Electric vehicles cheaper than combustion by 2027, study predicts

[Elderberry]

That hand cart is actually not powerless. It contains gravitational potential energy.

http://hyperphysics.phy-astr.gsu.edu/hbase/gpot.html

Gravitational potential energy is energy an object possesses because of its position in a gravitational field. ... Since the force required to lift it is equal to its weight, it follows that the gravitational potential energy is equal to its weight times the height to which it is lifted. PE = kg x 9.8 m/s2 x m = joules.

[thackney]

Ok,so how does a powerless hand cart roll down a hill?

Gravity.

You charge that system pushing it up the hill.  That is the source of potential energy to roll back down the hill.

No different than lifting a weight and letting it fall, just adding an hill and a wheel to the system.

[HoustonSam]

You charge that system pushing it up the hill.  That is the source of potential energy to roll back down the hill.

But @sneakypete, if you connect the wheels on that powerless hand cart to a generator and push the cart down the hill, the cart will roll more slowly to the bottom.  Whatever energy you put into the hand cart by pushing it to the top of the hill is the only energy available to do anything while it's rolling back down the hill.  If you divert some of that energy into running a generator then less of the energy will go into the handcart's forward motion.  If the generator is large enough the cart won't roll at all, it will stay still on the slope of the hill.

The bottom line is that you can't create energy, you can only convert it from one form to another; every time you convert it some of it goes astray.  If you want to get energy out of a moving vehicle by powering a generator with the vehicle's turning wheels, you can only get the energy to run the generator from the vehicle's engine, and the generator will create less energy than the engine puts into it.  In your example case that engine is gravity.

A lot of folks have tried to beat this one for a long time, but it's like Supply and Demand in economics or gravity.  It is what it is, and we can't beat it.

[roamer_1]

I will defend @sneakypete on this a little bit.

If the purpose is augmentation, in recognition that the power produced cannot exceed the power that made it, the idea is sound.

Imagine if you would a doghouse on the back of a pickup, or a trailer built for same... a camper. Let's say there are two 12v car batteries that live in the camper to provide conveniences....

Now I know those batteries can be recharged using the alternator on the truck, But let's say we build a simple frame to allow a bicycle wheel to run along the ground behind, and attach an alternator to that frame, belt-driven from the bicycle wheel.

After a couple days in the woods, and the batteries are low, dragging that little wheel along the ground on the way home would certainly (tend to) recharge the system passively... At a pittance to the truck.

[Elderberry]

In your "passive?" example you are actually drawing more energy from the truck's engine than if you would just wire those batteries to the truck's alternator.

[DB]

I will defend @sneakypete on this a little bit.

If the purpose is augmentation, in recognition that the power produced cannot exceed the power that made it, the idea is sound.

Imagine if you would a doghouse on the back of a pickup, or a trailer built for same... a camper. Let's say there are two 12v car batteries that live in the camper to provide conveniences....

Now I know those batteries can be recharged using the alternator on the truck, But let's say we build a simple frame to allow a bicycle wheel to run along the ground behind, and attach an alternator to that frame, belt-driven from the bicycle wheel.

After a couple days in the woods, and the batteries are low, dragging that little wheel along the ground on the way home would certainly (tend to) recharge the system passively... At a pittance to the truck.

The energy still comes out of your gas tank (assuming the way home isn't all down hills...). And in all likelihood the alternator is more efficient than the wheel and the generator at recharging the battery. In other words, the wheel and generator will likely add slightly more drag than the alternator generating the same power. In fact the alternator is connected directly to the engine where as the wheel is being turned via the entire drive train which adds more losses before doing the added work.

Now... If the camp site were up a hill and you charged your battery with the external wheel generator coming back down the hill you really would charge your battery for free. Then you're taking advantage of the kinetic energy you added to your truck by increasing its elevation. The amount of energy going into your battery in that case reduces the amount of heat generated in your brakes/engine that was used to slow your truck down going back down the hill.

[HoustonSam]

At a pittance to the truck.

But that pittance is still greater than 0, and it’s more than we put into the batteries, which is the point.

[roamer_1]

In your "passive?" example you are actually drawing more energy from the truck's engine than if you would just wire those batteries to the truck's alternator.

Incidental to the point, and I already admitted as much. Still it would work. And I do not know that the drag at the hitch is necessarily more than the drag at the crank... One would have to ponder gearing and momentum and free-wheeling... But that is not my intention. In the end you are running two alternators instead of one, and providing there is room in the output of the first alternator, efficiency would favor the single alternator anyway.

But if you had some reason to require charging away from the main system, surely it would serve the purpose to recharge the camper system. If that is what you mean to do, then fine.

I did something similar, running a crappy air compressor head off the wheel of my trailer. I wanted right-now air, and it served that purpose for years. Generally, I never had to start the gas engine on the compressor, because the passive system did enough. I eventually abandoned the idea when I moved the air onboard the truck... But it suited my purpose for a long time.

The point being if it suits your purpose, then fine... It is incidental to the truck anyway. The finer points don't matter.

[roamer_1]

The energy still comes out of your gas tank (assuming the way home isn't all down hills...). And in all likelihood the alternator is more efficient than the wheel and the generator at recharging the battery. In other words, the wheel and generator will likely add slightly more drag than the alternator generating the same power. In fact the alternator is connected directly to the engine where as the wheel is being turned via the entire drive train which adds more losses before doing the added work.

Now... If the camp site were up a hill and you charged your battery with the external wheel generator coming back down the hill you really would charge your battery for free. Then you're taking advantage of the kinetic energy you added to your truck by increasing its elevation. The amount of energy going into your battery in that case reduces the amount of heat generated in your brakes/engine that was used to slow your truck down going back down the hill.

Like I said above, there is quite a bit to consider there... gearing, momentum, free-wheeling, etc... And efficiency may not be what is desired. Maybe I want to to charge faster, and the weight on the truck charging system other than the camper might call for a dedicated system. I don't know why. Perhaps it is a poor example.

[roamer_1]

But that pittance is still greater than 0, and it’s more than we put into the batteries, which is the point.

Right. But I don't think that was @sneakypete 's point. I don't think he was saying there is free power there - In fact he denied that he was looking for perpetual motion.

To illustrate by absurdity, I know that if one were to daisy-chain several of those wheel driven alternators and could somehow feed the power they were making back into the engine driving the chain, eventually you would reach a point where the engine could not pull the chain. There is of a necessity, a diminishing return.

But I am not dealing with an absurdity. What I am doing is incidental to the truck - a pittance - and if it serves a purpose, then the benefit outweighs the cost.

[Smokin Joe]

I will defend @sneakypete on this a little bit.

If the purpose is augmentation, in recognition that the power produced cannot exceed the power that made it, the idea is sound.

Imagine if you would a doghouse on the back of a pickup, or a trailer built for same... a camper. Let's say there are two 12v car batteries that live in the camper to provide conveniences....

Now I know those batteries can be recharged using the alternator on the truck, But let's say we build a simple frame to allow a bicycle wheel to run along the ground behind, and attach an alternator to that frame, belt-driven from the bicycle wheel.

After a couple days in the woods, and the batteries are low, dragging that little wheel along the ground on the way home would certainly (tend to) recharge the system passively... At a pittance to the truck.

Just ascharging the batteries from the alternator would do so at a pittance to the truck without an additional mechanical system to maintain.

I have a couple of old headlight setups, new in the box, from Schwinn, to put on your bike to generate electricity to run an headlight and taillight. But anyone who ever put one on their bike can tell you, it took more effort to run that little generator than most folks wanted to add to just getting somewhere. I still think they're neat, and I like the idea of being able to make light without a fire of batteries, but recognize the trade off. The alternator's losses due to friction, to magnetic resistance while generating current, are a pittance to the engine, and you don't have to devise or maintain any additional systems in contact with the ground. Might as well mount an alternator on the headache rack with a fan and use that, if you want a separate system, but either way, that trifiling input will show up somewhere in the loss of MPG. The question is one of which system is most efficient overall, which has the least losses to friction, which has the least outlay of capital, and which is easiest to maintain.

[roamer_1]

Just ascharging the batteries from the alternator would do so at a pittance to the truck without an additional mechanical system to maintain.

Already answered. If there is cause for the mechanism, then the benefit outweighs the cost - I don't know what that cause is - Like I said, perhaps my example is poor. But just like that cheap compressor head (which I got for nothing) served a purpose keeping my air tank always full on my trailer, The pittance it cost to run it off the wheel of my trailer was worth it to me.

I have a couple of old headlight setups, new in the box, from Schwinn, to put on your bike to generate electricity to run an headlight and taillight. But anyone who ever put one on their bike can tell you, it took more effort to run that little generator than most folks wanted to add to just getting somewhere. I still think they're neat, and I like the idea of being able to make light without a fire of batteries, but recognize the trade off.

Sure - And I don't deny that. I recognize the trade-off. What, a horse or two running full out? A pittance against that Chevy.

The alternator's losses due to friction, to magnetic resistance while generating current, are a pittance to the engine, and you don't have to devise or maintain any additional systems in contact with the ground. Might as well mount an alternator on the headache rack with a fan and use that, if you want a separate system, but either way, that trifiling input will show up somewhere in the loss of MPG. The question is one of which system is most efficient overall, which has the least losses to friction, which has the least outlay of capital, and which is easiest to maintain.

Not necessarily. Perhaps the extra alternator means faster charging. Less miles to get a full charge back in the camper. And that ain't no small thing. Filling two dead batteries don't happen in a minute. Maybe you ain't going home, but on to the next camp, and that full charge means you don't have to haul out a jenny or set up solar. Is that worth letting a wheel down to double your output?

Maybe so.

[Kamaji]

No Pete, I am trying to politely, respectively explain it does not work that way.

What you describe is a perpetual motion machine.


No,I am NOT.


In any power system, you can draw a box around a component or group of components and the power in must equal the power out or you have made a mistake in your calculation.

Just a wheel going round and round does not have any power that can be recovered without the power being taken from somewhere else.


Ok,so how does a powerless hand cart roll down a hill?



 

A powerless handcart rolls down a hill because of gravity, which is exerting a net, unbalanced force on the handcart.

[HoustonSam]

Right. But I don't think that was @sneakypete 's point. I don't think he was saying there is free power there - In fact he denied that he was looking for perpetual motion.

I don't want to put words in his mouth or mis-state his position, but I believe @sneakypete theorized that we can extend the range of an electric vehicle by using its turning wheels, or the wheels of an attached trailer, to power a generator and produce more electricity to power the vehicle.  We cannot, it's impossible.  We would draw more additional energy from the vehicle's battery to turn the wheels with the additional load of the wheel-powered generator than we would put back into the battery from that wheel-powered generator, consequently reducing the vehicle's range.

While no one intends to suggest perpetual motion in this thread, if we could extend the range of the vehicle this way, then we would extend it even further while driving through that additional range, and further still while driving through that next additional range, etc.  We'd be getting more energy out of the system than had been put into the system, which is a definition of perpetual motion.

There are any number of ways we can draw power off a running engine or electric motor to re-charge batteries, run heaters, etc; no one is arguing that can't be done or that it's a bad idea.  What we are saying is that all of those approaches, including re-charging the batteries that drive the vehicle, will reduce a vehicle's range between re-charging or fill-ups.

[Cyber Liberty]

I don't want to put words in his mouth or mis-state his position, but I believe @sneakypete theorized that we can extend the range of an electric vehicle by using its turning wheels, or the wheels of an attached trailer, to power a generator and produce more electricity to power the vehicle.  We cannot, it's impossible.  We would draw more additional energy from the vehicle's battery to turn the wheels with the additional load of the wheel-powered generator than we would put back into the battery from that wheel-powered generator, consequently reducing the vehicle's range.

While no one intends to suggest perpetual motion in this thread, if we could extend the range of the vehicle this way, then we would extend it even further while driving through that additional range, and further still while driving through that next additional range, etc.  We'd be getting more energy out of the system than had been put into the system, which is a definition of perpetual motion.

There are any number of ways we can draw power off a running engine or electric motor to re-charge batteries, run heaters, etc; no one is arguing that can't be done or that it's a bad idea.  What we are saying is that all of those approaches, including re-charging the batteries that drive the vehicle, will reduce a vehicle's range between re-charging or fill-ups.

I took a test drive with an EV1 (back before they cancelled all the leases and crushed the cars), and they had a feature that used a generator from the wheels when you took your foot off the "gas" pedal as you approached a traffic signal.  It slowed the car down without using the brakes, and pushed more charge into the battery.  It was to help extend the range.  I assume modern electrics have this feature.

The car had amazing low-end torque.  It had a lot of power, but handled like a Chevette.

[thackney]

I took a test drive with an EV1 (back before they cancelled all the leases and crushed the cars), and they had a feature that used a generator from the wheels when you took your foot off the "gas" pedal as you approached a traffic signal.  It slowed the car down without using the brakes, and pushed more charge into the battery.  It was to help extend the range.  I assume modern electrics have this feature.

The car had amazing low-end torque.  It had a lot of power, but handled like a Chevette.

Exactly right.  This is what improves the electric vehicles in stop and go city traffic.  It takes energy to turn the generator.  The more energy you try to take out of it, the harder it is to turn, the more it works like a brake in this example.

[Cyber Liberty]

Exactly right.  This is what improves the electric vehicles in stop and go city traffic.  It takes energy to turn the generator.  The more energy you try to take out of it, the harder it is to turn, the more it works like a brake in this example.

Which is exactly the same way a diesel/electric railroad engine slows the train without burning out the brakes. 

[HoustonSam]

I took a test drive with an EV1 (back before they cancelled all the leases and crushed the cars), and they had a feature that used a generator from the wheels when you took your foot off the "gas" pedal as you approached a traffic signal.  It slowed the car down without using the brakes, and pushed more charge into the battery.  It was to help extend the range.  I assume modern electrics have this feature.

The car had amazing low-end torque.  It had a lot of power, but handled like a Chevette.

No surprise this slowed the vehicle down.  But the point in this thread is what I've highlighted - can the vehicle's range be extended this way?  That is pete's theory and apparently what Cyber was told as well.  For reasons I've tried to elaborate, I don't believe it.

[Cyber Liberty]

No surprise this slowed the vehicle down.  But the point in this thread is what I've highlighted - can the vehicle's range be extended this way?  That is pete's theory and apparently what Cyber was told as well.  For reasons I've tried to elaborate, I don't believe it.

I made no such claim.  What I described really does extend the range, because it uses the potential energy of inertia that has to be overcome anyway to stop the car for a traffic signal to recharge the battery.

[HoustonSam]

I made no such claim.  What I described really does extend the range, because it uses the potential energy of inertia that has to be overcome anyway to stop the car for a traffic signal to recharge the battery.

Yeah I've tried to sort out how inertia would play into this.  For the momentary period when the driver's foot is off the "gas" we are drawing minimally from the battery so wheel-generated power added back to the battery might be a net positive.

I suppose it depends on how we describe the cases for comparison.  Capturing energy from inertia during each stop-start cycle would certainly be better than not capturing energy from inertia during each stop-start cycle, so for stop-start city driving I can see how one would argue the range is extended.  But I would expect steady-speed highway driving to have a longer range than either of these stop-start cases, and that range to be impeded by continual recharging from wheel-generated incremental power.

[roamer_1]

I don't want to put words in his mouth or mis-state his position, but I believe @sneakypete theorized that we can extend the range of an electric vehicle by using its turning wheels, or the wheels of an attached trailer, to power a generator and produce more electricity to power the vehicle.  We cannot, it's impossible.  We would draw more additional energy from the vehicle's battery to turn the wheels with the additional load of the wheel-powered generator than we would put back into the battery from that wheel-powered generator, consequently reducing the vehicle's range.

While no one intends to suggest perpetual motion in this thread, if we could extend the range of the vehicle this way, then we would extend it even further while driving through that additional range, and further still while driving through that next additional range, etc.  We'd be getting more energy out of the system than had been put into the system, which is a definition of perpetual motion.

There are any number of ways we can draw power off a running engine or electric motor to re-charge batteries, run heaters, etc; no one is arguing that can't be done or that it's a bad idea.  What we are saying is that all of those approaches, including re-charging the batteries that drive the vehicle, will reduce a vehicle's range between re-charging or fill-ups.

I will leave @sneakypete to speak for himself.

I reject the idea that a towed platform can generate anywhere near the power of the vehicle towing. There has to be a diminished return... And normally that is large.

My point is  that used within a reasonable parameter, the idea is sound. Certainly a drag that is but a pittance (a horse or two) is within the realm of 'doable' and acceptable (loss).

I do not mean to propose anything more.

[Cyber Liberty]

Yeah I've tried to sort out how inertia would play into this.  For the momentary period when the driver's foot is off the "gas" we are drawing minimally from the battery so wheel-generated power added back to the battery might be a net positive.

I suppose it depends on how we describe the cases for comparison.  Capturing energy from inertia during each stop-start cycle would certainly be better than not capturing energy from inertia during each stop-start cycle, so for stop-start city driving I can see how one would argue the range is extended.  But I would expect steady-speed highway driving to have a longer range than either of these stop-start cases, and that range to be impeded by continual recharging from wheel-generated incremental power.

That part I highlighted is 100% correct.  What I described earlier does not apply to a long, no stop drive because there is no braking.  It helps in city driving where there is a lot of stop and go.

[Cyber Liberty]

I will leave @sneakypete to speak for himself.

I reject the idea that a towed platform can generate anywhere near the power of the vehicle towing. There has to be a diminished return... And normally that is large.

My point is  that used within a reasonable parameter, the idea is sound. Certainly a drag that is but a pittance (a horse or two) is within the realm of 'doable' and acceptable (loss).

I do not mean to propose anything more.

That's right.  The picture I saw posted upthread about a small trailer is not a generator, it's an auxiliary battery, like the "piggyback" batteries they used to have for cell phones.

[roamer_1]

That's right.  The picture I saw posted upthread about a small trailer is not a generator, it's an auxiliary battery, like the "piggyback" batteries they used to have for cell phones.

Sure.

And I suppose that a trailer could tow a generator big enough to power the car - or come close - But that generator would need a fuel source onboard (and frequent replenishment), defeating the purpose of an electric car.

As to the trailer battery,
CERTAINLY, according to the size of the batt in the vid upthread, Multiple instances of that could be towed along on a trailer behind, resulting in a remarkably extended distance.

[Bigun]

The idea that battery powered vehicles are going to replace those powered by internal combustion engines anytime in the foreseeable future is made up of