Motor/Generator

[Kid at Heart]

Slightly off topic. Has anyone tried building any of the motor/generators that I've seen advertised and on YouTube? Since they use the power of permanent magnets, they are NOT perpetual motion devices. I've seen some videos that seem to go back over a decade and nothing seems to be in production. And I've seen nothing that gives any kind of performance specs for any of these machines.

Just curious. I was thinking about building one...or two... or more. If I could get a continuous production of even a couple hundred watts, that would mean something for my disaster preparedness plans.

David

[Elden DuRand]

David:

I don't want to be the one to rain on your parade but I guess I've been elected.

Motor-generators connected together for the purpose of self generating power have been an idea that emerges from the grave of perpetual motion machines despite wooden stakes being driven into their armatures.

You simply cannot get something from nothing or get more out of a machine than you put into it.

Now, if I misunderstood you, I apologize but if it sounds too good to be true, it most likely is.

Take care - Elden
http://www.oldengine.org/members/durand

[K D Redd]

A friend of mine has a motor-generator from a motor home he once had. It's input voltage is 12 Volts DC. It's output voltage is 120 Volt AC. It output was about 5 amps AC but put about a 55 to 60 amp load on a 12 volt battery. It was set-up in the motor home on one receptacle to power a small load when you were driving down the road but you did not want to start the main generator. He would be willing to sell it if you are interested. PM me if you are.

Kent

[BTPost]

Motor/Generators went out of favor, back in the 80s, as Inverter, and Solid State Technology became much cheaper. Silicon is MUCH cheaper than Copper, and Steel... and actually MUCH more efficient...

[armandh]

keep a tight grip on your wallet
there is no free lunch
or if there is they want to "manage" your retirement savings.

a fool and his money are some party!

[Kid at Heart]

Well, I was hoping that some kind of use of permanent magnets would get out of the realm of perpetual motion. LOL. One of the designs I was thinking of, turns out to be a generator using permanent magnets and needs to be powered by a windmill.

So, thanks for the thoughts. Looking at youtube, it seems like some people out there are designing some interesting things with magnets. I just wished I knew how some of it worked.

Regards and thanks again.

David

[J.B. Castagnos]

If you spin the motor and it doesn't stop, you don't need the generator, if you spin the generator and it doesn't stop, you don't need the motor. If they both stop you have friction and won't keep running if coupled together.

[KEB]

Originally Posted by Kid at Heart

Well, I was hoping that some kind of use of permanent magnets would get out of the realm of perpetual motion. LOL. One of the designs I was thinking of, turns out to be a generator using permanent magnets and needs to be powered by a windmill.

So, thanks for the thoughts. Looking at youtube, it seems like some people out there are designing some interesting things with magnets. I just wished I knew how some of it worked.

Regards and thanks again.

David

I don't know where people get the idea that you can get energy out of permanent magnets. The amount of energy stored in the magnetic field is trivial, and you'd have to somehow de-magnetize the magnet to recover the energy that created the field originally.

You can get energy out of a coil of wire passing through the magnetic field (which is exactly what permanent magnet generators do), but you're converting the kinetic energy required to move the coil through the magnetic field into the electrical energy you get out of the coil...you're NOT recovering energy from the permanent magnet. Conversely, you can convert electrical energy into kinetic energy by passing current through a coil of wire immersed in a magnetic field, which makes the coil move.

Anyone who thinks they can get more energy out of a system than they put into it is either a charlatan or doesn't understand what they're doing well enough to realize where the actual energy transfers are occurring.

Keith

[DLeach]

I've heard over and over again that permanent magnets can do no real work. Guess I better look for a scoop at the local hardware store to pick nails out of the bin since permanent magnets can do no real work.

[BTPost]

I think the ISSUE, here is, in the Electrical Generation Instance, Permanent Magnets do NOT provide the Working Force, that creates the Current Flow thru the Stator Windings. So in this Instance, They do NOT contribute to the Work.... Just Saying....

[KEB]

Originally Posted by DLeach

I've heard over and over again that permanent magnets can do no real work. Guess I better look for a scoop at the local hardware store to pick nails out of the bin since permanent magnets can do no real work.

Lets try a little thought experiment here. Suppose I have a magnet strong enough to pick up a nail at some distance suspended at this distance above a nail held in my fingers. When I release the nail, it is attracted to the magnet, and jumps up to the bottom of the magnet. Guess what...I've added potential energy to the nail (pulled it up against gravity), or done "work" as defined in physics. So where did the energy to do that work come from...why from the energy stored in the magnetic field of the magnet, of course.

And where did the energy stored in the field come from? From what ever source was used to originally create the magnetic field, generally an electric current used to magnetize the magnet in the first place.

So now I've converted some of the energy originally stored in the magnetic field to potential energy stored in the nail So what if I attract another nail...same thing, some additional portion of the energy stored in the magnetic field is now converted to potential energy stored in the nail. So how many nails does it take until all the available energy in the magnetic field has been converted to potential energy in the nails....as it turns out, not all that many.

Now what happens when I remove the nails? It takes energy to pull the nails away from the magnetic, which is converted back to energy stored in the magnetic field, minus the losses due to eddy currents in the nails as they move through the magnetic field.

So lets try to construct a machine that uses permanent magnets to "make" energy. If i connected each nail in the example above to a pulley system, I could create rotary motion (kinetic energy) as each nail moves to the magnet. So far so good, right, but what happens when we've attracted as many nails as the magnet can? The machine stops, and the only way we can attract more nails is to remove some of them that are already attached to the magnet. So guess what, it takes energy from some external source to do that, plus we've got the inherent eddy current losses due to moving a conductor through the magnetic field.

If you want to get an idea of how much energy is stored in the magnetic field of a real magnet, look at how much energy a magnet charger uses to re-charge a large magneto magnet. Maybe a few hundred watt-seconds? That's enough energy to run a 100 watt bulb for a few seconds.

The best you can ever hope to do is to recover some portion of the energy originally used to create the magnet, which, as we've seen, is not very much, and at that point, the magnet you started out with is no longer a magnet.

Conservation of energy works...except in a nuclear reaction, energy can be neither created nor destroyed, it can only change form. Even in a nuclear reaction, the conversion is between matter and energy.

Keith

[Seafarer12]

I worked in an old plant that used MG sets for control power but they were far from efficient. Now a days we use ups's to supply control power. I can't think of much use for mg sets anymore. Considering motors and generators produce heat, flux losses, eddy currents, and have friction you would have to bend some laws of nature somewhere.

Talking about magnetic fields and power generation. One of our generators uses about 80kw for its field to produce 150mw. Its a pretty small amount compared to output.

[Bloc911]

I have also been looking at those types of generators. They are calling them PMA's (Permanent Magnet Alternators) or PMG's (Perm. Mag. Generator). They are basically the same as used on most motorcycles but made with larger automotive style alternator casings. The rotor's electromag. core gets replaces with a perm. mag. and when turned by a motor, wind turbine... they generate electricity. After a lot of research, I like the one produced by Missouri Wind and Solar. They explain why and how they work and have several tutorial videos on how to make them yourself. The prices for the models they produce seem good compared to some of the other companies i have checked out. They can be powered by a variety of drives: wind, motor, water... and there a lots of sites and videos all using some variation of this same tech using every thing from old brake rotors, ceiling fan motors, tread mill motors, and a few that were trying different AC and DC motors. They re wrap the coils with small diameter wire and figure out how to add magnets to the rotor and start spinning them to see how much power they get. Some do good, others not so hot. I have checked around 15 diff makers of PMA's and they come in a wide variety of designs and outputs as well as prices. check around and you should be able to find some that suit you needs, or even be able to find good how to videos on how to take what you have and make one or more. Hope this helps.

Another note about PMA's to watch out for is whats called "coging". Like the teeth on gears when they rotate there is a perceptible vibration produced form the friction of the rotation. Some Pma's have a problem with this. Although they will produce power they have a harder time starting in wind applications, and are often subject to increased bearing wear. As far as I can tell to negate the coging effect there needs to be an odd number of either magnets if multiple are used on the rotor. If a single large ring style magnet is used then it not as big of an issue. However the larger ring style magnets typically produce far less output than multiple individual magnets. The only other issue I have come across is heat. They will burn out if they get to hot just like any other motor or generator. Even in wind driven applications you need to make sure they will get adequate cooling. I like the auto style PMA's for this reason, the same fan that you find on them to cool them while in an engine bay can still be used on them when converted to a PMA for cooling. After that it all comes down to how you arr going to connect it. Auto style PMA's can generate wither AC or DC just not both at the same time. The electricity produce is wild and you will needs to feed it in through a bridge rectifier and then in to you choice of inverter or conditioner components afterwards, as they will depend on your PMA's output type (AC or DC). Again, I hope this helps.

[mikey ny]

I also belong to a forum call otherpower.com. Mostly about building wind turbine (generators) from scratch. An old Volvo front disk brake hub some magnets, copper wire, resin and of course, wind. You now have free energy as long as the wind blows. Great site, kind of like this one, very educational, almost always friendly , occasionally snobby, and quite entertaining at times. Check it out.

[LiverpoolDave]

Hi from over the pond!
If your referring to the types that have a ring of set magnets opposing fields driving around a rotor-shaft without any other power input-drive, they do work & fascinating they look a swell, but as always you get nothing for nothing.
The quite expensive Neodymium Magnets wear down in a relatively short time (in Weeks) have read until it comes to a standstill. Using Permanent Magnets within P.M.G.'s in a Wind or Water Turbine is (potentially) far more rewarding as their Magnetism can last for Years-Decade & still make useful power. Some of the lower rpm ones from China, they always are made there due to Mongolian Magnet Mines & virtual slave labour wages, can make quite good power even at 150-250 rpm which is realistic in fair-good wind speeds & with decent profile blades.

[armandh]

here is how it works
http://i0.kym-cdn.com/photos/images/...5770302993.jpg
and more
http://start.funmoods.com/results.ph...l&f=4&start=41