Power Generator using DC Motor and Alternator

To all, :thinkerg:

I was brainstorming the other day when an idea came to mind. Why can't we use a starter (which I think is also known as a DC motor) coupled with an alternator to generate power for a home once jump started with a car battery?

Some additional thoughts are, if a motor takes less power than the alternator generates at the same rpm, wouldn't the motor keep running even after it is jumped and disconnected from the battery? How about if multiple alternators are running on the same belt/pulley, the first alternator to keep the motor running, and the others connected in parallel providing alternating current?

Thanks in Advance
Greg

Two problems;

1- a starter is only rated for intermittent high-draw use. Anything more than about 30 seconds and you'll fry the starter

2- what you are proposing is perpetual motion. The energy created by the alternator will ALWAYS be less than what the starter takes.

What if I use a geared motor?

You still will be far from 100% efficient, or more if you want a perpetual motion system that can actually provide power. 100% efficient would mean you would generate just enough power to run the motor. Sorry, it's not going to happen. I'm guessing here, but the alternator is probably only about 65% efficient and a DC motor (geared or not) is probably around 50% efficient. If there is any heat generated when in use, the unit is not very efficient.

-Rod

Aside from the perpetual motion points (which are correct) if you need to produce AC power from a car battery, then electrical inverters are quite common and cheap.

Thanks for the replies.

What if we change it up a bit. A permanent magnet motor and alternator such as:

Motor:
http://cgi.ebay.com/Permanent-Magnet-HD-12V-DC-Motor-Wind-Hobby-Karts-RC_W0QQitemZ110272214397QQcmdZViewItem?hash=item11 0272214397

Alternator:
http://cgi.ebay.com/HighAmp-PMA-Permanent-Magnet-Alternator-Generator-SC12F_W0QQitemZ110273875104QQcmdZViewItem?hash=ite m110273875104

If this set of parts don't cut it, what combination of parts will generate ~4000 watts without a permanent external power source (just to jump start it and let it run.)

Greg

Thanks for the replies.

What if we change it up a bit. A permanent magnet motor and alternator such as:

Motor:
http://cgi.ebay.com/Permanent-Magnet-HD-12V-DC-Motor-Wind-Hobby-Karts-RC_W0QQitemZ110272214397QQcmdZViewItem?hash=item11 0272214397

Alternator:
http://cgi.ebay.com/HighAmp-PMA-Permanent-Magnet-Alternator-Generator-SC12F_W0QQitemZ110273875104QQcmdZViewItem?hash=ite m110273875104

If this set of parts don't cut it, what combination of parts will generate ~4000 watts without a permanent external power source (just to jump start it and let it run.)

Greg

Nothing can provide that.:headshake

If you want power out (like electricity), then you have to provide more shaft power in than you get electrical power out. The more efficient your generator, the less you will lose, but you will always lose a certain amount.

It will ALWAYS require more energy in than you get out. There is no such thing as perpetual motion.

Let's say it takes 60 amps to make a 3 hp motor spin. Now attach a 60 amp alternator to it. Just making 60 amps will take all that 3 hp, which means your motor is now drawing 150-200 amps, but you're only producing 60 amps to replace it.

I don't care how efficient you make things, you can't have perpetual motion. Every step of the way, you're losing energy to friction, heat, noise, etc.

I was just wondering what had happened to a post I had put on here yesterday. It appears to have vanished.

Gammaray1965

I had posted a comment here yesterday, and it seems to have vanished. Could someone tell me why.

Thanks

Gammaray1965

As it states in the reason for deletion area under where your thread was, it was deleted because it was an old thread (and old website) for a free-energy website. As your first post, that could have been seen as spam or an attempt at free advertising which is against forum guidelines. Additionally, the website you posted did not appear to have any merit.

-Rod

Shorod is right. I did it :) ... although I'm not sure he can see the reason for deleting since he's not a mod

Old threads shouldn't be ressurected, and I don't have any tolerance for links to websites that violate the laws of physics :)

Shorod is right. I did it :) ... although I'm not sure he can see the reason for deleting since he's not a mod


Ahhh, I've learned my one thing for the day, I can go home now.

-Rod

so if what greg is purposing is not doable then the car alternator is an item that defys all your laws.

if u were to use a dc motor that spun at 2100rpm under the influence aof a car battery u would be able to run the alternator to the point where the alternator is self sustaining. which means it would provide itsself enough electricity to send back to its field and charge the battery.

this is not perpetual motion eventually the battery will crap out. u are using other energy to maintain motion. this does not defy any laws of physics.

the alternator would most likly not be able to provide any extra electricity so u would have to figure out a way to turn a generator at its needed speed to get any extra electricty

in no way are u getting something from nothing here. u are putting energy in and in time u will run out of energy. but just go pick up another battery.