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motors as generators

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jasto

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i was wondering how to connect two motors so that one can rotate the other to generate current that can charge a small battery. is this possible and can i use a phone battery?
 
It's possible, but why would you want to go through such complication just to charge a battery? Can't you use to power that drives the motor to charge the battery?
 
It's possible, but why would you want to go through such complication just to charge a battery?
Then you can use the battery to run the first motor, which in turn charges the battery - simple!
 
Then you can use the battery to run the first motor, which in turn charges the battery - simple!

Sorry, I've tried that. Not that simple :D

It would depend on what type of motors you are using--AC or DC. You can probably just use a bridge rectifier to convert the output to DC, to charge your battery. However, if you are hoping that one motor can run off the battery that you are charging, and at the same time turn your "charging motor" (as dougy83 suggests), you are talking perpetual motion. As far as I know, it's still "impossible," but I suppose it is still worth some experimentation. I'm still not sure WHY perpetual motion is considered "impossible"... :D
Der Strom
 
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Without thinking deeply about it, I would make the statement that perpetual motion is possible in a system without losses - e.g. an object spinning in a perfect vacuum, devoid of any particles or fields. Anything less than lossless will eventually stop without some external energy input.
 
Without thinking deeply about it, I would make the statement that perpetual motion is possible in a system without losses - e.g. an object spinning in a perfect vacuum, devoid of any particles or fields. Anything less than lossless will eventually stop without some external energy input.

You would also have to take into account losses caused by mechanical friction, which you cannot eliminate. The closest to perpetual motion that I have seen to this day are "Air Cars." Basically, compressed air "powers" the car, and at the same time spins a generator. The generator powers the on-board air compressor that compresses the air for another cycle.
I suppose perpetual motion may be possible if you generate more power than is necessary in order to account for friction, though the friction will also increase. As I said, it's definitely worth the experimentation.
Der Strom
 
You would also have to take into account losses caused by mechanical friction, which you cannot eliminate.

There won't be mechanical friction in a perfect vacuum devoid of particles & fields - which is likely a bit hard to find in this universe. There is also not much use in a perpetually spinning/moving solid object.

The closest to perpetual motion that I have seen to this day are "Air Cars." Basically, compressed air "powers" the car, and at the same time spins a generator. The generator powers the on-board air compressor that compresses the air for another cycle.

I can imagine that being quite inefficient. Firstly, the moving air has friction losses with its containing ducting & nozzles, as do all moving joints, bearing, etc. The generator and all wiring has conduction losses.

I suppose perpetual motion may be possible if you generate more power than is necessary in order to account for friction, though the friction will also increase.
I'm not sure I understand what you're saying; but I think we have different definitions of what perpetual motion is - it is not running a machine from a power source, or desk fan plugged into a power socket would be a perpetual machine, for example.

As I said, it's definitely worth the experimentation.
Go for your life.
 
The motion of the planets around the sun could be considered perpetual motion (at least until the sun explodes eons from now) since there is no friction to slow them down. But any motion that produces friction or other energy losses will eventually stop without an input of external energy. Thus practical perpetual motion here on earth is impossible.
 
There won't be mechanical friction in a perfect vacuum devoid of particles & fields - which is likely a bit hard to find in this universe. There is also not much use in a perpetually spinning/moving solid object.

Even in a perfect vacuum devoid of particles and fields, any machine with moving parts will have mechanical friction. If you have a desk fan and put it in a complete vacuum without ANY air particles or anything, there will still be friction within the motor (one the armature, for example).

I can imagine that being quite inefficient. Firstly, the moving air has friction losses with its containing ducting & nozzles, as do all moving joints, bearing, etc. The generator and all wiring has conduction losses.

It may be inefficient, but the prototypes have actually been built and tested. Here is a wikipedia article on the air cars I am talking about. There have been prototypes since the 1920s, but they seem to be getting better and better over time. The writer Jules Verne predicted the use of automobiles that run on air even during his lifetime (1828-1905), so I suppose that may be when the experimentation actually began.

I'm not sure I understand what you're saying; but I think we have different definitions of what perpetual motion is - it is not running a machine from a power source, or desk fan plugged into a power socket would be a perpetual machine, for example.

Sorry, now I don't understand what you are saying. :D When I say "perpetual motion," I mean self-sustaining mechanical energy--in this example, one motor running a generator, which in turn is powering the motor.

Go for your life.

You never know--Anyone could suddenly have an epiphany about how to make perpetual motion possible (Think Doc from "Back to the Future" :D ).

Der Strom
 
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You never know--Anyone could suddenly have an epiphany about how to make perpetual motion possible (Think Doc from "Back to the Future" :D ).

Der Strom
First you would need to repeal one of the fundamental laws of physics on the conversation of energy. To paraphrase "There's no such thing as a free lunch".

As far as "Doc" goes, fictional characters can obviously do anything they want, not being bound by the laws of the universe.
 
First you would need to repeal one of the fundamental laws of physics on the conversation of energy. To paraphrase "There's no such thing as a free lunch".

As far as "Doc" goes, fictional characters can obviously do anything they want, not being bound by the laws of the universe.

I understand the law of the conservation of energy. I have just never quite understood exactly WHY.
As for "Doc," it was just a JOKE :D

Der Strom
 
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I understand the law of the conservation of energy. I have just never quite understood exactly WHY.
I don't believe there is a particular reason (at least that we know of) for that empirical law, or any other law of physics. It just the way the universe operates. It may be that a universe designed otherwise would not be stable.
 
I don't believe there is a particular reason (at least that we know of) for that empirical law, or any other law of physics. It just the way the universe operates. It may be that a universe designed otherwise would not be stable.

That is understandable and may very well be true. However, it is my nature to wonder, if I don't know WHY a law is "true," if it would be possible to find a situation that breaks that law. :D
You know what they say--Rules are made to be broken :D
 
That is understandable and may very well be true. However, it is my nature to wonder, if I don't know WHY a law is "true," if it would be possible to find a situation that breaks that law. :D
You know what they say--Rules are made to be broken :D
True. But breaking laws may get you in trouble.;)
 
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this is cause i want to form a circuit that does not relay on external power but one that relay on itself.if it is possible, please assist on the connections involved.if possible a diagram would assist a lot.
 
then what modifications are needed for the circuit to function.please note i do not want to use an external power source but a battery with some charge which will rotate the first motor and the second motor rotated by first motor charge the same battery
 
then what modifications are needed for the circuit to function.please note i do not want to use an external power source but a battery with some charge which will rotate the first motor and the second motor rotated by first motor charge the same battery

Won't work.
Did you know that the batteries when are being charged get hotter? Heat = Energy Loss. That + friction + hysteresis loss you may have on any magnet means you waste more energy that you produce.
Use solar panels if you dont want to plug your circuit to any battery.
 
then what modifications are needed for the circuit to function.please note i do not want to use an external power source but a battery with some charge which will rotate the first motor and the second motor rotated by first motor charge the same battery
You haven't been paying attention to our posts. In physics there's no such thing as a free lunch (or perpetual motion).
 
You never know--Anyone could suddenly have an epiphany about how to make perpetual motion possible (Think Doc from "Back to the Future" :D ).

i want to know how the doc's plutonium reactor made 1.21 Gwatts without a steam turbine.

....

'perpetual motion' might well suffer a misnomer problem. 'over-unity'? not possible.

perpetual motion? well, we have it... it's called a water-fall. with one cubic metre of water weighing in at a metric tonne, there's a lot of push available.
china has a +18Gwatt waterwheel installation running at the moment... yes the environmental impact has been huge, but it doesn't always have to be... and one might be tempted to compare the fallout of dams with nuclear waste which stays bad for 1000's of years.
i know it's kind of site-specific, but tidal power is basically 'free energy' which uses the movement of celestial bodies. twice a day, more potential energy than you could ever hope to even use, let alone harness just ripples across the planet.

but back to more practical movements. i was just recently looking at some sealed - pumped-water-storage designs. excess power during off-peak times is diverted to the lifting of subterranean weights via a water-pump. during peak energy use hours, the pump becomes a generator as the weight is pulled by gravity and pushes water through the closed system.
there are losses of course, but much less than having to drop your powerplant below optimum efficiency during off-peak hours.
i've heard that all those windmills in the north-sea have their power diverted to lighting up the highway between amsterdam and paris.

actually, i've heard that the TGV train drivers had a competition going to sea who could nail the most efficient coast into paris. this would basically involve a train traveling at +300Km/hour letting go of the throttle and just coasting to a full stop at the station with the least amount of brake use possible. the train's 3phase motors seamlessly become generators when the train is coasting and essentially pump power back into the grid as they slow down.
also of note is the montréal metro system. many of the stations feature inclines so that the trains must go a bit uphill just before approaching the platform, and downhill as they leave. much of the braking performed by using the motors as generators. i've heard that the schedule is timed so that, ideally, the braking of trains coming into stations will provide a boost to the power of trains which are simultaneously leaving stations. . . with that, current-chopper traction motors, and the rubber-tires,,,, music to my ears : )

..oh. so yeah. you can use motors as generators. and headphones as microphones, and cameras as projectors... just depends on sink and source, which way the power is compelled to move (if there is any)
 
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