Will a commercial genset work?

[RobT]

I've just had a peek in the local hardware and they are selling a 750watt genset for au$100! My first thought was,"A cheap gennie for my 'mill-in-the-making'".

It is rated at 750w AC and also has a 14.4v DC output. (not sure of the rating)

Am I heading in the right direction, or is it too much to modify such a beast?

In Aus, I'm looking at mega-dollars for any decent neo's, so alternatives are alwayw attractive.  Any input is much appreciated!

Rob T.

[commanda]

I'm in Aus, which hardware store? One of the major chains?

From what little I've seen (ebay mostly) the watts seems to be shaft power, and not really related to electrical output. Probably about 300 watts electrical, and not terribly efficient, if you were thinking of seperating the alternator from the internal combustion engine & putting blades on it.

If you want a good cheap alternator, look at the Fisher & Paykel smart drives. (There was a whole washing machine in last weeks Sydney Trading Post, broken pump, $50.00). I've got most of one, and will post some piccies & info next week. Also, with these motors, I think it's a mistake to re-wire them for lower voltage. Encourages line losses in moving the power from the top of the tower to the batteries. Better to run the line high voltage, with toroidal transformers at the battery end. I picked up 3 x 250 VA toroidals from Oatley electronics. They should be better than 90% efficient. Like I said, photos & more info next week after I run it up.

Amanda

[RobT]

Hi Amanda!  Thrifty-Link stores in SE Queensland are running the sale until Sept 5th.

It's a 'Thiesel' 750w with 2hp engine.I'll look forward to your pics and info with the Fisher & Paykel Motor. I'll keep an eye out in the local rag for a cheapie!

Thanks! Rob T

[dconn]

Hi Rob,

I had a small petrol generator (Honda) - Unfortunately I lost it (stolen I think - when I needed it again I couldn't remember where I'd stored and I've never seen it since) - anyway it was AC output but also had DC too.  The problem was the the DC output was rated very low (single figure amps @ 12V) even though the AC was more like a KW.  I think that the generator used an induction generator to produce the AC (again I cant be sure now because I dont have it anymore).  This was not much use to me because I generate and store all the power at 12V into batteries and I didn't want to use lots of petrol just to get a few amps at 12V out.  

Derek

[RobT]

Hmmmm, methinks I might just buy one and use it as a little backup machine or something rather than utilize it for a mill.  I've just received Hugh Piggott's book on building, but I'm still a little doubtful about my skills. I'm learning a lot just listening in to this board! Thanks for the input!

Rob T.

[wpowokal]

Rob if I read your post correctly you are thinking of utilising this units generator on a wind turbine.

If this is so then it will most probally be a 3000 RPM unit which is not achieveble except by gearing and then if not run at close to that speed

 electrical problems can develope.

Oatley have scooter motors currently available but they too are very high speed and not suitable,http://www.oatleyelectronics.com/

Tape drive motors (TDM's) are simple just add blades or as stated by others Fisher and Pykle motors are a greate resorce.

Try http://66.140.203.100/gallery/albums.php

scroll down to Bruce the ausie bushman he has F&P info, close to you also.

Also on the board search for TDM's and check out diarie entries for TomW he has posted TDM  data.

hope this helps

regards Allan

[wpowokal]

Link to TomW's diary entries, sorry for being lazy, has F7P and TDM's

http://www.fieldlines.com/user/TomW/diary

Allan in WA

[systemtwo]

where about in W.A are you allen I live in perth, west swan

[DanB]

Just chiming in to agree with others here.

The 14 volt output would be @ very low current I suspect, probalby not terribly useful.  And, for any output - it's probably running up around 3600 rpm.  It most likely has a wound field which will make it inefficient at low output levels (most wind turbines spend most of their time at low output levels 'cause most winds are low!).

Not a very good choice In my opinion... you'd be much better off with a car alternator, and that too.. would be a poor choice for similar reasons.  You need something that produces at low rpm.  Even a very small wind turbine (say 4' diameter) should have a generator that hits cutin voltage at fairly low speed.... like 300 or 400 rpm max.

[BruceDownunder]

Hi Rob. I saw a little green gen set for 170 bucks at mitre 10 .  The guy said it would just poer your frig ,maybe . but a couple of lights would be ok.

had a two stroke noisy whipper snipper engine.

But ,at 100bucks , I'll try to get one and stash it away ,just in case.

Thanks

Bruce

[Ungrounded Lightning Rod]

I had a small petrol generator (Honda) - Unfortunately I lost it (stolen I think - when I needed it again I couldn't remember where I'd stored and I've never seen it since) - anyway it was AC output but also had DC too.

That wouldn't be the little blue ultra-quiet squarish suitcase-style one, would it?  Number something like 1000 but produces 650 watts?  I've got one of those.  Sweet unit.

The problem was the the DC output was rated very low (single figure amps @ 12V) even though the AC was more like a KW.

They got the 12v by tapping the power windings near the neutral end and hanging on a bridge rectifier on it.  They apparently didn't use heavier wire for that part of the winding so the current available at 12v is about the same as the current available at 120v.

Don't hook up both the 12v and the 120v at the same time, as by charging your trailer batteries at the same time as you're powering the 120v trailer appliances.  Neither of the battery connections is at the neutral voltage - instead they postive and negative output posts alternately take a half-cycle up from the neutral level.  If your battery has one side connected to your 120v neutral you'll be shorting the generator's 12v winding from hot to neutral through some of the rectifier diodes.

I think that the generator used an induction generator to produce the AC (again I cant be sure now because I dont have it anymore).

The one I had did that.  Two-phase stator (one was excitation tuned with a capacitor, the other the output.)  Wound rotor with diode for fixed location magnetic poles (rather than the slowly sliding ones you get with a squirrelcage).

[BT Humble]

If you're looking for "cheap", then a motorcycle stator and flywheel might be a good start.  They look rather like a Fisher & Paykel rotor/stator set, but built a bit more sturdily.

Alternatively, $100 worth of magnets isn't really that much when you consider the number of hours of work you're putting into a machine.

Hey, these guys (in Australia) are having a stock clearance sale!

http://imsolutions.cytek.com.au/index.php?page=catalogue&catid=33

BTH

[wpowokal]

150K south of you, Wokalup (three mile short of Harvey)

[dconn]

Hi Ungrounded Lightning Rod,

"That wouldn't be the little blue ultra-quiet squarish suitcase-style one, would it?  Number something like 1000 but produces 650 watts?  I've got one of those.  Sweet unit."

It was blue all right and I think it might have said 1000 (and 650 is about as much as I ever got/needed from it) - and quite small (retangular/box shape I'd say) - not to heavy or noisy.  Its a pity its gone now.  Very interesting to hear how they get the low voltage [dc] out too (the other smaller set of windings).

The generator I had was 220V (I'm in Ireland) - I dont know if there was much difference between US/European versions (the power output was modified into a UK/Irish power socket by my father-in-law - it was probably european before that).

Derek

[Ungrounded Lightning Rod]

Sounds like the same puppy.  Green light and voltmeter?  Two

little clear reset buttons on the circuit breakers for the

line voltage and charging circuits?  Recessed pull-cord start

down at one corner?  Off-run-chokestart control lever?

Round black fill cap and small round gas level meter on top?

I've got an experiment I'm going to try with mine, some weekend in

the next month or so, I hope.

So far I've only used it for blackout power at my house.  (It can

handle the refrigerator startup plus a couple lamps.)

I'd have liked to use it to power the cloeman air conditioner on my

camping trailer, but it won't work as is.  (I understand coleman makes

a smaller AC unit that it WILL drive, by the way.)  It has about enough

rated power to run the AC.  But when the compressor tries to start the

inrush steals the excitation and causes it to quit putting out.

I understand that this is typical of induction generators - they

can only start a motor of a much smaller size than what they could

push into a resistive load, due to the inrush suck-out effect.

But I recently acquired a branch shredder with a dual-capacitor

1.5 horse motor (and a BIG flywheel).  The dual-cap motor doesn't

suck out the excitation (though it pulls enough current to blow

the breaker before it gets spun up).

So I'm going to make an adapter box:  Power in, through a large

incandescant bulb with a bypass switch, to a pair of outlets, one

for the shredder, the other for the trailer.

Idea is to plug the input hoppers on the shredder (so it won't

waste power pumping air) and start it up with power through the

lightbulb as a balast resistor until it's up to speed.  Then

while it's spinning (and the lightbulb is bypassed), hook up the

trailer AC in parallel with the motor.  Ideally motor/flywheel

combination will act as a generator to provide the inrush for

compressor start.

If that works I'll get another motor, make a flywheel and protective

enclosure for it, and use it as a standalone "peaker" in place of

the shredder. This should let me run the trailer AC off the tiny,

quiet genny for hot days at the no-hookup campground. B-)

If I use something like a clothes dryer motor (which also has a

high-current normally-OPEN switch, used for safety to only allow

the heating element operate when the motor is up to speed), I

should be able to automate the bypassing of the startup balast

resistance, too.  Then I'd have a black-box I could just plug

into the genny to let it run high-inrush loads.

I'll post an article if it works.  (Or maybe even if it doesn't.)