alternator wiring

andy1020 · Unread post by **andy1020** » 04 Mar 2008, 21:29

Hi guys,
I know you'll be able to help me here... I used to work as a mechanic, but need a bit of specific knowledge here.

I'm doing a project with some school kids making a generator from an alternator & exercise bike... it's geared up to give decent rpm and so on...

I got whatever alternator the scrappy had handy on the shelf: from a Clio 1.2 don't know what year. Probably the same alternator on a few small engine french cars.... 70Amp, mitsubishi label.

I need to know the wiring, as I'm not getting any voltage from it. I figure it needs a small feed to power the electromagnet before it can give a voltage??

There's a big red lead: +ve feed, no problem. Casing is ground I guess, fine.
Question is the 2 little wires (white & green i think), connected via a black connector plug to the back of the alternator. Does anyone know what they're connected to?? Do they provide some sort of feed so that it can then give a voltage??

help appreciated,
Andy.

Unread post by **CitroJim** » 04 Mar 2008, 21:39

Hi Andy,

Welcome to the forum

You're nearly there. One or even both of those small wires need +12V to excite the alternator. One will be wired to provide +12V via the ignition light so wire one of the small terminals to the battery positive via a small 12v dash lamp bulb and it should light up and as soon as the alternator is up to speed, go out just as you'd expect. If this fails, try the other small terminal or both at the same time. One or the other may need to be earthed. Play around until it works. feeding +12V onto the small terminals via a small bulb will do no harm whereas putting 12V directly to those terminals might.

Many alternators stop charging if the ignition lamp blows. That can cause a bit of headscratching the first time you see it!

Sorry I can't be more specific. I'm a Citroen person

How about putting an ammeter in the big positive battery lead so the kids can see the battery being charged...

andy1020 · Unread post by **andy1020** » 04 Mar 2008, 21:42

great , thanks.
Also, presume it has a built in regulator in the alternator?

Unread post by **CitroJim** » 04 Mar 2008, 21:53

andy1020 wrote:Also, presume it has a built in regulator in the alternator?

Oh yes

Long gone are the days of external regulators, thank goodness!