# Homemade generator



## razorface1986

Hey everyone just theowing it out the but a push lawn mower engine , bondo and bicycle sprockets and a car alternator can be made in to a generator any other ideas out there want more info let me know


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## cedarguy

Are you talking about a DC generator?


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## razorface1986

Ac or dc all u need is a cig lighter and convertor to run either


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## Fossil

My first fiddling with the waterwheel design involved an old alternator. When the 12v light bulb came on you would have thought I discovered Unobtanium or something! If you have stuff lying around it never hurts to play with it.


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## 8thDayStranger

Saw one made with a fan blade and a battery drill. Thought about trying it one day.


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## labotomi

cedarguy said:


> Are you talking about a DC generator?


Technically speaking, all rotational generators produce AC. The AC can then be converted to DC if desired.


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## Tirediron

What?? , segmented armature generators produce DC. most slip ring externaly exited units produce ac that is often converted to dc thru diodes.

OP there are quite a few examples of lawnmowers made into generators on the net, most use a v belt to drive the alternator, while it would work it would not be very efficient. if you needed a noisy way to charge automotuive batteries it would be ok as long as they weren't overly discharged.


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## labotomi

Tirediron said:


> What?? , segmented armature generators produce DC. most slip ring externaly exited units produce ac that is often converted to dc thru diodes.
> 
> OP there are quite a few examples of lawnmowers made into generators on the net, most use a v belt to drive the alternator, while it would work it would not be very efficient. if you needed a noisy way to charge automotuive batteries it would be ok as long as they weren't overly discharged.


In both examples, AC is produced then converted to DC by using commutators in your fist example and diodes in the second. Because it's an AC signal that's converted to DC (via whatever means) you end up with the rippled DC output which is why it's considered "noisy" as you say.


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## cowboyhermit

This is more or less just semantics but there is not actually any AC produced as long as the commutator is functioning, there is the potential for it to be produced. 
Pulsed DC is not AC. 
I think he may have meant audible noise.

I have seen these done and done myself, they tend not to be very efficient but they need not be terrible. If you hook up a 5hp motor to a little alternator you would have to use some serious reduction and idle the motor to get a decent return for fuel, still probably better than running a vehicle to charge a battery bank in an emergency. On the other hand if you are experimenting with wood gas or ethanol, etc, a cheap used motor may be they way to go. Running a traditional generator to charge batteries is not too efficient either.


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## Davarm

Mother Earth News had an article(in 70's or early 80's I think) on making something like what you are talking about. I will pull out my old copies and see if I can find it.


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## Magus

got pictures?

If you add a water pump to that motor, you can pump water too.


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## labotomi

cowboyhermit said:


> This is more or less just semantics but there is not actually any AC produced as long as the commutator is functioning, there is the potential for it to be produced.
> Pulsed DC is not AC.
> I think he may have meant audible noise.


I stated that "technically" only AC is produced in a rotational generator. I will concede that many will incorrectly consider the term generator to encompass the entire device from the motor/turbine or whatever prime mover is used up to the output terminals. But any rotational electricity producing device induces AC into the armature.

AC *IS* what is produced via induction into the armature and there are no exceptions. You only have DC *AFTER *the commutator provides crude rectification to DC. The commutator itself carries AC current, the brushes and bar separation is what causes the polarity swap to convert the AC to a pulsed DC

I'm not saying pulsed DC is AC and you're mistaken if you think that was the justification behind my statement.


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## cowboyhermit

Incorrectly according to what definition? There are several things that are correctly called a generator. 
What does this have to do with the op or the question of whether it is a DC generator?


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## labotomi

cowboyhermit said:


> Incorrectly according to what definition?


Textbooks, trade journals, my professors, course materials and mine.


cowboyhermit said:


> There are several things that are correctly called a generator.


There are several things that are incorrectly called generators as well


cowboyhermit said:


> What does this have to do with the op or the question of whether it is a DC generator?


It was a trivia response to the second post. Tirediron decided to act like I had no idea what I was talking about so I elaborated. Then you interjected your statement about no AC being produced which is incorrect... and here we are.


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## cowboyhermit

If it was just trivia then I am sorry I got involved, was not trying to argue. A DC generator is a device that produces DC electricity, that is a correct definition.
Since we already are discussing it though, the definition of a "rotational generator" would have to be one that excludes homopolar generators that do indeed use rotation, albeit in a different direction.


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## Tirediron

http://www.theepicenter.com/tow082099.html

a link to a set of directions to build a generator as mentioned by OP , just a bit of a warning if you build one of these don't try to charge a flat battery with it, the low power available from a small gas engine won't be enough to spin the alternator fast enough to cool properly at high loads


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## mpguy18

When it comes to this I'm a newb. Is there a relative efficient generator that can be built out of "stuff" (lawn mower morot, alternator, etc) that we woudl have around the property without having to go to the store? Looking to power the well and small items if it was really necessary. Can't afford to buy a generator now, and the plans you google are a bit scarey at best, thrown together crap to get a charge. Am looking to build something that can be functional, relatively efficient and easy to maintian. Or am I off the charts in expectations?


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## labotomi

mpguy18 said:


> When it comes to this I'm a newb. Is there a relative efficient generator that can be built out of "stuff" (lawn mower morot, alternator, etc) that we woudl have around the property without having to go to the store? Looking to power the well and small items if it was really necessary. Can't afford to buy a generator now, and the plans you google are a bit scarey at best, thrown together crap to get a charge. Am looking to build something that can be functional, relatively efficient and easy to maintian. Or am I off the charts in expectations?


See if you can find an old treadmill motor. They're not difficult to convert to generators and can be found for next to nothing on craigslist since you're not looking for the high end treadmills with all the fancy controls.


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## cedarguy

mpguy18 said:


> When it comes to this I'm a newb. Is there a relative efficient generator that can be built out of "stuff" (lawn mower morot, alternator, etc) that we woudl have around the property without having to go to the store? Looking to power the well and small items if it was really necessary. Can't afford to buy a generator now, and the plans you google are a bit scarey at best, thrown together crap to get a charge. Am looking to build something that can be functional, relatively efficient and easy to maintian. Or am I off the charts in expectations?


See if this helps http://theepicenter.com/tow02077.html

Wow these guys are above my head..I just asked if he was referring to a DC gen. because I didnt see a convertor or AC power head in the first post.


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## 8thDayStranger

I've been reading all this and it's very interesting. I have a question and I'm no genius so bear with me. This lawn mower gen is underpowered you say. Is this because of the alternator or the speed of the mower engine? If its the speed, couldn't you put a larger pulley on the mower and smaller on the alternator thus spinning the alternator faster?

Edit: forget the larger pulley. That would keep you at the same speed I think. But a smaller pulley on the alternator would speed it up. Am I correct?


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## cowboyhermit

8thDayStranger said:


> I've been reading all this and it's very interesting. I have a question and I'm no genius so bear with me. This lawn mower gen is underpowered you say. Is this because of the alternator or the speed of the mower engine? If its the speed, couldn't you put a larger pulley on the mower and smaller on the alternator thus spinning the alternator faster?
> 
> Edit: forget the larger pulley. That would keep you at the same speed I think. But a smaller pulley on the alternator would speed it up. Am I correct?


Whether it is underpowered or not depends on the size of motor (hp), the speed the motor is running at (rpm), the "size" of the alternator (amps), and the ratio of gearing between the motor and alternator.
A 5hp motor should be overkill for any typical alternator if the motor is running at anything above idle. 
In fact a 3.5 hp motor should have no problem running a single alternator.

You were correct in you first post, a larger pulley on the motor will spin the alternator faster, as will a smaller one on the alternator.


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## 8thDayStranger

So help me out here. If I had, say a 3.5 hp motor and the alternator off a diesel truck, what would be the ballpark amount of power I could produce? Would this be big enough to power lights and fridge in a house? Electricity is not my strong suit so forgive my ignorance.


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## cowboyhermit

A very rough but useful conversion is 1hp=about 750watts
So that will tell you that you will get LESS than 2625watts of electricity. Probably a lot less depending on efficiency.

These units are best used to charge batteries, these batteries can then run things in the house through dc or run an inverter. A single alternator setup with a couple deep cycle batteries will have plenty of juice to run efficient light bulbs, a fridge can take more power than most realize (often the biggest consumer of electricity in a house).

It should be said though, small generators are pretty reasonable these days and for most people are an easier solution.


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## 8thDayStranger

Yeah. I was asking because I have a 3.5 hp motor and alternator and was curious if I could use it as a backup or as a portable unit. I have a 5000w generator but its heavy and I hate having to move it around when I need power in the yard. Might make an interesting experiment though.


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## Tirediron

An early 90s coleman 1750 watt generator had a 3.5 hp briggs engine on it, the engine would not hold rated rpm at an 1800 watt load. 3.5 hp x .75 should equal 2.625 kw, but the actual load capacity is only about 1.8 kw , this is a direct drive unit, so it should be more efficient.


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## cowboyhermit

Tirediron, that sounds about right, 1500 watts ([email protected]) would be a reasonable expectation. 1500 watts even with inefficiencies should be enough to run any fridge, or anything plugged into a normal outlet for that matter, especially if using a battery or two to balance out the surges.
Direct drive should be more efficient for sure but may not be the most desirable. If you have enough horsepower and noise is an issue you can gear up to allow the alternator to run at a decent rpm while running the motor slower. Of course using a DC system allows for quite a bit of wiggle room in rpm to begin with.


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## LincTex

cowboyhermit said:


> A 5hp motor should be overkill for any typical alternator if the motor is running at anything above idle. In fact a 3.5 hp motor should have no problem running a single alternator.


You might think so, but this guy proves you wrong, The first version stalled his gasoline engine under full load.
Here is the newer version, showing a 7HP engine to run a measly 60 amp alternator: 




Here is an RV'er writeup doing the same thing. He References a "alternators by Quick Start Q&A" that states 1 HP per 25 amps, and I think that is pretty darn accurate. http://www.rvforum.net/SMF_forum/index.php?topic=41000.0

This is a subject that has a lot of research to back it up in this forum:
http://www.microcogen.info/index.php?PHPSESSID=b5aqea8dau52691gm10hns3g47&board=12.0
ALL of your questions can be answered in there!!!

The Leece-Neville (Prestolite) alternators tend to be the most efficient.

Some cool ideas here:
http://alternatorparts.com/


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## labotomi

LincTex said:


> You might think so, but this guy proves you wrong, The first version stalled his gasoline engine under full load.
> Here is the newer version, showing a 7HP engine to run a measly 60 amp alternator:


Take the HP and multiply by 750 (to get watts), then divide the result by the voltage.

5hp * 750 = 3750W
3750W / 110V = 34.01 amps.

7hp *750 / 110 = 47.7 amps.

This is a direct conversion and doesn't take into account things such as the efficiency of the conversion. It would be best to oversize by at least 10%.

The 60 amp DC alternator in the video at 14.7V would be producing 882W which converts to 1.2Hp. I'm not sure why his 5hp motor wouldn't power this. It could be that the motor wasn't at the required speed to produce the rated power. Another possibility is that he was getting more than the 60amps out of the alternator. I only saw a voltmeter and it was reading over 16V at the battery terminals which means he had altered or maybe completely removed the normal regulator or disconnected the voltage sensing lead.


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## Roebears

Okay, for us less experienced folks how many batteries will a single alternator charge reasonably ????


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## LincTex

labotomi said:


> This is a direct conversion and doesn't take into account things such as the efficiency of the conversion. It would be best to oversize by at least 10%.


I think automotive alternators are only in the 40%-50% efficiency range. If that's true, then your numbers should be (at 50%):

5hp * 746 = 3730 (divided by 2 for 50%) = 1865 watts = 15 amps at 120 volts
7hp * 746 = 5222 (divided by 2 for 50%) = 2611 watts = 22 amps at 120 volts

That's probably more realistic.

http://www.microcogen.info/index.php#3


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## LincTex

Roebears said:


> Okay, for us less experienced folks how many batteries will a single alternator charge reasonably ????


This is like asking: "how long is a piece of rope?"

Please provide info on the size and number of batteries.


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## Roebears

LincTex said:


> This is like asking: "how long is a piece of rope?"
> 
> Please provide info on the size and number of batteries.


Let's say six deep cycle marine battery's, with a Delco 100 amp alternator.


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## 8thDayStranger

LincTex said:


> This is like asking: "how long is a piece of rope?"
> 
> Please provide info on the size and number of batteries.


I'm curious about this as well. Say it's a 5hp motor with 12v deep cycle batteries. What would be the max able to charge in the same time as a standard battery charger you'd find in anyone's garage?


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## LincTex

8thDayStranger said:


> What would be the max able to charge in the same time as a standard battery charger you'd find in anyone's garage?


Well, let's say your engine (5HP, 7HP, whatever) will spin an alternator at 100 amps (it had *BETTER* be something newer, like a Ford 3G 130 amp, or a Delco CS130 or 144.... older generation alternators WILL melt down!)

And your standard garage charger only puts out, say ten amps... then 100 amps will be 10 times faster, right? 
Well, maybe - up to a point - but you need to take into account the extra needed voltage and time to get to 100% charge, and I don't have time to type all of it out right now.

Be careful asking questions that are not easy to answer. There's more to charging batteries than what appears, and you need to do more research, really.

I am posting some REALLY good links in these posts, you need to go back and be reading them!!!
Read this (for the heat issues): http://www.madelectrical.com/electricaltech/delcoremy.shtml

CS130 and 144 wiring: http://www.hotrodlane.cc/newhtml/smallalt.html

Ford 3G wiring: http://www.bcbroncos.com/3ginstall.pdf


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## LincTex

What charge are they at, and what charge are you trying to get to? Getting to 100% takes a fair bit of time, I am afraid.

http://www.windsun.com/Batteries/Battery_FAQ.htm

http://batteryuniversity.com/learn/article/charging_the_lead_acid_battery

http://www.solar-facts.com/batteries/battery-charging.php

http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf

http://www.batterystuff.com/tutorial_battery.html

http://voltaicsystems.com/blog/choosing-a-lead-acid-battery-for-solar-charging/


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## labotomi

LincTex said:


> I think automotive alternators are only in the 40%-50% efficiency range. If that's true, then your numbers should be (at 50%):
> 
> 5hp * 746 = 3730 (divided by 2 for 50%) = 1865 watts = 15 amps at 120 volts
> 7hp * 746 = 5222 (divided by 2 for 50%) = 2611 watts = 22 amps at 120 volts
> 
> That's probably more realistic.
> 
> http://www.microcogen.info/index.php#3


How would you get 120V from an automotive alternator?

I meant for my examples to show the approximate size of the engines on the portable generators if people wanted to compare my results with what size motors come with the generators.

The last one is for the automotive generator, but you're right about them being inefficient. It would double the size of the motor required for the 60A alternator in the video, but it still only puts it around 3Hp


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## labotomi

Roebears said:


> Let's say six deep cycle marine battery's, with a Delco 100 amp alternator.





LincTex said:


> And your standard garage charger only puts out, say ten amps... then 100 amps will be 10 times faster, right?
> Well, maybe - up to a point - but you need to take into account the extra needed voltage and time to get to 100% charge, and I don't have time to type all of it out right now.


The faster the charge the less penetration you get into the plates. The outer layer is converted back into active material and forms an area which restricts charging deep into the plates. You'll get the battery charged quickly and when the charging stops the voltage will creep downward as the active material migrates inward.



LincTex said:


> Be careful asking questions that are not easy to answer. There's more to charging batteries than what appears, and you need to do more research, really.


I try to give basic general information so as not to describe a specific example and someone else use it for a different application.


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## cowboyhermit

LincTex, thanks for putting in the work with the info.
The gas motor in the video is running like [email protected] though doubt he is getting 5hp out of it

I have done several projects like this but I can't get the numbers right now because things tend to get cannibalized for parts around here

You certainly have to play with gearing and engine speed to find the sweet spot efficiency wise. I did have a 5hp hooked to a decent alternator and it never got close to stalling it but I got no numbers to back it up:dunno:


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## LincTex

cowboyhermit said:


> I did have a 5hp hooked to a decent alternator and it never got close to stalling it but I got no numbers to back it up


Hmm... I have a brand new electric start Robin-Subaru 7HP (same close-out sale as that guy in the video!) and a HUGE Leece-Neville that I could do some testing with. I also have a fresh 3HP Briggs I could use for "stall loading" purposes. That would only give max amps out, though.

The problem with this type of set-up is that these guys are asking how long it takes to get to 100% charge, and like Labotomi states - - - it takes a fair while. 
It's easier to get to say, 80-85% charge very quickly - but that last 15-20% charge takes *TIME*. No amount of Horsepower (or amps) can make time go faster.... but a few extra volts can sometimes help.

But you don't need a huge engine for a extra volts, you need a small fuel-efficient one that will run cheaply for a few hours getting the batteries "topped off".


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## smaj100

I'm not rocket scientist but I stayed at a Holiday inn once. 

Could you use the gearing mechanism from say a bicycle with the chain drive to help offload the motor to keep it at a steady rpm and the alternator? Thus with a bigger sprocket on the engine and small - medium on the alternator. Any thoughts? 

I've got an old riding mower sitting around just wasting away with a manual transmission on it, might have to pull a wheel lift it up in the air and test fire that puppy up, you should really be able to control the rpms with something like that.


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## 8thDayStranger

I was out and about the other day and passed an old grist mill not far from me and I started thinking. Would a water wheel hooked to an alternator and placed in a decent moving stream create enough energy to power an inverter enough to maybe charge a cell phone or power a light? It seems the lower speed would help protect the alternator from overheating but would these lower speeds cause too much power loss to be at all effective?


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## cowboyhermit

smaj100, that is a good idea, not sure how a bike system would hold up to that kind of use.
When I am MacGyvering something I usually use a variable pulley on at least one side, usually the motor. Just the plain, rotate for a different size type, this allows me to play around and get the pulley sizes right, of course you have to shut it off to make adjustments. A lot of farm equipment uses/used variable pulleys especially before everything was hydraulically driven and I have found those to be excellent for many projects, they allow you to adjust size on the go. I have often wished I could buy a pulley that is adjustable on the fly but never found one.

Using a variable speed system would certainly allow you to gear lower for a heavy charging load or switch to a high speed (high voltage) "topping off" and possibly even lower engine revs to save fuel.


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## cowboyhermit

8thDayStranger said:


> I was out and about the other day and passed an old grist mill not far from me and I started thinking. Would a water wheel hooked to an alternator and placed in a decent moving stream create enough energy to power an inverter enough to maybe charge a cell phone or power a light? It seems the lower speed would help protect the alternator from overheating but would these lower speeds cause too much power loss to be at all effective?


There is a lot of "Power" in a water wheel but not a lot of speed. You would have to gear it up a lot to get usable power from an alternator. Higher speeds mean fan on alternator spins faster as well.
There are alternators specifically for these kinds of projects that are "rewound" to produce usable power at much lower speeds.


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## LincTex

smaj100 said:


> gearing mechanism from say a bicycle with the chain drive... Any thoughts?


Yes - Bicycle chain and sprockets get destroyed quickly with the sharp power pulses from single cylinder engines with a "cogging" load like an alternator.

There is no need to reinvent this idea, and entire textbooks devoted to drives will prevent expensive mistakes with just a few hours of pleasant reading.



smaj100 said:


> I've got an old riding mower sitting around just wasting away with a manual transmission on it,


I use a converted Ford alternator mounted to my 18 HP lawn tractor as a portable DC welding rig. I used it everyday for several weeks when welding my fence piping, and still use it every couple of weeks.


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## LincTex

8thDayStranger said:


> It seems the lower speed would help protect the alternator from overheating


Incorrect.



cowboyhermit said:


> Higher speeds mean the fan on alternator spins faster as well...


Correct... Higher fan speed is far more important to cooling.


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## cowboyhermit

For anyone interested I have used these before, they are rewound and have permanent magnets installed to increase efficiency in a alternative type setup. They are also expensive :dunno:

http://www.windbluepower.com/category_s/1.htm


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## 8thDayStranger

Got it. Thanks!!


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## BillS

razorface1986 said:


> Hey everyone just theowing it out the but a push lawn mower engine , bondo and bicycle sprockets and a car alternator can be made in to a generator any other ideas out there want more info let me know


I think a home made generator like that would be way too noisy. Everybody in your neighborhood would know you were operating one. You'd have irate neighbors if you tried to operate it at night too.


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## LincTex

cowboyhermit said:


> They are also expensive :dunno: http://www.windbluepower.com/category_s/1.htm


Very overpriced, very limited efficiency, Limited output per dollar spent. I have not used one but have been told they are difficult to spin fast enough to cut-in properly.

http://www.fieldlines.com/index.php?topic=145421.0

http://www.fieldlines.com/index.php?topic=140552.0

http://www.fieldlines.com/index.php?topic=130196.0


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## cowboyhermit

BillS said:


> I think a home made generator like that would be way too noisy. Everybody in your neighborhood would know you were operating one. You'd have irate neighbors if you tried to operate it at night too.


Maybe Your neighbors would be irate but why be so negative toward others ideas without all the facts? Maybe you know the situation this person is in and the "You'd" is directed to him if that is the case I apologize. 
I know my neighbors could care less, sound doesn't carry that well through miles of hills and trees anyways. There is no reason this has to be any louder than any other gas generator. There are also many ways to reduce sound such as building an enclosure or sump and running at lower rpms.


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## smaj100

noise and heat could be overcome with a muffler or some form, a sound proofed box, with slots in it to help airflow, make some kinda fan blade to attach to either the alternator pulley or drive pulley to circulate air. Granted all of these things increase resistance and inefficiency.

But in a world gone to hell or some other htf, and you needed power to charge some batteries following an extended cloudy or wintery period where the solar, or turbine couldnt keep em charged I'd try something. Especially like someone else mentioned running it on woodgas...


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## LincTex

smaj100 said:


> a sound proofed box, make some kinda fan blade to attach to either the alternator pulley or drive pulley to circulate air. Granted all of these things increase resistance and inefficiency.... I'd try something. Especially like someone else mentioned running it on woodgas...


All of these criteria make a motorhome generator a perfect candidate. I know it isn't small (and it is NOT lightweight!) but my old Onan can't hardly be heard from 20 feet away. I know the neighbors can't hear it at all.

I would like to mount a big ol' DC alternator off the front someday. 
I think it would do well on woodgas (again, someday!)


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## cowboyhermit

LincTex said:


> Very overpriced, very limited efficiency, Limited output per dollar spent. I have not used one but have been told they are difficult to spin fast enough to cut-in properly.
> 
> http://www.fieldlines.com/index.php?topic=145421.0
> 
> http://www.fieldlines.com/index.php?topic=140552.0
> 
> http://www.fieldlines.com/index.php?topic=130196.0


I have heard the criticisms as well (others may not have though so it is good to bring it up) BUT in practice have had good luck with them as a simple, reliable, easily obtained unit. That forum (read it a lot in the past) has people saying they are not great however they are often misunderstanding things. For example some are saying the charts on windblue's website are wrong or deceiving when really they are just reading them incorrectly. Also you have people comparing one unit to another with completely different blades or even numbers of blades, that is just not a comparison. Basically what it comes down to in terms of criticism is mostly mismatched components and mismatched applications.
A unit like the dc-540 is intended to produce usable voltage at a low speed, it does not produce many amps at any speed (15amps at 2000rpm) and is not designed to. However spinning it at a low speed (500-750rpm) will produce around 10amps of power (120watts), that is it's purpose and I have seen it do that for a long time. They make units with much higher amps as well, including a one wire unit which can be very handy.

One example does not belong to me, it is on a horizontal axis turbine and has been functioning for many years and has provided many thousands of kWh over that time with no maintenance of the alternator.
I used one on a horizontal axis turbine (direct and geared) and it worked great. 
They are "zero cogging" as well 

I understand the criticism though imo most of it is misplaced and if there were more competing off the shelf solutions that would be great but under the circumstances I would not recommend against them since they have served us well personally.


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## LincTex

cowboyhermit said:


> In practice I have had good luck with them as a simple, reliable, easily obtained unit.


I am glad they did Ok for you. There is so much more to be gained without any additional cost, though. I think the biggest flaw is starting with a small case GM Delco 10SI. Sure, they are cheap and plentiful, but that does NOT mean it is a "good" design.

The "Large Case" Ford alternators or 27SI Delco units would be a FAR better platform to start with! Even better would be large Leece-Neville (converted). For only a small increase in size, you could have double the output.


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## cowboyhermit

I have made a generator myself, and played with the brake drum type but I have sooo many things on the go I have to draw the line somewhere. If there were similar established off the shelf competitors I would certainly be interested. I have tried lately to stop dealing so much in "shoulds" and just get some of this stuff going, if less than ideal.


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## LincTex

Roebears said:


> Okay, for us less experienced folks how many batteries will a single alternator charge reasonably ????


This BUD's for you!!!

http://www.microcogen.info/index.php?topic=2590.0


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## Laura

*Simple generator plans..*

Please send info to change my push lawn mower into a generator. I need simple terms. Is there a site with simple terms for me to try this??
Thank you for any direction or advice you can give.

Just a mom trying to learn what it take to be self reliant.


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## LincTex

Laura said:


> Please send info to change my push lawn mower into a generator. I need simple terms. Is there a site with simple terms for me to try this?


Laura, that may not be the best path for you to follow. You can use a lawnmower engine, but it might not suit your needs. At best, you can make some electric, but the efficiency isn't very high and you will pay a lot for the Watts you do make.

If you are living off grid, a lawnmower engine will supply only small amounts of power for a small amount of time. 
That is probably not what you want. 
I am just being honest. 

If you need a small powerplant that is portable and will make a little bit of power for a little while, then try this out: http://www.webpal.org/SAFE/aaarecov...y/electricity/lawnmower/generator/secpag.html

WARNING: that website will only get you *started* experimenting, and I feel is the answer to what you are asking. That set-up is not made to last but for just a few hours before things will crack and break apart. The same basic concept is also demonstrated here: http://theepicenter.com/tow082099.html

Again, it is a good start, but please don't have very high expectations. You will *NOT* be able to power your entire house with this, but you *can* run some power tools, kitchen appliances and lights/TV.

The second link has better information than the first one.


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## LincTex

One other thing.... if you have a GREAT junkyard to salvage your goodies from, you can find a pulley with a 7/8" bore to fit your lawnmower engine (most lawnmower engines are 7/8" shaft) from a semi-truck (or other large eqp, like a bulldozer) alternator.

If you have any semi-truck repair shops near, they *might* just give you an old one if you are a lady and ask politely  
In fact, you might get a volunteer to help with the project.

Almost ANY car alternator will do... the way they mount and the way the wires connect varies some, but when you are doing a custom install like this, none of that makes much difference.


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## don04348

A car alternator can be used to run brush type motors as found in skill sawsn vac, drills and a lot of shop equipment. When at your back woods camp that altenator can power lots of stuff.


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## LincTex

don04348 said:


> A car alternator can be used to run brush type motors as found in skill saws, vac, drills and a lot of shop equipment.


Yes, those are only voltage sensitive and don't care about frequency, or even if the power is AC or DC.

I wish there were an economical way to run the sealed induction motors in Refrigerator and Freezer compressors. Some say MSW inverters will run them fine, but I still feel funny about it. Still looking for a cheap PSW inverter...


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## LincTex

8thDayStranger said:


> This lawn mower gen is underpowered you say. Is this because of the alternator or the speed of the mower engine? If its the speed, couldn't you put a larger pulley on the mower and smaller on the alternator thus spinning the alternator faster?


You can play with pulley sizes to get the speed you want, but eventually you will just flat run out of horsepower, if the electrical amperage draw is too large.

Here is some more good discussion:
http://www.fieldlines.com/index.php?topic=143219.0

Quote: 
"Careful with the math and doing it on a piece of paper first usually helps.

If it is an alternator that will produce *90 Amps*, then if the voltage is regulated to 12V it will be putting out 1080 Watts. (NOTE from Linc: Most alts run the voltage around 13.8 or a little higher)

At the same time, however, it is generating a huge amount of heat in the wire. I don't happen to know the coil resistance of an auto alternator, but for the sake of argument, it might be about 0.5 ohm. In that case the resistance losses alone will be I-squared-times-R = (90)*(90)*(0.5) = 4050 Watts

Also of concern is the voltage drop across the rectifier, which is probably 1 Volt, therefore I*V = 90*1 = 90 Watts.

The input power required for any machine must equal ALL of the outputs.

The total power required to DRIVE the alternator is 1080+4050+90 = 5220 Watts. That is almost exactly equal to 7 HP.

That motor is undersized. (Though anybody who can correct my assumption about the winding resistance could show they are better matched than this)."

Dag-nabbit, I still need to get one built and play with it and get some real numbers!!!!


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## 8thDayStranger

Thanks! This thread is really interesting me. My problem is it gets really techy and I get lost. Not anyone's fault but mine. The questions I asked were to get an idea of what an alternator and a small engine could produce. Maybe if I really focus I can figure it out. I just get lost in all the numbers. 

Another question. Earlier it was mentioned that the alt overheats or has the potential to burn up. Is this from physical heat or overworking the internal parts? If its physical heat, then would an external cooling system IN THEORY help get a little more life out of an alternator?


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## LincTex

8thDayStranger said:


> Is this from physical heat or overworking the internal parts?


The first happens because of the second.
The math isn't hard... just work through it until you get stuck and then ask, we will help.

Besides, I will bend over backwards to help someone if they make the effort to even try. 
I *HATE* helping people who make no effort on their own. Show me you are trying, and I'll give you the shirt off my back. 

If you do something like this, you will probably want a way to adjust the field rotor current (easy to do). Applying large load all at once (like a bank of batteries) is bound to cause it to stall out (come to a complete stop).

Get it all spinning, and slowly bring the field juice up to where the engine can handle the load.

Do you have a spare alternator to play with? What is it?


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## LincTex

For anyone who is MEGA (and I do mean *MEGA*) serious about using an alternator, there is a 15 page .pdf written by Bob B. Gayle where he tells how to get up to 80% efficiency (yes, amazing - and you won't make that with a 70's Chevy 10SI alternator)

http://www.microcogen.info/index.php?topic=157.0

Or - - - PM me and I can send the .pdf

The best a typical alternator will do is about 50%. The attraction is they are cheap and available. The new ones are amazing... the Mitsub built 200 Amp Police Crown Vic alt I have has incredible output for such a small size.... However, my back-up plan is a Leece-Neville truck alternator.


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## 8thDayStranger

I have an old delco off a diesel truck somewhere in the warehouse here at work. Don't know exactly where it is and a 4 hp Kohler I think it is off an old water pump that the pump housing froze and busted on. I'll see if I can find that alt.


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## LincTex

8thDayStranger said:


> I have an old delco off a diesel truck


I don't think 4 HP will do it... but a big unit like a 27SI Delco is a darn good starting point! I guess you could use the 4 HP engine.

Are you sure? Did Kohler make a 4 HP engine? The smallest I have seen is 7HP from a Cub Cadet... and it put out closer to 10HP. Those old K series Kohlers are STOUT engines!

Let's see some pics!


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## 8thDayStranger

I was wrong. It's a Honda GX120 4hp. Still looking for alt. somebody may have grabbed it for something.


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## labotomi

8thDayStranger said:


> Another question. Earlier it was mentioned that the alt overheats or has the potential to burn up. Is this from physical heat or overworking the internal parts? If its physical heat, then would an external cooling system IN THEORY help get a little more life out of an alternator?


Virtually all of the heat from an alternator comes from electrical current.

Don't worry about the units but you can use;
current squared divided by resistance I^2/R

you can use this to get an idea of what will happen if you add extra loading to the alternator. Resistance and current changes to the circuit have the opposite effect (raising current increases heat, raising resistance lowers heat), but since the current portion is squared, it's effects are more pronounced Plus you're concerned about the alternator and not the entire circuit

eg. if you have a battery bank that you charge regularly and decide to add an identical on in parallel to double your capacity, the resistance will be halved but that change is in the batteries and not the alternator. The alternator current doubles. Since the heat due to current is squared, doubling the current quadruples the heat generation.

As for an external cooling source helping extend the life of the alternator... it would help if you had a way of moving "cold" air across the alternator. Simply blowing more air of the same temperature may help a little, but you need a larger difference in temperature to increase the heat transfer via conduction.

Putting a large fan on it would help a little. Putting it in a box cooled by something like a vortex cooling unit would help a lot.


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## LincTex

labotomi said:


> Putting a large fan on it would help a little.


I think all modern alternators, and most older 3rd and 4th generation have a pretty decent fan already. Keeping it cool enough really just means making sure it is spinning fast and not overloaded.

Old 1st and 2nd generation Ford and GM alternators do just fine with 35-40 amps, but that is all they can really handle with the fan they are given. I know "quick start" and others make 80-100 amp upgrade kits for these, but those are just for "fast and short" bursts of power, like when using a winch. Charging a battery bank for hours it too much.

Just for a ref, the "large case" alternators, like the big Leece-Neville truck alternators, can only handle 8000 shaft RPM - - MAX. Thanks to Bob G (Robert Gayle) for passing that info on to me. As an aside, the claw-pole rotor inside the 200 amp Mistsu alternator (Crown Vic police) I have looks to be STOUT. I'll bet it was tested at max engine RPM for days! It also has double cooling fans.


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## labotomi

LincTex said:


> I think all modern alternators, and most older 3rd and 4th generation have a pretty decent fan already. Keeping it cool enough really just means making sure it is spinning fast and not overloaded.


I agree completely. I might have been mistaken, but I though the subject of increasing output was brought up. I was addressing that possibility which may or may not have been relevant.

Even with running an alternator at voltage and current outputs that don't exceed the ratings, alternators have a duty cycle. They're not designed to put out maximum output constantly. Someone else may know that figure, but if you're familiar with thermal damage curves with respect to motors, it's the same. I wouldn't want to run a 120A alternator at 120 amps for longer than a few minutes.

The design limitations of generators are current capacity, the voltage it can generate and the amount of heat removal. Current can be addressed by increasing the conductor size. Voltage can be addressed by improving the insulation on the conductors/windings. The heat removal can be addressed but the available methods available to an automobile alternator are 
1. Increase the surface area for heat removal. This would increase the size of the alternator and contradicts the efforts to keep it compact.
2. Some sort of external cooling system. Not worth the extra expense in a car.

In just about every generator construction, the actual design usually comes down to a decision of the tradeoff between higher ratings or smaller units.

For a home application an alternator could be modified to put out quite a bit more than it's designed to do. The windings are capable of higher currents than the rating and the voltage output wouldn't change. The limiting issue would be the heat generated.

Especially in the case of older alternators, the field circuit can be modified to reduce the voltage "droop" due to higher loads. I'm sure it can be done in newer alternators as well, but probably with more difficulty.

I haven't done it personally but I do know of some people that like to "tinker" with things... running them as hard as they can until they fail and they did this with a couple of alternators and I remember them saying that they were able to get about twice the output for a while until the windings cooked. The only thing they did was alter the regulator. I don't think they added any extra cooling. If they had added more cooling they may have been able to run them without damage due to the heat, but this is only my opinion.

I'm certainly no expert with alternators, but they are basically the same as any generator and those are something with which I have a lot more experience.

Any alternator has a feedback circuit to control voltage output. Adding a rheostat in series with that portion of the circuit would allow someone to cause an increase in the output voltage to compensate for the drop at high current levels. The downside is that voltage will rise above the designed limit if the load current goes down to normal levels. This is just the easiest way. I'm sure with time it could be automated to adjust based on output voltage alone.

Even one of the old solenoid/mechanical regulators that pulled rods that caused contact buttons to close or open which increased or decreased resistance simply due to the current output would work. I wish I could remember the manufacturer of the regulator that used this. There's probably more than one, but I remember specifically one that was used on the older US Destroyers (all of which are now decommissioned). The name Woodward comes to mind, but that could have been what we used on subs which was not electro/mechanical. Plus Woodward isn't exactly a specific term. That company produces so many types of regulators that it would impossible to pin down.

Sorry, this ended up being way more than I intended to post. You know enough to realize that I'm not contradicting what you say. It's just an option that could be used "if" the situation were dire. I'd much rather run equipment within it's limits than push them.


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## LincTex

labotomi said:


> Even with running an alternator at voltage and current outputs that don't exceed the ratings, alternators have a duty cycle. . I wouldn't want to run a 120A alternator at 120 amps for longer than a few minutes.


I know the Ford 3G 130 amp is around 90% duty cycle... I know for a fact it will put out over 165 amps cold. I think the rating result came about from police car use (Crown Vics) requiring more accurate ratings so they know what equipment can be installed before running into overdraw problems. I need to go back and look, but I am pretty sure FoMoCo guaranteed at least 115 amps @ 100% to satisfy specs. I can't imagine a cop car using more than that, IMHO.


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## labotomi

LincTex said:


> I know the Ford 3G 130 amp is around 90% duty cycle... I know for a fact it will put out over 165 amps cold. I think the rating result came about from police car use (Crown Vics) requiring more accurate ratings so they know what equipment can be installed before running into overdraw problems. I need to go back and look, but I am pretty sure FoMoCo guaranteed at least 115 amps @ 100% to satisfy specs. I can't imagine a cop car using more than that, IMHO.


90% duty cycle is higher than I would have expected for a general alternator but I can understand if it's spec'd out for police car use.


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## LincTex

I will stick with the Ford 3G series for now, because they are so well respected. You can see that the actual output is a fair bit higher than the rating, but I don't know if this is cold or hot. For the time being, I will accept the data from this website as truthful:
http://oldfuelinjection.com/?p=75

QUOTE: "Fords 3G alternator was a giant leap in technology and quality. The 3G was internally regulated, used two internal cooling fans, sealed bearings, and had a superior battery stud. The 3G's were more efficient, and produced more amperage at idle than any of its predecessors."










All alternators can run at "100% duty cycle", it's just a question of what percentage of its "max rated" output can be sustained at 100% indefinitely.

I have a hunch that semi-truck alternators can operate at rated amperage 100% of the time.


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## labotomi

LincTex said:


> I will stick with the Ford 3G series for now, because they are so well respected. You can see that the actual output is a fair bit higher than the rating, but I don't know if this is cold or hot. For the time being, I will accept the data from this website as truthful:
> http://oldfuelinjection.com/?p=75
> 
> QUOTE: "Fords 3G alternator was a giant leap in technology and quality. The 3G was internally regulated, used two internal cooling fans, sealed bearings, and had a superior battery stud. The 3G's were more efficient, and produced more amperage at idle than any of its predecessors."
> 
> All alternators can run at "100% duty cycle", it's just a question of what percentage of its "max rated" output can be sustained at 100% indefinitely.
> 
> I have a hunch that semi-truck alternators can operate at rated amperage 100% of the time.


I wasn't disputing your statements at all. Sorry if I gave that impression.

If one is rated at 100% duty cycle, it shouldn't be harmful to modify them to output more than their rating for shorter periods.


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## LincTex

labotomi said:


> I wasn't disputing your statements at all. Sorry if I gave that impression.


No, you didn't! That was just out there for "general info".



labotomi said:


> If one is rated at 100% duty cycle, it shouldn't be harmful to modify them to output more than their rating for shorter periods.


Oh, yes. K-type thermocouples have come down in price considerably! It would be a piece of cake to epoxy the thermistor bulb into the stator windings to get some really accurate temp data.


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## labotomi

LincTex said:


> Oh, yes. K-type thermocouples have come down in price considerably! It would be a piece of cake to epoxy the thermistor bulb into the stator windings to get some really accurate temp data.


I think you meant thermocouple ("k" type") though a thermistor would work. I'm just not very familiar with them since they're not used here.

Honestly I don't keep track of the prices even though I'm ordering these all the time. We go through dozens of K type and several S types per week. Most other places we use RTDs. I have a good supplier and just specify the type and configuration. The large range of a K type might be ok if the price is right and a high resolution probably isn't needed anyway. Definitely would be cheaper than S type


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## LincTex

labotomi said:


> I think you meant thermocouple ("k" type") though a thermistor would work. I'm just not very familiar with them since they're not used here.
> 
> The large range of a K type might be ok if the price is right and a high resolution probably isn't needed anyway.


Yeah, I only had three hours sleep, I doofed that. 0-300*C that has the std VOM connector are only about 5 bucks now


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## labotomi

LincTex said:


> Yeah, I only had three hours sleep, I doofed that. 0-300*C that has the std VOM connector are only about 5 bucks now


Are you sure you're getting a K? The range should be a lot larger.


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## LincTex

labotomi said:


> Are you sure you're getting a K? The range should be a lot larger.


Good question. I guess you get what you pay for. Worth looking into at those prices, though.
Here:
http://www.ebay.com/itm/2M-K-Type-T...hermometer-for-multimeter-meter-/330897562161

http://www.ebay.com/itm/New-K-Type-...ometer-Probe-Sens-1-Meter-Cable-/160938948033


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## labotomi

LincTex said:


> Good question. I guess you get what you pay for. Worth looking into at those prices, though.
> Here:
> http://www.ebay.com/itm/2M-K-Type-T...hermometer-for-multimeter-meter-/330897562161
> 
> http://www.ebay.com/itm/New-K-Type-...ometer-Probe-Sens-1-Meter-Cable-/160938948033


We're using K types at 2100F so that's much higher than 300C

Type K should have a range of -200 to 1250°C and that's a constant. If it's made of Nickel-Chromium and Nickel-Aluminum that would be it's range. There's no way to change this. I wonder if the ones on Ebay are specifying the limits of the cable insulation or connector.

If they're using extension grade wiring... that's not it's purpose. It's not accurate for measuring. It's purpose is to provide wiring from the thermocouple to a remote measuring device for cost reduction.

http://www.omega.com/techref/thermcolorcodes.html

http://en.wikipedia.org/wiki/Thermocouple#K


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## helicopter5472

OK any info on converting a small gas engine into a steam engine to run a generator


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## cowboyhermit

helicopter5472 said:


> OK any info on converting a small gas engine into a steam engine to run a generator


That might warrant it's own thread, not too difficult but a lot more involved than hooking a gas motor to an alternator. Good to see people trying this stuff, I have only played with steam a tiny bit, I had some serious plans but they got bumped way down my list 
I don't know if anyone on here has much experience with what you are asking, hopefully we will see.


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## Startingout-Blair

helicopter5472 said:


> OK any info on converting a small gas engine into a steam engine to run a generator


I would be interested in this topic also!


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## Shammua

Makes me wish I hadn't gotten rid of my old lawn mower..... Wait I still have my pressure washer, the water fittings all broke but the engine runs fine. Ill have to see what we can come up with for that. Hmmm!!!!


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## LincTex

helicopter5472 said:


> OK any info on converting a small gas engine into a steam engine to run a generator


It's a LOT of work. This is something that's fun to toss onto the table in the "man cave" and show your buddies when they are over for a beer, and that's it. It will spin but can't do any real work.

You need a cast iron bore and piston. That can be found in very old small engines, but nothing you find today. You would have better luck starting with an older air compressor pump.

You need a pretty long stroke, relative to the bore size. Most small engines are at about their limit with the amount of stroke you can add. Big bore/short stroke engines use a lot more steam to make the same power output.

Where are you going to buy "Steam cylinder oil" at?

"Poppet valves" only work on the exhaust side, the intake side will always be pushed open by steam pressure no matter what. You need a valve the is positive operating, no springs involved.

What do you know about boiler operation???? The "learning curve" with boiler opns is often *fatal*. Sure, you can play it safe with low psi, but then you have a big engine with low power output. So the more power you want (and you will want it), the more pressure you are going to play with, and it keeps climbing until you make a bad mistake (EVEN IF your boiler is rated for that pressure!). The knowledge needed to "do steam" properly is about the same as a bachelor's degree!

It also takes a LOT of fuel to make a good steam engine work. Be prepared to chop and haul a lot of wood. 
A LOT. 
The efficiency numbers are really not that good at all.

I searched for Dan Bartman and his setup: ( "otherpower steam" )

http://otherpower.com/steamengine.html


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## LincTex

Startingout-Blair said:


> I would be interested in this topic also!


You can learn a LOT here:
http://www.smokstak.com/forum/showthread.php?p=888476


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## Shammua

So I just took apart my broken pressure washer and besides the broken pressure part everything looks good.

For those experts out there tell me if this sounds like a decent plan to make it into a generator.

First step is to put a pulley setup on the bottom so it can run a belt. From the belt it then runs to an alternator, the alternator is then tied to a bank of batteries. Now this setup in turn is tied to an electrical panel that I can plug into.

I know there will have to be some sort of voltage regulator or other stuff like that... Details what what should be done or parts I should use are welcome. I feel that this would be a hijack of this thread so I will start a new one.


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## LincTex

Shammua said:


> First step is to put a pulley setup on the bottom so it can run a belt.


Straight engine shaft, or tapered? What is the diameter and length? What model/HP engine?



Shammua said:


> I feel that this would be a hijack of this thread so I will start a new one.


Post a link when you do. Got lots of great info for you


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