to put in quite a bit of effort to maintain its position.
Another experiment you can do, is driving up to 75mph and shifting your car into neutral:
You'll find that due to the resistance with the ground and with the air, your car will slow down.
Sustaining a certain speed requires you to input energy, energy that is taken away from you by friction.
But here's an interesting question: let's say you're driving your car at 75mph on a flat road,
You're pushing the throttle a bit to maintain speed, what if you push it in a bit more?
You'll find that your car will accelerate.
So, we can all agree that, if you input more energy taken away by friction - you'll accelerate.
From those 3 facts we can understand that when you're cruising at a set speed:
You're inputing the exact amount of energy that gets taken away from friction.
So, there is 0 free energy left to recover - all of it is being taken away by friction.
If and only if, this is all understood,
we can go a bit more advanced and debunk the "wheel alternator".
Let's take a wind turbine, it takes away from the wind's speed (kinetic energy) - and converts that energy into electric energy.
This adds friction and slows down the WIND.
Same with a dynamo (a little generator powered by the wheel to run a light) on a bicycle -
it takes away from the wheel's energy - and converts in into light energy (Electromagnetic radiation)
So a 5W light, takes at least 5W away from the wheels energy, and that takes away from the bicycle's energy.
If you'd suddenly shut down the generator, you'd find your self accelerating -
because you were inputing at least 5W more than it was needed to go the speed you were going.
Basically, to run this 5W generator, you have to input at least 5W more than you otherwise would.
And the same goes for your idea!
let's say we want a wheel to generate 1kWh of energy,
As we previously understood, there's no free energy:
you'd have to add that 1kWh of energy to however much you already were using to go the speed you're going.
But in the real world, generators and battery charging systems are far from efficient,
a lot of energy doesn't end up in the battery (as chemical energy), a lot of it ends up wasted as heat (thermal energy)
So in other words, in our world with our current understanding of physics -
what you're talking about is not with in the realms of possibility. it literally voids the most basic pricipals we know.
In a more scientific manner,
This is all just an interpretation of Newtown's first law, ΣFv = 0
It roughly translates as "The sum of all vectors of force for an object in sustained motion is equal to 0"
Gravity (mg) and Normal (the floor pushing against you) are equal (Newton's Third Law) - so you aren't falling through the ground, nor are you floating.
And to sustain a speed, Friction (f) and Force (F) have to be the same.
The more energy you're taking away to generate something (and again, you have to take it from something - in your case it's also from the moving car) - the more you'll have to input to sustain the speed.
In other words, no there is not free energy.
To the forum members who are engineers, I know that not everything here is the most up to date theoretical physics, I did purposefully use simple terminology - it's just a simple explanation.
No, I am not talking about regenerative braking. what I am saying is this, if you have a charging unit connected to the drive train and it will mesh with a gear that is turned by the wheel. you are not using power, the power comes from the battery. if you had one connected to all the axels with each unit maintaining a charge that is controlled by a voltage switch so it won't overcharge, then you would have a consistent way of charging the battery, therefore there is no need to find a charging station. think of it as the same way your alternator works to charge the battery in your car times 4, the power is in the battery, not the starter.
You're still looking at a net loss of power if you're not adding any additional from outside the car itself and thus will still need to find a charging station.
https://www.physlink.com/education/askexperts/ae280.cfm