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Discussion Starter #41
I did the math and in a perfect world you will need one horsepower for every 62 amps at 12v, or 31 amps at 24v. Keep in mind the belt drive and alternator together may be as low as about 65% efficient. If you're wanting to run close to idle for noise mitigation(a good idea IMO), you might need a bigger engine than you realize. Also, most vehicles' alternators are set to spin three times the engine speed(so typically ~6000rpm). I think this would be a good baseline because too slow and you lose a lot of efficiency--too fast and you will wear out the alternator prematurely. You also may want to look at the work of some of these "green energy" guys. You can gain a lot of efficiency by converting one into a permanent magnet alternator. The catch is it has to spin at the same RPM's all the time--which should be doable with a good governor. The biggest benefit would be it would not need a battery to power the exciter coils in order for it to work. You could even use it to charge a dead battery, or power some equipment all by itself.

crash262: I just put a Honda GC-160 5.0hp on a little longtail mud motor and I can attest it is not extremely quiet. The muffler is a joke. The insides jiggle around so much they literally wore holes through the outside walls. It does not have a camshaft; the "overhead cam" is a plastic--yes, plastic--gear with some funky cam lobes molded into it and it is timed by a rubber belt that runs in oil rather than a chain. I just built it and cannot attest to its longevity, but I can say it is unbelievably lightweight and only uses one-half quart of oil. I'm going to run it hard and when/if it breaks I will switch it out with a 6.5 Predator.

Good Info bud. Yeah the "green energy" or "prepper" guys have some good info on building one of these.
 

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They make alternators that can put out 140 amps at idle. You can also mount them so that a B&S engine can run them .
 

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Discussion Starter #45
They make alternators that can put out 140 amps at idle. You can also mount them so that a B&S engine can run them .
Yeah I would like to try to find the most efficient low speed one I can... But I want to keep the cost down.... so many ideas! this is gonna be cool If I can get mine to work like I want it to.
 

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Tell you what Skippy. Go to a junk yard and look at the trucks around 1999-2000 or so. When you find one look in the glove compartment and there is a SPID label (they're white) with a bunch of codes on them. The one to look for is KG3. The worst you'll find is one rated for 130 amps at idle.
 

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How about this for a thought. I have a 3/4 h.p. electric motor that was on a old meet grinder. It operates at 2150 rpm. My 1000 watt generator will run it on Eco mode. I understand its not 12 volt and a generator will still b needed but the generator is quite and so is the electric motor. This would eliminate the 2 2000 watt generators and the 3 converters I currently run. I'm probably not going to try it but in theory should work.
 

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How about this for a thought. I have a 3/4 h.p. electric motor that was on a old meet grinder. It operates at 2150 rpm. My 1000 watt generator will run it on Eco mode. I understand its not 12 volt and a generator will still b needed but the generator is quite and so is the electric motor. This would eliminate the 2 2000 watt generators and the 3 converters I currently run. I'm probably not going to try it but in theory should work.
If you do try it just take an amp clamp meter and when play with pulley sizes make sure if there is a data plate on the motor for RLA ( run load amps) or FLA (Full load amps) that the motor amp draw stays at about 80% -85% of rated load to keep motor from burning up or being overloaded.
 

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Thanks garp. Probably not going to try until I have issues with my current set up. I have a small forchen in my current set up and it works. However I wish I would of tried this years ago its crossed my mind more then once. In fact I thought about how the wind mill works or a turbine at the power plant and using the water to spun a alternator. Crazy rite wouldn't keep up but might keep you on the water a bit longer lol
 

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How about this for a thought. I have a 3/4 h.p. electric motor that was on a old meet grinder. It operates at 2150 rpm. My 1000 watt generator will run it on Eco mode. I understand its not 12 volt and a generator will still b needed but the generator is quite and so is the electric motor. This would eliminate the 2 2000 watt generators and the 3 converters I currently run. I'm probably not going to try it but in theory should work.
At 100% efficiency, a 3/4 hp motor would generate 559.5 watts.

Thanks whiteriverrambo, but it's not that hard. One horsepower equals 746 watts. The engine will need to be at least one hp at given rpm for every 746 watts generated in a perfect world. Just remember, nothing is ever 100 percent efficient. I think figuring 65% would give a reasonable margin for error.
 

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I'm having a hard time finding the info on how to convert a chevy alternator into a Permanent Magnet Alternator. Watched a ton of terrible youtube videos with no useful information today.
 

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I'm having a hard time finding the info on how to convert a chevy alternator into a Permanent Magnet Alternator. Watched a ton of terrible youtube videos with no useful information today.
Make or buy one of these...
$(KGrHqJHJEcFBfObtLlnBQc0N1MQ-g~~60_3.JPG

I notice there are now several people selling permanent magnet alternators on ebay. And many have used dc motors from treadmills as generators. The thing is, you need the alternator/generator to put out the right voltage at the rpm's you intend to run it, or have extra electronics to convert the voltage. That's why automobile alternators don't use permanent magnets. By varying the strength of the electromagnet, it can automatically hold the voltage where it needs to be regardless of the rpm's. But...it needs electricity to make electricity.
 

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I'm a 4th year electrical apprentice that's ready to take my journeymen test....
Looks great and love the idea. The only thing I would add is a sensor and contact to disconnect power to the batteries when they are fully charged and reconnect power to charge them when they aren't. Just worried about cooking batteries. :pop:
 

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lots of good ideas and think this could be an alternative to generators for sure if you use a fan on your boat and leds, a lot of the other light setups use a lot more juice.
 

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Discussion Starter #59
Tell you what Skippy. Go to a junk yard and look at the trucks around 1999-2000 or so. When you find one look in the glove compartment and there is a SPID label (they're white) with a bunch of codes on them. The one to look for is KG3. The worst you'll find is one rated for 130 amps at idle.
OK man thanks, we have a Pull a part here that I may hit up .. and like 20 other junk yards lol.
 

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How about this use a vertical shaft lawn mower engine and mount the alternator with the pully down. Seems it would b much safer and easier to build. And you can get a small push mower for free on Craig's list.
 
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