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Saluki
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quote:
Originally posted by john crusher:
I've always wondered why they can't figure out how to generate power for recharge through the non-drive wheels.
If they had an alternator assy. incorporated in the free wheels then why wouldn't it work?

That lesson was learned as a youngster and a generator driven headlight on my bicycle.


----------The weather is here I wish you were beautiful----------
 
Posts: 5452 | Location: southern Mn | Registered: February 26, 2006Reply With QuoteReport This Post
Peace through
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Picture of parabellum
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quote:
Originally posted by arcwelder:
Apologies, I've long been to blunt.
I don't want to hear any Goddamned apologies or excuses or explanations from you. I want you to do what I'm telling you I require from you and that I've told you several times now.

You will be POLITE to everyone here at all times. You will stick to the subject at hand and refrain from vague non sequitur comments. You think you're being profound? You're not. Get it? You're not. Stick to the subject, make your comments clear and understood. Address what's being discussed and nothing more than that.

Do you really want to be here? Do you really want to be a member of this forum? Let me tell you- if I had opened this thread today and saw no response from you, I would have pulled the trigger. Do you care? If you care, stop wasting my Goddamned time with having to babysit you.

And stay the fuck out of this forum when you're drinking. You're mean when you're drunk, man, and I don't want to see the kind of shit I've seen from you in your late night rambles. Am I getting through to you?

Don't like what I'm telling you? Then, leave. Behave yourself like everyone else here behaves themselves, or leave. You've used eight of your nine lives, kitty cat. Just give me a reason.
 
Posts: 114171 | Registered: January 20, 2000Reply With QuoteReport This Post
Peace through
superior firepower
Picture of parabellum
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quote:
Originally posted by ss9961:
What about the laws of thermodynamics?
How is it possible that nobody has mentioned
the laws of thermodynamics?

Seriously guys. You’re all forgetting the laws of thermodynamics.

Page 1:
quote:
Originally posted by parabellum:
Physics: conservation of energy
 
Posts: 114171 | Registered: January 20, 2000Reply With QuoteReport This Post
Savor the limelight
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In other words, it’s against the law.
 
Posts: 14382 | Location: SWFL | Registered: October 10, 2007Reply With QuoteReport This Post
Spider two-wide banana
Picture of DoctorSolo
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It's easy to lose track of practical considerations when we discuss these "wouldn't it be nice" scenarios.

It's easier to understand the difficulty of the problem when you quantify the requirements. I'm trying to expand on snidera's point.

The total amount of energy available from 1 square meter of solar light is 1kW. Real solar cells have thermal and electrical losses, so are much less efficient than that, so that number is practically 5-30% if what is available.

Let's set that aside, a typical tesla battery stores on the order of 75kWh.

If you have a 1 meter square IDEAL solar cell, you will take 75 hours of direct sunlight exposure to charge the battery, and this is neglecting the car's own power system losses from the charger to the cell(it aint 100% either).

Getting back to a practical example, cover the whole car with modern solar panel, probably 3 square meters now, but only 30% efficient. We are back to about 1kW of power to charge the giant battery during ideal daytime conditions.

A Tesla burns 1kW-hour in about 3 miles.

You need a LOT of power to charge an EV, and it's a testament to how cheap electricity still is in this country, that it's very practical.
 
Posts: 5400 | Location: Colorado Springs | Registered: April 12, 2006Reply With QuoteReport This Post
Don't Panic
Picture of joel9507
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quote:
Originally posted by old rugged cross:
You guys are stuck in the past and the current.

Better stated...they understand the laws of conservation of energy and of thermodynamics, which will apply to the future as well as they do the past and the current.

There's a base amount of energy needed to move masses around, overcome friction, wind resistance, run display screens, play music, provide heat/cooling for the interior, etc., all the things cars do. That needs to be gathered in, stored, and converted to motion.

If you want the car itself to do the gathering, you're making the job harder yet, as now the weight of whatever contraption you imagine will be doing that would need to be added into the mix.
 
Posts: 15730 | Location: North Carolina | Registered: October 15, 2007Reply With QuoteReport This Post
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Picture of Prefontaine
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I’ve had panels on the house since 2014 and a cheap, inexpensive EV leased (later bought from them) during the same time. kWh for the vehicle have been next to nothing. I’ve bought rural land and am designing more elaborate solar system, adding a windmill, inverter, and generator. You could say off the grid, but I will connect to the grid, just to bank kWh credits and help my neighbors out. And I will keep a donkey EV (something very inexpensive and likely upgrading my 12 year old Leaf to the new Slate EV when it comes out since it will have double to triple the range of my old POS) so that necessity driving is essentially free.
Making your own power is where a cheap EV makes sense. Fancy/luxury EV’s that cost a lot of money have never made sense to me.



What am I doing? I'm talking to an empty telephone
 
Posts: 14164 | Location: Down South | Registered: January 16, 2010Reply With QuoteReport This Post
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Solar panels on the roof of an EV would be neat, charging the batteries passively at almost all times.

Problem is, the amount of energy hitting the Earth from the sun is about 3 watts per square foot, so at 100% efficiency a solar panel would need to be the size of your house to charge a typical Tesla battery in 8 hours.
 
Posts: 3744 | Location: Nashville | Registered: July 23, 2012Reply With QuoteReport This Post
Green grass and
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Picture of old rugged cross
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quote:
Originally posted by bobtheelf:

Problem is, the amount of energy hitting the Earth from the sun is about 3 watts per square foot, so at 100% efficiency a solar panel would need to be the size of your house to charge a typical Tesla battery in 8 hours.


a current tesla battery and a current solar panel. . I get it. But do you think 25 years ago most people thought things possible today would of been possible?

I do believe in the goal post being moved.

It has been repeated several times in this thread the concept of thermal dynamics, etc. etc. etc.


Things are a changing and I do think thinks thought impossible will become possible.



"Practice like you want to play in the game"
 
Posts: 21573 | Registered: September 21, 2005Reply With QuoteReport This Post
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Picture of steve495
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quote:
Originally posted by old rugged cross:
quote:
Originally posted by Mercury:
If the skin of the car was a large solar panel, it would provide some charging whenever the car was out in the sunshine. This would help to extend the range while driving and provide charging while sitting in a parking lot all day long.

Maybe it exists and is already in use?


Yes, something like this. There is no doubt some forward thinking technology that will accomplish this.


I seem to recall Musk being asked this question. The surface area of the roof/car does not offer enough usable area to power the car. Of course weight is part of it, and adding panels adds weight.

I asked ChatGPT about it. Take it for what it is worth.

quote:
You're right — and Musk’s comment gets to the heart of the issue: solar panels on a car can technically replenish the EV battery, but only very slowly, because of physics and space limitations.

Let’s break it down:

1. Power Density Limits

Typical high-efficiency solar panels today produce about 200–250 watts per square meter (best commercial cells can reach ~300–350 W/m² in perfect sun). That’s about 20–25% efficiency, which is close to the theoretical limit for current silicon technology.

A car roof and hood might give you 2–5 m² of usable area, depending on the vehicle. Even if you had 5 m² of perfect panels getting 1,000 W/m² of full sunlight:

5 m² × 250 W/m² = 1,250 watts (1.25 kW)

That’s about the same as a hair dryer on low — and that’s only when the sun is strong and directly overhead.

2. What That Means in Driving Terms

Let’s say your car consumes 250 Wh/mile (a typical EV efficiency).

1.25 kW for 5 hours of good sunlight = 6.25 kWh generated

6.25 kWh ÷ 0.25 kWh/mile = ~25 miles of range added per sunny day

That’s under ideal conditions — in reality, shading, panel angle, clouds, and dirt all reduce output. Real-world results might be more like 10–20 miles per day of extra range.

3. Why It’s Still Rare

The surface area of a car is small compared to its energy needs.

Panels add cost, complexity, and weight.

Cars are often parked in shade or garages, not in full sun.

Musk and others (including Toyota and Aptera) have experimented, but Musk said Tesla didn’t find it practical for most customers — the payoff was too small relative to cost.

4. When It Can Help

Some vehicles like the Lightyear 0, Sono Sion (canceled), and Aptera claim 15–40 miles/day from solar alone, using ultra-efficient aerodynamics and lightweight builds.
For conventional EVs (like Tesla, Hyundai Ioniq 5, etc.), solar roofs are useful for trickle charging accessories or battery maintenance, but not for fully replenishing driving range.

In short:
Musk was right — solar panels are already near their practical power-per-square-foot limit. You can add range with on-vehicle solar, but it’s modest — enough for free trickle charging, not full daily driving.


Steve


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Posts: 5093 | Location: Babcock Ranch, Fla. | Registered: July 18, 2006Reply With QuoteReport This Post
thin skin can't win
Picture of Georgeair
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quote:
Originally posted by old rugged cross:

a current tesla battery and a current solar panel. . I get it. But do you think 25 years ago most people thought things possible today would of been possible?


You don't seem to be picking up what folks are laying down.

How will you modify the SUN to increase it's output?!?! Well, technically our receipt of output.

Want something for EV other than sun, like nuclear, hydrogen, etc.? Same math problem of net<100% over the arc of production. Much less.

Even approaching your dream will take a completely different technology than electric, or a means of generating it that defies physics. We'll get more efficient no doubt, but no matter what not 100%.



You only have integrity once. - imprezaguy02

 
Posts: 13532 | Location: Madison, MS | Registered: December 10, 2007Reply With QuoteReport This Post
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quote:
Originally posted by old rugged cross:

a current tesla battery and a current solar panel. . I get it. But do you think 25 years ago most people thought things possible today would of been possible?

I do believe in the goal post being moved.

It has been repeated several times in this thread the concept of thermal dynamics, etc. etc. etc.


Things are a changing and I do think thinks thought impossible will become possible.


No, I mean at 100% efficiency, the total amount of energy from the sun hitting the earth under perfect conditions is about 3 watts per square foot. That has nothing to do with the panel capturing that energy.

Nothing can capture more energy than is being input in to the system. Electric motors may get more efficient, but there are baseline numbers fixed by the laws of physics that cannot be overcome.
 
Posts: 3744 | Location: Nashville | Registered: July 23, 2012Reply With QuoteReport This Post
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Picture of konata88
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This is not necessarily technically possible or safe (as I describe it). But perhaps I can be made to be so through different implementations.

Question: why does the power source need to be contained w/ the car? Like solar panels. Wouldn't it be acceptable to just have the batteries be replenished quickly and easily?

If so, how about something conceptual like gas stations and/or on-road "toll booths" where you drive through and get an instant charge, wireless charge. Like a bolt of tesla lightning unencumbered by amperage limitations of house wires.

Anyway, the concept is almost instantaneous transfer of power, convenient, safe and scalable (1 power source for many, not 1:1).

Like supplying 1.21 GW to a delorean. Yes, I know the battery is currently limited to how fast it can recharge. But again, technical limitations today. Again, just a conceptual methodology, not a solution.




"Wrong does not cease to be wrong because the majority share in it." L.Tolstoy
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Posts: 14785 | Location: In the gilded cage | Registered: December 09, 2007Reply With QuoteReport This Post
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Picture of Perception
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quote:
Originally posted by old rugged cross:
quote:
Originally posted by bobtheelf:

Problem is, the amount of energy hitting the Earth from the sun is about 3 watts per square foot, so at 100% efficiency a solar panel would need to be the size of your house to charge a typical Tesla battery in 8 hours.


a current tesla battery and a current solar panel. . I get it. But do you think 25 years ago most people thought things possible today would of been possible?

I do believe in the goal post being moved.

It has been repeated several times in this thread the concept of thermal dynamics, etc. etc. etc.


Things are a changing and I do think thinks thought impossible will become possible.


I don't know what the future holds, but right now it's not possible with the realities we currently contend with. If we suspend those for the sake of the discussion though, literally anything you can imagine is possible.

It's possible that they will nail down long range energy transmission eliminating batteries and charging completely. It's possible we'll have some kind of new propulsion that will eliminate the need for any kind of engine/ motor on the vehicle itself. It's possible someone will figure out Star Trek style transporters, eliminating the need for vehicles completely. You'll step out your front door and be at your destination.




"The people hate the lizards and the lizards rule the people."
"Odd," said Arthur, "I thought you said it was a democracy."
"I did," said Ford, "it is."
"So," said Arthur, hoping he wasn't sounding ridiculously obtuse, "why don't the people get rid of the lizards?"
"It honestly doesn't occur to them. They've all got the vote, so they all pretty much assume that the government they've voted in more or less approximates the government they want."
"You mean they actually vote for the lizards."
"Oh yes," said Ford with a shrug, "of course."
"But," said Arthur, going for the big one again, "why?"
"Because if they didn't vote for a lizard, then the wrong lizard might get in."
 
Posts: 3768 | Location: Two blocks from the Center of the Universe | Registered: December 30, 2004Reply With QuoteReport This Post
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Right!

but before we achieve some of those things.
A self charging or no charge ev seems likely sooner than later. Wink



"Practice like you want to play in the game"
 
Posts: 21573 | Registered: September 21, 2005Reply With QuoteReport This Post
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My wife has a Mazda CX90 plug-in hybrid. It has a small 17kWh rechargeable battery. The battery assists with providing power along with the engine. Fully charged the battery will drain in about 25 miles and takes about 12-14 hrs to charge using a standard 20 amp 110 outlet. It really puts the power in to power out ratio in perspective.


 
Posts: 5670 | Location: Pittsburgh, PA, USA | Registered: February 27, 2001Reply With QuoteReport This Post
Void Where Prohibited
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We'll have unlimited power once they figure out how to harness element 115 like the aliens do ...
Big Grin



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Posts: 17109 | Location: Under the Boot of Tyranny in Connectistan | Registered: February 02, 2005Reply With QuoteReport This Post
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Originally posted by old rugged cross:
A self charging or no charge ev seems likely sooner than later. Wink

Nope. Read all the comments on this thread from folks that understand physics, energy efficiencies, mechanical efficiencies, electrical systems, solar & wind systems.

Perpetual motion only worked with Wile. E. Coyote cartoons, with his excellent Acme products.
 
Posts: 8432 | Location: Colorado | Registered: January 26, 2008Reply With QuoteReport This Post
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Picture of bobtheelf
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quote:
Originally posted by old rugged cross:
Right!

but before we achieve some of those things.
A self charging or no charge ev seems likely sooner than later. Wink


The limitation is not technology.

The limitation is physics.
 
Posts: 3744 | Location: Nashville | Registered: July 23, 2012Reply With QuoteReport This Post
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Here's an idea: we run overhead power lines with a tether connected to the vehicle to power the electric motor, or install power strips in the road that the car contacts as it drives over them. Wink
 
Posts: 2855 | Location: WI | Registered: December 29, 2012Reply With QuoteReport This Post
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