Archived Alternator hookup

[monkfarm]

Anybody know what voltage those plug in wires on the back of the stock alternator are (dark blue and dark green). My aftermarket shop manual says one (dark blue ) goes to the powertrain module (which I believe is 4 volts). That isn't 4 volts coming off the alternator is it??

I don't know if I should be posting this here, but I have some help, and we are trying to get a Neese- Deville 140 amp alternator installed and I don't want to fry the computer. . .

 

[K5IP]

Dean,

Sorry I do not hav my manual with me, so I don't know the wire color code, but there are two smaller wires which provide current to the field winding of the alternator. One provides the full battery voltage via the alternator shut down relay(12. 5vdc). The other connection ties the other end of the field winding back to ground through a variable resistance established by the computer. If you see 4vdc on one winding, this is the return side back through the computer and it sounds like things are working right.

12. 5vdc-4vdc means you have 8. 5 vdc across the field winding, enough to provide a reasonably good charge rate.

The battery voltage side will remain fixed at the battery voltage as long as the auto shutdown ralay is engaged.

The other side (4vdc) will change as the pcm commands different battery charge rates. The lower the return side voltage, the higher the differental voltage across the field, and higher resulting charge rate. Quick lesson, hope it helps.

Rog

 

[monkfarm]

Thank you Roger, and this does confirm what I thought might be the case. So I'm still wondering what to do with those two wires on the new Neece-Deville. There is 3 connections for the stator, (presumably for hooking up a tach to a mechanical engine (without the computer). but I don't know if this is appropriate for hooking up the 4 volt. (I don't want to send too much voltage into the brainbox.

 

[K5IP]

Sorry Dean,

I just don't have enough info to help.

You should be able to get info from Neece-Deville, perhaps on line, that will help.

Generally, however, the stator is connected internally to the recifier bridge, and from there to the big terminal that has the high output current on it.

Why there are connections to it, I do not understand. (be aware that the field is the rotating element)

I'll try to look something up and if I find anyhthing, I'll pm you.

Rog

 

[monkfarm]

I really appreciate your response, I will try online to Neece-Deville. Appreciate it!!