# Alternator as motor



## gavpop (Jun 13, 2014)

Hi,

This is my first post and I'd like to introduce myself.
I'm Gavin and I'm currently working on a DIY Solar Power Lawnmower...I know, slightly off topic, but couldn't find a more suitable forum.

Anyways - I need a powerful motor for my project.
DC motors in the power range I require are hugely expensive, so I've started looking at Alternator conversions.

I've bought myself a cheapo alternator off Ebay and cracked it open.
From what I've read, I'll need three connections off the windings, but my alternator has four. I suspect this alternator isn't suitable, but hoping someone with more knowledge can confirm or deny this?

Here is a pic -


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## arklan (Dec 10, 2012)

this is what i know about car alts and it isnt much

there should be 3 wires kinda bunched together and 1 thick wire which goes to the battery.
the 3 wires go to the voltage regulator which controls how strong the field windings should be; weak if the battery is near the top, strong if the battery is low etc etc.
its also earthed to the frame so it returns to the battery through the chassis.
the 3 regulator wires suggest that its 3 phase.
this is a pretty typical setup in a car alt

http://www.diyelectriccar.com/forums/showthread.php/car-alternator-used-motor-mode-330.html

https://au.answers.yahoo.com/question/index?qid=20100531050522AAIpNAi

http://www.fieldlines.com/index.php?topic=146394.0

something else u could do so u dont need such a powerful motor.
make it work the same as a wipper snipper, they have smaller engines than lawnmowers and cut grass pretty well

buying a ready made dc motor is gonna be your best bet, or go to the rubbish tip and find an old treadmill or something like that
u could also try a 4wd wrecker and see if they have any winch motors


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## major (Apr 4, 2008)

gavpop said:


> I'll need three connections off the windings, but my alternator has four.


From the photo, the 2 on the left have a pair of magnet wire leads soldered together and the 2 on the right have a single magnet wire. I suspect the two singles are parallel windings and should be joined to make the third phase. You can verify that by connecting a scope to the windings and rotating the machine with about 5 or 10V on the field via the slip rings.

In the middle is the node for the Y connection. It has 6 doesn't it?


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## poprock (Apr 29, 2010)

What happened to the listed post by Major? It isn't showing on my page.


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## arklan (Dec 10, 2012)

major said:


> From the photo, the 2 on the left have a pair of magnet wire leads soldered together and the 2 on the right have a single magnet wire. I suspect the two singles are parallel windings and should be joined to make the third phase. You can verify that by connecting a scope to the windings and rotating the machine with about 5 or 10V on the field via the slip rings.
> 
> In the middle is the node for the Y connection. It has 6 doesn't it?


here it is


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