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07/17/2008 09:04:06 PM · #1
Hello,

I had a discussion today with someone.

They said that there is surely a way to build a car that runs completly on battery power. They said it would have two batteries. As one battery powered the car, the other would get charged up from power generated by the turning wheels.

I said that is possible but in a short time both batteries would drain and need to be recharged by an external power supply. The other guy said "no it wouldn't". He says that the turning wheels would always charge the "other" battery and it would run basically "forever".

He feels that this car could be built but oil companies would crush it's development for obvious reasons.

I have a Biology Degree that included 4 semiesters of of physics. To have his theroy work would mean a complete breakdown of the thermodynamic laws.

What do you think...am I right?
07/17/2008 09:09:40 PM · #2
Originally posted by kenskid:

Hello,

I had a discussion today with someone.

They said that there is surely a way to build a car that runs completly on battery power. They said it would have two batteries. As one battery powered the car, the other would get charged up from power generated by the turning wheels.

I said that is possible but in a short time both batteries would drain and need to be recharged by an external power supply. The other guy said "no it wouldn't". He says that the turning wheels would always charge the "other" battery and it would run basically "forever".

He feels that this car could be built but oil companies would crush it's development for obvious reasons.

I have a Biology Degree that included 4 semiesters of of physics. To have his theroy work would mean a complete breakdown of the thermodynamic laws.

What do you think...am I right?


Yes, you are.

If you ignore losses due to inefficiencies, then the Law of Conservation of Energy would say that his idea would work. Unfortunately for him, the world is not that simple and we have to deal with pesky things like friction and electrical resistance, for example, that cause systems to operate at less than 100% efficiency.

Message edited by author 2008-07-17 21:13:29.
07/17/2008 09:13:56 PM · #3
I'm by far no expert (probably even below novice) in the subject but doesn't the alternator in a regular gas powered car do this to it's battery? In my simple mind it is a awesome idea and should work, but again I know very little on the subject.
07/17/2008 09:16:38 PM · #4
Originally posted by kenskid:

Hello,

I had a discussion today with someone.

They said that there is surely a way to build a car that runs completly on battery power. They said it would have two batteries. As one battery powered the car, the other would get charged up from power generated by the turning wheels.

Removing external factors from the system (tyres friction on the road etc.) - If you imagine one battery driving a motor which is connected to a generator which is charging an identical battery, the system will eventually run out out power (neither the motor nor the generator operate at 100% efficiency).
07/17/2008 09:18:00 PM · #5
Yes...the alternator/generator does charge the battery BUT it is using GASOLINE to generate the power to charge the battery ! You will have to fill the car with gas to keep charging the battery !

In my friends system there is NO external supply !

Originally posted by sabphoto:

I'm by far no expert (probably even below novice) in the subject but doesn't the alternator in a regular gas powered car do this to it's battery? In my simple mind it is a awesome idea and should work, but again I know very little on the subject.

07/17/2008 09:19:43 PM · #6
As I read this I was reminded of a project back in the mid 80's that involved just such a concept. I will see if I can find a link but if I remember correctly, yes it can be done and has, to a degree. But it took three batteries and three separate charging systems to insure one was not a drain on the other that could not be recovered. I believe the system was some sort of fan/rotating blade device that was in itself supposed to produce power for a piece of farm equipment. Something like 3 banks of 4 car batteries each comes to mind.

Message edited by author 2008-07-17 21:22:03.
07/17/2008 09:20:20 PM · #7
You are on the same track as me. The batteries will charge each other for a small amount of time. But...eventually ALL of the power will be lost as work, friction and heat.

Originally posted by jhonan:

Originally posted by kenskid:

Hello,


Removing external factors from the system (tyres friction on the road etc.) - If you imagine one battery driving a motor which is connected to a generator which is charging an identical battery, the system will eventually run out out power (neither the motor nor the generator operate at 100% efficiency).

07/17/2008 09:21:31 PM · #8
CEJ...your example is the same as my friends...it is just "different". Send me the info if you can find it.

Originally posted by CEJ:

As I read this I was reminded of a project back in the mid 80's that involved just such a concept. I will see if I can find a link but if I remember correctly, yes it can be done and has. But it took three batteries and three separate charging systems to insure one was not a drain on the other that could not be recovered. I believe the system was some sort of fan/rotating blade device that was in itself supposed to produce power for a piece of farm equipment. Something like 3 banks of 4 car batteries each comes to mind.

07/17/2008 09:22:51 PM · #9
looking...
07/17/2008 09:32:57 PM · #10
There have been hundreds, if not thousands of folks who, over the last couple centuries, have claimed to have invented a perpetual motion device, which is what the "dual battery car" is. As Robert Heinlein opined, TANSTAAFL. There Ain't No Such Thing As A Free Lunch. Ken & Spaz have it right, the inefficiency in the motor & generator alone would doom it, to say nothing of the energy expended *moving* the vehicle.
07/17/2008 09:39:52 PM · #11
While perpetual motion will never work ... there IS such a thing as an all-battery-powered sports car. And at $109,000 it can be yours! :-)

Message edited by author 2008-07-17 21:40:23.
07/17/2008 09:43:25 PM · #12
I hear ya on that beauty ! However, I'm assuming it has to be charged from time to time!

Edit: OIC...220 miles per charge.

Originally posted by dwterry:

While perpetual motion will never work ... there IS such a thing as an all-battery-powered sports car. And at $109,000 it can be yours! :-)


Message edited by author 2008-07-17 21:44:20.
07/17/2008 10:00:20 PM · #13
Sorry this is alittle off topic but your post reminded me of
Who Killed the Electric Car
This was a great documentry if you have not seen it I HIGHLY recomend it!

On topic now, with Battery advances made almost daily now, more efficient electrical delivery systems, and an overall "go green" push from the younger generations. It has to happen sooner then later. There will be someone who makes "THE INVENTION" that changes the future. As long as they donĂ¢€™t sell out to the oil/auto basterds!
But I doubt it will be a perpetual motion car. But it is possible that geni/batt combo could extend the range of such vehicles to make them more efficient.
07/17/2008 10:02:00 PM · #14
Originally posted by DarkRider:

...But it is possible that geni/batt combo could extend the range of such vehicles to make them more efficient.


Already been done. It's called "regenerative braking" and it's used on pretty much all of today's hybrid vehicles.
07/17/2008 10:21:57 PM · #15
Yes but doesn't the regenerative braking simply "capture" the wasted energy used in the braking process and convert it back to usable (kinetic) energy? If so, in a closed system (with no external power) the car will eventually have to be "refuled".

Originally posted by kirbic:

Originally posted by DarkRider:

...But it is possible that geni/batt combo could extend the range of such vehicles to make them more efficient.


Already been done. It's called "regenerative braking" and it's used on pretty much all of today's hybrid vehicles.


Message edited by author 2008-07-17 22:28:06.
07/17/2008 10:32:26 PM · #16
There is no 100% efficient system. Losses to heat and friction occur in both the charging and motoring process.

No battery is 100% efficient, no motor, no generator. So the system would rather quickly run down. Worse than just the battery and motor alone, because there is the load of the alternator charging the other battery. If a battery could drive a motor to charge another battery, we could build power plants much more simply.

All the old stories of the oil companies quashing the 200 mpg Lincoln Continental are just old stories. Nothing more. Right about now GM and Ford would sell their first born to have such great technology. Before the Japanese invasion into the auto market, it was popular to believe that GM was in bed with the oil companies. With its stock at the lowest levels since the 1950's, I don't think that GM is that loyal to big oil anymore.
07/17/2008 10:42:10 PM · #17
Originally posted by kenskid:

Yes but doesn't the regenerative braking simply "capture" the wasted energy used in the braking process and convert it back to usable (kinetic) energy? If so, in a closed system (with no external power) the car will eventually have to be "refuled".

Originally posted by kirbic:

Originally posted by DarkRider:

...But it is possible that geni/batt combo could extend the range of such vehicles to make them more efficient.


Already been done. It's called "regenerative braking" and it's used on pretty much all of today's hybrid vehicles.

Yes, hybrids use regenerative braking to capture "wasted" energy of motion -- where you are coasting or braking and not applying power -- to (partially) recharge the battery. However, unless you are driving on the M.C. Escher Thruway where you are always going downhill, you have to expend more energy than is recaptured getting to the top of the hill in the first place.

Having two battery packs -- one powering the vehicle and one recharging -- is realy no different than having one battery which can be recharged on the fly. Now, having exchangable batteries, so you can drive around with one while the other charges at home, would make sense if they can get the weight down under several hundred pounds.

BTW: I think I heard that Toyota is going to put solar cells on the roof of the Prius, so the battery can recharge while parked at work ...
07/17/2008 10:52:16 PM · #18
#1
It wont work, you are right. Dont worry about explaining conservation of energy to him though, I have tried that several times when talking to people about perpetual motion machines, the explanation changes nothing.

#2
Ask him why there needs to be two batteries.

His answer should be interesting. And once you quickly remind him what an alternator does, and why we don\'t have 2 batteries in the cars we currently drive, he will understand that has no clue about how cars currently work, and that he should seriously reconsider his design of the car of the future.

another big loss
the drag from airflow around the car, to make it worse, the loss increases exponentially with speed, not linearly.
-- a 10% increase in speed, results in a 19% increase in drag., this is why we hear people say there is so much to be gained by driving 5mph below the speed limit instead of always driving 5mph over the speed limit when you are doing 55 to 80 mph. those losses get very high at 80mph.
07/17/2008 11:23:22 PM · #19
Yup, that drag can be a buggar bear to overcome. Check out this video.

While doing the deed the driver will tell you that it takes 270 hp to do the first 155 mph, but 730 hp MORE to attain 255 mph. Lots of air resistance, plus at those speeds centrifugal forces on the rotating portions of the vehicle reach their limits. Some of this actually helps as the tires gain quite a bit of height at speed helping the gear ratios a bit. But as the driver said, at 350 mph, the tires go in 15 minutes! But that's alright. It runs out of gas in 12 minutes at that speed! I would expect the speed of the pistons in the cylinders would be approaching speeds that would preclude proper lubrication too.
07/17/2008 11:31:33 PM · #20
Originally posted by ambaker:

...All the old stories of the oil companies quashing the 200 mpg Lincoln Continental are just old stories. Nothing more.


I don't get 200mpg, but

I have gotten 42mpg on a 30 minute stretch of the Natchez Trace in Mississippi in my 11 year old 97 Buick Park Avenue Ultra. Not quite 200mpg, but good for a big older car. The transmission in the Park Avenue's decouple more when coasting than most other cars that I have seen. The gear ratio in the Ultra model is shifted more for touring, so it lets me run at a lower rpm on the highway, I keep my tires at max pressure given on the sidewalls. MPG in town is still bad though at about 20mpg.

one of the biggest things we can change as a nation is maintain our tire pressures better. I see so many tires with low pressure.

"The Environmental Protection Agency says that cars driven on tires with lower air pressure than specified can cost up to 3 percent in fuel efficiency. " //www.ehow.com/video_2118573_better-mpg-properly-inflated-tires.html

54% of cars driven in the US have low tire pressure,(not sure what they defined as low)

Under-inflated tires can lower fuel efficiency by approximately 1.4 percent for every 1 psi drop in pressure of all four tires.
//en.wikipedia.org/wiki/Hypermiler

in 2006 there were 250,851,833 vehicles on the road, If 54% of these passenger vehicles have low pressure, that gives us 135,459,989 cars on the road wasting gas needlessly.

another stat: our vehicles traveled 2.3trillion miles in 2001, proper tire pressure would add up to a lot of savings with minimal work. ROI should be high.
//www.bts.gov/publications/highlights_of_the_2001_national_household_travel_survey/html/section_02.html
07/17/2008 11:38:35 PM · #21
Sweet thread going here...thanks for the info.
07/17/2008 11:39:09 PM · #22
Originally posted by fir3bird:

Yup, that drag can be a buggar bear to overcome. Check out this video.

While doing the deed the driver will tell you that it takes 270 hp to do the first 155 mph, but 730 hp MORE to attain 255 mph. Lots of air resistance, plus at those speeds centrifugal forces on the rotating portions of the vehicle reach their limits. Some of this actually helps as the tires gain quite a bit of height at speed helping the gear ratios a bit. But as the driver said, at 350 mph, the tires go in 15 minutes! But that's alright. It runs out of gas in 12 minutes at that speed! I would expect the speed of the pistons in the cylinders would be approaching speeds that would preclude proper lubrication too.

The piston-driven Goldenrod reached a speed of 409.277 MPH in 1965. A real pain to parallel-park though ...
07/18/2008 09:13:55 AM · #23
I travel the Lake Pontchartrain Causeway several times a week...(24 miles one way). The onboard "computer" that calcs MPG shows that at 65mph I get 17-19 miles per gallon. When I drive at 55 I get 20-24 miles per gallon !

I say 17-19 and 20-24 b/c the readout varies during the drive.

Originally posted by jrhendri:

Originally posted by ambaker:

...All the old stories of the oil companies quashing the 200 mpg Lincoln Continental are just old stories. Nothing more.


I don't get 200mpg, but

I have gotten 42mpg on a 30 minute stretch of the Natchez Trace in Mississippi in my 11 year old 97 Buick Park Avenue Ultra. Not quite 200mpg, but good for a big older car. The transmission in the Park Avenue's decouple more when coasting than most other cars that I have seen. The gear ratio in the Ultra model is shifted more for touring, so it lets me run at a lower rpm on the highway, I keep my tires at max pressure given on the sidewalls. MPG in town is still bad though at about 20mpg.

one of the biggest things we can change as a nation is maintain our tire pressures better. I see so many tires with low pressure.

"The Environmental Protection Agency says that cars driven on tires with lower air pressure than specified can cost up to 3 percent in fuel efficiency. " //www.ehow.com/video_2118573_better-mpg-properly-inflated-tires.html

54% of cars driven in the US have low tire pressure,(not sure what they defined as low)

Under-inflated tires can lower fuel efficiency by approximately 1.4 percent for every 1 psi drop in pressure of all four tires.
//en.wikipedia.org/wiki/Hypermiler

in 2006 there were 250,851,833 vehicles on the road, If 54% of these passenger vehicles have low pressure, that gives us 135,459,989 cars on the road wasting gas needlessly.

another stat: our vehicles traveled 2.3trillion miles in 2001, proper tire pressure would add up to a lot of savings with minimal work. ROI should be high.
//www.bts.gov/publications/highlights_of_the_2001_national_household_travel_survey/html/section_02.html
07/18/2008 09:19:18 AM · #24
In theory is everything ran at 100% and there was no loss of power from friction and whatnot then yes, he would be right. However in the real world he is dead wrong =)

07/18/2008 09:30:13 AM · #25
Originally posted by GeneralE:

.... unless you are driving on the M.C. Escher Thruway ...


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