ac generator from car alternator

[Jim Krapf]

Can anyone lead me to a site where I might find plans for building a 120 volt generator using a car alternator. I know that it can be done with out using an inverter.
I would like to use two together to make 220 volts.

 

[IH2444]

it can be done but you would only have 1/3 of the current available as alternators are 3 phase AC until rectified into DC.

Also the frequency would have to be controlled with the rotational speed of the alternator.

I would also think that maintaining the phase relationship of the 2 alternators would be very problematic at best to get 220 volts. The laternators have to be 180 deg out of phase with each other for the 220 to work and that relationship must be maintained and cannot vary or you will let the smoke out of the alternators and whatver you are running with it.


I am not sure how the insulation on the windings would hold up at 220 volts either.

Now that I think about it I would not recommend trying it. I have heard of making 120v ac generators out of them. I think you would be better off buying a brushless geneator head.

there are also plans out there to make welders out of them.

 

[IH2444]

it can be done but you would only have 1/3 of the current available as alternators are 3 phase AC until rectified into DC.

Also the frequency would have to be controlled with the rotational speed of the alternator.

I would also think that maintaining the phase relationship of the 2 alternators would be very problematic at best to get 220 volts. The laternators have to be 180 deg out of phase with each other for the 220 to work and that relationship must be maintained and cannot vary or you will let the smoke out of the alternators and whatver you are running with it.


I am not sure how the insulation on the windings would hold up at 220 volts either.

Now that I think about it I would not recommend trying it. I have heard of making 120v ac generators out of them. I think you would be better off buying a brushless geneator head.

there are also plans out there to make welders out of them.

 

[Oldmax]

You can get about 120 volts out of a car alternator "BUT THE HERTZ WILL BE ABOUT 100 . To do this you have to feed a full 12 volts to the field winding. It is not practical you can buy a 120/240
volt power unit cheaper than you can build one .

 

[Anonymous-0]

Fundamentally what you need is to bring out the AC wires from where the stator winding connects to the diodes. Three of them. Then run them through a 3 phase step up transformer, but it will be three phase if you want to use the power capability of the alternator. It won't be 60 Hz, it will be a higher frequency. And depending on the transformer, it might be 120 or 240 or both. The voltage regulator can run on the original DC output, or you can build a new regulator to work from the rectified line voltage output.

A Leece-Neville truck alternator may already have the AC leads brought out. One that I have does.

Decades ago, there used to be an alternative regulator that would make the alternator put out 120 volts DC for use with lights and Skil saws (series motors run better on DC than on AC) and drills (but not variable speed drills). It probably blew the diodes from excess voltage on occasion and I've not seen it advertised in a long time.

What you want is a silk purse from a hog's ear and that's not easy, nor does it always give you the result you thought you wanted.

Gerald J.

 

[MarkB_MI]

You can bypass the regulator on most alternators and get about 90 volts DC. That's adequate to run power tools with brush-type motors such as drill motors. (Brush-type motors don't care if you feed them AC or DC.) Folks used to do this when small generators weren't readily available. With the current prices of small portable generators, I can't imagine anyone doing this.

There's no way you're going to be able to use the AC output of an automotive alternator. It is three phase, plus the frequency is going to be too high. As far as adding up two alternators to get 240 volt single-phase power, that was discussed a couple of weeks ago. The alternators need to be locked into phase together, which wouldn't really be practical, even if the alternators were single phase, which they aren't. You could conceivably couple two unregulated alternators in series to get about 180 volts DC, but this would mean isolating the chassis of one from ground, and then you have a potentially hazardous condition of one alternator case being at 90 volts referenced to ground.

 

[Bob]

"BUT THE HERTZ WILL BE ABOUT 100"

You are OFF, EXPONENTIALLY with that figure. (At least at alternator speeds that will generate a usable voltage.)

 

[buickanddeere]

The old half baked harebrained idea of 120V from an alternator still lingers like a bad smell. Mostly due to reprints or reprints of the 1960's, 1970's plans now applied with good intentions to wind and water generators.
Cheap, readily available problem is at beast they are only good for charging 48V battery banks to supply an inventor.
Real 120/240v 50/60Hz two bearing generators are dirt cheap on ebay or from "back to earth" vendors.

 

[guido]

Jim Krapf.
It is inpractical to make a/c power out of an
alternator. 90 to 100 volts a/c at best.
240? How about frequeny?
Guido.