Electric Car Debate

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dereckbc said:
Jon good comments. I do not know the total weight of a Corvette with the engine and full fuel load, but the batteries alone in the Telsa are 1000-pounds (450 KG) and I am clueless what the total weight and the electric motor weigh. My educated guess is the Telsa weighs more than a Corvette, and if that is true, no way can it use 200 watt-hours per mile @ 60 mph.

Other unknowns are things like heat, AC, lights, power steering, brakes, etc. All these things would require power that so far has not been taken into account.
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My 1979 has a curb weight of 3,500 pounds, or a total wet-weight, including one Julie, of about 3,900 pounds. Newer Corvettes have a curb weight of 3,100 to 3,200 pounds.

Tesla gives the curb weight of their car at 2,500 pounds.

Remember that the engine and transmission in a Corvette, to say nothing of the driveline, are not especially light. You're counting the 1,000lb battery pack of the Tesla, but not "crediting" them the missing engine, transmission, drive shaft, and 24 gallon (what mine carries) tank full of gasoline.
 
Man (and woman)...you guys are sure getting technical. Here's some simple facts to throw into the mix.

1 HP is the work produced to lift
550 pounds...1 foot... in 1 second
or
33000 pounds...1 foot...in 1 minute
Some movement has to take place in the load to calculate Horsepower.
It may be ...
3168000 pounds...1/8 inch...in one minute..
or
1 ounce....528000 feet...in 1 minute
or
23760000000 pounds...001 inch... in 1 second
Something has to move for work to be produced.

Horse power is a unit of work. These numbers were arrived at by James Watt, a early steam engineer designer/engineer. These numbers are a average of multiple tests conducted by Mr. Watt using real live horses to see how much work they could produce in a given amount of time.

Torque is not a factor in this unit, unless the Horsepower is converted to a twisting (or turning) motion to produce the work.
Then Horsepower becomes the work required to produce
550 foot pounds of torque for 1 second
or
33000 foot pounds of torque for 1 minute
and
is equivalent to 745.7 Watts (of heat) per hour..or 2542 btu per hour..or 42.4 btu per minute.
Torque is a value of force times distance
Horsepower is a unit of work.
I hope that my math is correct.
Food for thought, feel free to critique.
steve
 
Lou, my statement was made in jest about the previous page's posts. If I had realized my post was going to wind up on the next page, I would have quoted the posts to make the joke make more sense.

iwire said:
tallgirl said:
who cares how many horsepower a car needs out of a gasoline motor?
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Who cares how much torque an electric motor can make when the power supply is inadequate?
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Kidding aside, I actually do think the issue is very relevant, and will become more so as time goes on. :)
 
Well after finding Tesla's web site and looking at their specs and claims, I am convinced they are misleading if not flat out lies.

For example they claim 1-cent a mile cost of electricity. Well using their 250-mile range and 50 KWH battery capacity, here in Texas using the best electric rate of 13-cents per KWH I get about 2.6 cents per mile ([50 x .13] / 250). However this figure is still too low, because it takes more than 50 KWH to charge a 50 KWH battery, more like 55 to 60 KWH once you include both rectifier and battery efficiencies. To get to 1-cent per mile, you would have to have an electric rate of 5-cents per KW. Anyone pay 5-cents per KW? If so let me know, I will move there.

Another glaring overstatement is greater than 100,000 miles before the battery degrades. This is a flat out lie. Any Lithium battery starts to degrade as soon as it leaves the factory. Lithium Ion batteries degrade with time, temperature, and number of recharges. Assuming it is never used; a Lithium Ion battery loses capacity based on storage temperature at a rate of 6% per year at 32 F, 20% per year at 72 F, 35% per year at 100 F, and 40% per year at 140 F. So in the real world where it is used by constant recharge and discharge cycles you would only get 2 to 4 years at best. This is supported by all the other BEV?s requirements of changing out the batteries every 25,000 to 30,000 miles or every 3 years whichever comes first.

Since there are over 6800 battery cells in this thing needing to be replaced every two or three years at a cost of I am certain in the 6-digit range, will certainly add significant cost per mile. With a base sticker price or $96,000, I?ll pass.

With just these 2 overstatements (flat out lies IMHO), I don?t believe any statement made by Telsa other than maybe 130 mph top speed and 0-60 in 4-seconds.
 
Responding to hillbilly:

I believe that you are wrong in some of your simple facts.

horsepower is not a unit of _work_, it is a unit of _power_. They are related in that power is the rate at which work is done.

Power is related to work in the same way that speed is related to position. Speed is the rate at which position changes.

You can have a speed of 1000 miles per hour over a time of 1 second, or even 1/1000 second. The shorter the duration, the shorter the actual distance moved over the duration in question. Using the mathematical concept of a 'limit', speed remains defined and definable as the duration in question approaches zero.

Speed times force give a result in units of power. This can be linear speed times linear force, or it can be rotational speed times rotational force (torque). This is still mechanical power, and can be measured in units of kilowatts, horsepower, or foot-pounds per second.

speed (measured in meters per second) * force (measured in newtons) gives power (measured in watts)

rotational speed (measured in radians per second) * torque (measured in newton-meters) gives power (measured in watts)

rotational speed (measured in RPM) * torque (measured in foot pounds) /5252 gives power (measured in horsepower)

speed (measured in feet per second) * force (measured in pounds) / 550 gives power (measured in horsepower)

rotational speed (measured in RPM) * torque (measured in foot pounds) *0.142 gives power (measured in watts)

And so on.

-Jon
 
hillbilly said:
Torque is not a factor in this unit, unless the Horsepower is converted to a twisting (or turning) motion to produce the work.
Then Horsepower becomes the work required to produce
550 foot pounds of torque for 1 second
or
33000 foot pounds of torque for 1 minute
and
is equivalent to 745.7 Watts (of heat) per hour..or 2542 btu per hour..or 42.4 btu per minute. Torque is a value of force times distance
Horsepower is a unit of work.
I hope that my math is correct.
Food for thought, feel free to critique.
steve
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It doesn't take any power to apply torque unless something is rotating.

One horsepower is the work required to apply 550 ft-pounds of torque to a device that is rotating at one radian per second, or to apply 33,000 ft-pounds of torque to a device that is rotating at one radian per minute.
 
Bob NH said:
It doesn't take any power to apply torque unless something is rotating.
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Yes and no. Putting a brick on the end of a board applies torque without requiring power. Putting an electric field in a motor requires power to generate and maintain the field. Running an engine that is applying torque through a fluid clutch (say, your car's torque converter) requires power.

More accurately, torque applied to something that isn't rotating isn't providing power. It might require power to generate that torque, but in that case the power is lost.
 
tallgirl said:
Putting a brick on the end of a board applies torque without requiring power.
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Not true, gravity is the power and it must remain constant during the time the given amount of torque is applied.

Torque can not be present without power period.

Roger
 
roger said:
Not true, gravity is the power and it must remain constant during the time the given amount of torque is applied.

Torque can not be present without power period.

Roger
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I respectfully disagree.

I put a 1 pound brick on the end of a 10ft board. The board is rigidly affixed on its end and is unable to rotate about the point of attachment. The brick causes an additional 1" deflection when the brick is placed there, but the movement stops immediately afterwards. I measure, using the appopriate device, the torque about the point of attachment and get a value of 10ft-lbs of torque.

What's the power produced by gravity after the brick has sat on the end of that board for, say, 1 hour? What's the torque after that hour has elapsed? What is the torque the next day? And the power being produced by gravity the next day?

Gravity (and torque) is a force, the same as "volts". Just as you can have an open terminal voltage and no power (because there is no current flow -- P = EI, I = 0), you can have a linear force caused by gravity (the brick is on a string) and a rotational force caused by gravity (the brick is on a board). Unless the object is moving, there is no power. Just as there is no power coming from an outlet with nothing plugged into it, but there is still a voltage present.
 
tallgirl said:
Unless the object is moving, there is no power.
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Sorry Julie, you have missed the boat again.

If the board is "flexed" from an opposing force it is under the influence of some maintained power source period.

Remove the force of gravity and the board goes back to its relaxed position, until this force is removed the board is experiencing an affect caused by this source of power.

Further more, with all the links provided in this thread the problem is "Today's scientists have substituted mathematics for experiments, and they wander off through equation after equation, and eventually build a structure which has no relation to reality.” Nikola Tesla

Roger
 
Not so:

Not so:

roger said:
Not true, gravity is the power and it must remain constant during the time the given amount of torque is applied.

Torque can not be present without power period.

Roger
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Gravity is a force commonly measured in pounds. Power is measured in foot-pounds/second. It is the rate at which work is done.

Take the product of force and distance to obtain work--commonly measured in foot-pounds. For example if I climb a 10-foot flight of stairs, I have expended 200 pounds x 10 feet = 2000 foot-pounds of work. If I do this in 10 seconds, the power is:

(2000 foot-pounds/10 sec) x 1 hp/(550 foot pounds/sec) = 0.18hp

Torque is also measured in foot-pounds, but torque is not a measure of work! One must be careful here.

The power delivered from a spinning motor would be,

2pi x r x f/T in foot-pounds/sec where "T" is the period of rotation, "f" is the force at the end of the crank, and "r" is the length of the crank.

The torsion springs in a garage door mechanism exert torque for hours on end with no power applied.
 
rattus said:
The torsion springs in a garage door mechanism exert torque for hours on end with no power applied.
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Rattus, power is being applied it is just not being used, it is simply waiting until it is unleashed so the rules of physics can take place as they are trying to do in this cocked state, remember, for every action there is an equal and opposite reaction.

I know some one on this forum will probably try to change this fact though.

A relaxed spring is not seeing any force applied or exerted, a charged spring is in a constant resistance trying to overcome the force of power that has it charged.

We need to forget all the "equations and formulas" and get back to the rules of nature.

Roger
 
Electric car

Electric car

Electric cars will work but American Manufactures will not hear from any one but a in house engeneer. There is already the knowledge needed to get there with a electric /combination gas car that works. We souldnt be reaching so far on this. we need to shave off a little more fule consumption not try to eliminate internal combustion engine. Not too much battery, Regeneration of electricity instead of braking. Using electric to run at slow speeds, internal combustion engine to run and maintain higher sustainable speeds. If we just did this it would save an increadable amount of fule. Any car or truck can be outfitted this way and we issentaly give up nothing but so dirty air.
 
Semantics:

Semantics:

roger said:
Rattus, power is being applied it is just not being used, it is simply waiting until it is unleashed so the rules of physics can take place as they are trying to do in this cocked state, remember, for every action there is an equal and opposite reaction.

I know some one on this forum will probably try to change this fact though.

A relaxed spring is not seeing any force applied or exerted, a charged spring is in a constant resistance trying to overcome the force of power that has it charged.

We need to forget all the "equations and formulas" and get back to the rules of nature.

Roger
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Roger, you are using the layman's definition of power which is inappropriate in this discussion. We must follow the rules and definitions of physics. If we are sloppy in our use of terms, we cannot communicate.

If no work is being done, the power is zero. If we have torque with no motion, there is no work, therefore no power. If we have two kids balanced on a seesaw, there is torque but no motion, therefore no power.

If we have voltage and no current, the power is zero. If we have current and no voltage, the power is zero.

A charged spring exerts a force, and there may or may not be any motion involved.

The brick on the board exerts a force not power on said board just like the kids on the seesaw exert forces on the seesaw.
 
perry vogler said:
If we just did this it would save an increadable amount of fule. Any car or truck can be outfitted this way and we issentaly give up nothing but so dirty air.
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How is this possible when it takes fossil fuel to generate the electricity? All you are doing is taking the fossil fuel from your car to the POCO generation plant and taking losses in the distribution system, a net increase in fuel consumption. There is a way around it, nuclear.
 
dereckbc said:
How is this possible when it takes fossil fuel to generate the electricity? All you are doing is taking the fossil fuel from your car to the POCO generation plant and taking losses in the distribution system, a net increase in fuel consumption. There is a way around it, nuclear.
Click to expand...

Wind or hydroelectric power might make it feasible as well.
 
Roger,

I'm going to jump on the bandwagon and say that Julie and rattus have this point.

_Power_ as used in the technical sense means the rate at which work is done.

Work is equivalent to force times distance; it could be volts times amp-seconds, or it could be pressure times volume change, or any of a number of other forms, but it all boils down to force times distance.

_Power_ is equivalent to force times speed; it could be volts times current, or pressure times volume flow, or something else that boils down to force times speed.

_Power_ is often used colloquially as you describe; in the same ways that a layperson will say that a circuit has 'power' of 240V. It is an entirely reasonable use of language, but because it conflates different related aspects of the physics, using it this was will simply confuse a physics discussion.
(This sort of confusion is often used _intentionally_ to try to sell perpetual motion machines, eg. demonstrating a magnet sticking to some metal and claiming that this magnet is generating 'power' without consuming any fuel.)

-Jon
 
Rattus, the only thing holding the power in check is a brake of some sort which is experiencing a constant pressure from this power source.

For a simple experiment to show this is the case cock a multi thousand pound recoil spring with a lever and insert a 1/2" steel pin across the springs races to hold it in place and release the lever, it is being stalled but it is there.

Now engage the lever again, remove the pin and insert your finger, release the lever, after your finger is severed from your hand measure the amount of time it took from releasing the lever to amputation and calculate the torque pressure from the phantom or non existent power source that relieved you of your finger.

Just because a force of power is being held back does not mean it doesn't exist or is not present.

Roger
 
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