Author Topic: Rewinding car alternator  (Read 2143 times)

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mohamedtoure45

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Rewinding car alternator
« on: April 06, 2017, 05:53:17 AM »
Hi guy, Please someone can tell me how to modify car alternator to wind alternator, and how to rewind the stator as well as the size of the wire, number of turn.
I am new to try for that project because where I am living they are no electricity.

Thanks

Bruce S

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Re: Rewinding car alternator
« Reply #1 on: April 06, 2017, 06:43:06 AM »
I've split your topic into a new one.
This will make it easier for people who respond.
The previous topic is quite old.

Cheers
Bruce S
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Warpspeed

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Re: Rewinding car alternator
« Reply #2 on: April 06, 2017, 08:34:08 AM »
A much easier way than rewinding the alternator would be to feed each of the three existing windings into three external transformers, and wind those to suit the voltage and current you require.

hiker

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Re: Rewinding car alternator
« Reply #3 on: April 06, 2017, 04:59:28 PM »
if you can find a truck alt...their bigger...can hold more wire...easy enough to rewire if you know the tricks....you can wave wind..or go with seprate coils..like a 9 and 12 setup..i belive you can fit two sets  of nine coils in their..ile have to look thru my files..  treadmill motors make great light dudy gens as well...find a used high voltage on...like a 220 ---a 110 motor takes more rpm to hit around 12v output...
WILD in ALASKA

hiker

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Re: Rewinding car alternator
« Reply #4 on: April 06, 2017, 05:04:43 PM »
with one set of coils installed...
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hiker

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Re: Rewinding car alternator
« Reply #5 on: April 06, 2017, 05:09:29 PM »
you can even stack stators ..one atop the other for a bigger alt.....built a few of those...bike gens...wind gens..................fun stuff. 
WILD in ALASKA

Adriaan Kragten

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Re: Rewinding car alternator
« Reply #6 on: April 07, 2017, 12:38:21 AM »
In chapter 1 and 2 of my free report KD 341 I give my experiences with car alternators (see www.kdwindturbines.nl). They have many disadvantages. One is that you need a rather high electrical power of about 28 W to build up the magnetic field in the armature. As the generator has a rather low efficiency of only about 50 %, the rotor has to generate about 56 W only for building up the magnetic field. I have made a new armature with permanent magnets to eliminate this problem. But with this armature you need a rotational speed of about 900 rpm to reach a DC voltage of 12 V.  You can halve this voltage by making a new stator winding with a thinner wire and with the double number of turns per coil but as this winding will have a higher resistance, the generator efficiency will drop because of I^2 R losses. But for a PM-armature you don't have the losses for building up of the magnetic field, so the efficiency at low powers might still be acceptable. But only modification of the stator winding and not using a PM-armature is a bad idea because then you have the magnetic losses and the I^2 R losses together and then the efficiency will be very low.

hiker

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Re: Rewinding car alternator
« Reply #7 on: April 07, 2017, 06:39:20 PM »
i ran a stock car alt off of one of my pedgens..to get the ball rolling all it took was a hit from a 9volt transitor radio batt. at the field termnal....the field coil is like a 50watt load by itself....so to make things easyer[to pedal]..i ran the field coil in series with a 12v taillight bulb...that lowered the load from the field coil..sence you dont want full output from the alt..as in amps..watts.....from their i ran three 12v headlites off of it...  it was just a try out....
WILD in ALASKA

hiker

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Re: Rewinding car alternator
« Reply #8 on: April 10, 2017, 10:55:25 PM »
HERES A BIG DC TREADMILL MOTOR..HOOKED UP TO ONE OF MY PEDGENS...https://www.youtube.com/watch?v=AwX0nmOh__U
WILD in ALASKA

kevbo

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Re: Rewinding car alternator
« Reply #9 on: April 20, 2017, 12:51:56 PM »
I will add my voice to those saying that an automotive alternator is a poor choice.   I have rewound a couple of them for automotive applications where a replacement was not available.  They are made to be inexpensive to produce, and just adequate in service.   I have also rewound a few motors, and the higher quality was apparent. 

Alternators seem attractive because you can regulate in automotive fashion by controlling the field current, but this is a power loss, and the prime mover (windmill?) can run-away if the regulator or field winding, or brushes fail.   The claw-pole design that is used is also horrible from an efficiency standpoint, but cheap to produce.

So it would be best to replace the rotor with a permanent magnet assembly. (shown in hiker's post)   But now you are no better off than if you had started with a motor, which will have better bearings, more iron, and fewer burrs and other defects in the laminations, and a more weather resistant housing.

But if all you can come up with in your austere location is a car alternator, then have at it.   If replacing the armature, make that first. Regardless you will need to wind some test coils and find a way to spin the machine at known RPM, then you can calculate how many turns per phase are needed.

One trick I found was to use lengths of 1/4" (6mm?) PVC plastic tubing in the slots to help keep control of the wire, and to mark which slots to skip, etc.  Make these about 2"/5cm longer than the stack so they stick out 1" or so on each end.  You can also use nylon zip ties to keep one set of coils (phase) in place while you are working on the next.

After winding, you need to lace and varnish the wire so vibration doesn't eat through the insulation.  I used some spray stuff the motor rewinding shop sold me (they no-bid the rewind).  I suspect polyurethane varnish would work as well.