Chevelles.com banner

1 - 20 of 41 Posts

·
Registered
Joined
·
33 Posts
Discussion Starter #1
Well pulled the alternator which was harnessed into the 4 terminal transistorized VR which I assume was defective as the Field terminal 1 was continuos with the always hot Battery terminal 3. Took it to Napa where they stuck it on their tester and it only gave 11 volts and the error message "Never turned on". Lo and Behold, it was actually an internally regulated 37 amp. Traded it in for one that tested on their machine to give 16 volts, and "Good" Asked em, "Okay so if it's internally regulated then why does it still have the two pole socket marked F [field] and R [relay], why isn't there just the output wire and that's it?" Nobody had a clue. So then took a cruise over to Fisher Chevrolet Service Dept. and the team manager said just jump the "R" terminal to the output terminal, and run the "F" terminal to the ignition, either at the + side of the coil or through the harness.

So has anyone actually hooked it up this way and does it indeed work? It seems that if I hook the field to the hot side of coil that the resistance current limit wire from the ignition to the coil is just going to drop more voltage because of the extra load through the field coil. Things that make you go Hmmmm??
 

·
Registered
Joined
·
1,413 Posts
The F connects to the wire coming from the altnerator light in the dash. Should be a brown wire going to the #4 terminal on the regulator.

I don't know if I'd trust the test method or the parts store doing it. An internally regulator alternator should regulate the voltage when it's tested and the regulated voltage should not go above about 14.5V. An externally regulated alternator would be tested by just applying an unregulated voltage to the field and then the output voltage would also not be regulated and therefore able to rise to a much higher level. Easy way to tell is the connector. If the terminals go like || then it's external and if they go like -- then it's internal.

http://www.chevelles.com/techref/ftecref14.html

Peter
 

·
Registered
Joined
·
3,091 Posts
Yep, I run all mine that way except I don't run the ignition wire. Mine are all 1 wire only. You have to "blip" the throttle on first start up to get the alternator charging.
 

·
Registered
Joined
·
7,762 Posts
But isn't the alternator running wide open then? What holds it within regulation? Your input is more than welcome, but it's better to run the one-wire as a 3-wire.
 

·
Registered
Joined
·
7,762 Posts
Three wire means that there are 3 wires tied to the alternator. The large B+ on the rear and the 2 out of the connector. What Dennis decribes is the way some newer aftermaket units run. The field is self excitable by increasing the RPM to start them. Doesn't work that way on an internally regulated GM SI style alternator. Need the field and the sense line hooked up.
 

·
Registered
Joined
·
7,762 Posts
Originally posted by dennis68:
Yep, I run all mine that way except I don't run the ignition wire. Mine are all 1 wire only. You have to "blip" the throttle on first start up to get the alternator charging.
I mis-spoke. You did say you tied the sense line to the output. Great if you have a voltmeter installed to watch it.
 

·
Registered
Joined
·
33 Posts
Discussion Starter #8
Okay so how do I determine if this is a GM/ SI alternator?????? Then assuming it is so, WHERE do I connect the "R" wire and the "F" wire????? On the schematic I have, F to the F terminal on the external regulator and R to terminal 2 of same regulator. Even though there is an internal regulator in this alternaor, do I still use an external regulator??????? I need to confirm what has worked for others so that this rebuilt doesn't get fried. Thanks
 

·
Registered
Joined
·
7,762 Posts
Did you have a chance to read what Peter wrote?

"Easy way to tell is the connector. If the terminals go like || then it's external and if they go like -- then it's internal.

He's refering to the connector pin blades in the alternator. All Delco DM (external) and SI (internal) alternators are set up this way.
 

·
Registered
Joined
·
5,182 Posts
I gotta wade in here with an observation. I have been fooling around with my alternator conversion, actually I have NOT been working on it, for a long time. I jump in here and read this stuff and here is an observation.

There is soooo much info on here and some of the posts are so vague, except for responses by a few people in the know, that I cannot believe thee are not more FIRES or dead batteries than apparently there are.

Info about CS alts gets transposed in posts about SI alts...today someone in the process of doing a swap who already has an alt asked "Well how do I know what type it is", it appears that some of these "Just put a wire from here to there" answers result in the alternator being on all the time. One wire information gets interlaced with info about 3 wire...it just goes on and on. It even appers to me that one wire alts (based on data on the MAD and other manufacturers tech sites) are not good for street driven cars in fact they were designed for FARM equipment.

I mean to say that it would seem with all the work going into these cars that people would research what they are doing a little better than it appears they do. The money and efort tied up in these cars seems to mandate care in terms of electrical problems that can lead to BAD NEWS.

Just my $.02. Not criticizing anyone just mystified about this topic and how people approach this conversion.
 

·
Registered
Joined
·
3,091 Posts
SI alternator is internally regulated, none of the wires going in or coming out of the case have anything to do with charging output. It is all done internally. One post is for battery output(large lug), the other 2 are charge sense(gauge) and ignition feed(turn on). If you link the ignition feed to the battery lug, the alt is "on" all the time. Quick rev and it starts to charge. Works great, clean and easy installation. Like I said, I have been running this way a several different cars for better than 10 years, all daily drivers. No problems.
 

·
Registered
Joined
·
7,762 Posts
Originally posted by dennis68:
SI alternator is internally regulated, none of the wires going in or coming out of the case have anything to do with charging output. It is all done internally. One post is for battery output(large lug), the other 2 are charge sense(gauge) and ignition feed(turn on). If you link the ignition feed to the battery lug, the alt is "on" all the time. Quick rev and it starts to charge. Works great, clean and easy installation. Like I said, I have been running this way a several different cars for better than 10 years, all daily drivers. No problems.
Well, that may work but it doesn't hold the alternator output voltage stable. That's what the sense line to the regulator does. Not the way I'd hook it up. The alternator voltage will vary under load changes without the sense line attached somewhere.
 

·
Registered
Joined
·
3,091 Posts
John, when there is no voltage at the sense wire the regulator goes to the charge lug to monitor voltage level and determine field strength, otherwise if you lost that line, the alt. would full field and blow up batteries and all kind of fun stuff. The alt in my current ride is 8 years old and the battery is at least 10 years old. I took it out of a customers car and filled/recharged it, she wanted a new one so I kept it, 6 years ago. All is working great. I don't know where the problem lies.
 

·
Registered
Joined
·
7,762 Posts
Originally posted by dennis68:
John, when there is no voltage at the sense wire the regulator goes to the charge lug to monitor voltage level and determine field strength, otherwise if you lost that line, the alt. would full field and blow up batteries and all kind of fun stuff. The alt in my current ride is 8 years old and the battery is at least 10 years old. I took it out of a customers car and filled/recharged it, she wanted a new one so I kept it, 6 years ago. All is working great. I don't know where the problem lies.
The purpose of an alternator regulator is to control the battery charging current from the alternator. The charge level of the battery is proportional to the battery voltage level. The regulator monitors the battery voltage level. When the battery has attained the proper charge the charging current is switched off. The charging current is controlled by switching the alternator field current on and off.
I guess I’m not seeing something. If the sense line, the wire that monitors the alternator output/battery input isn’t used, how is the alternator field controlled? I’m not suggesting doing anything differently that the method that the SI alternators were originally installed in the car. Is the charge lug you refer to the rear B+ terminal? If so, I agree but a jumper wire needs to be installed there. That's what's used on the factory wiring.
BTW, great discussion and maybe I’ll learn something. Beats working on a boring report.
 

·
Registered
Joined
·
3,091 Posts
The sense line is probably named improperly as it does not really sense anything for the alternator, it is for gauge/light, or warning of whatever type. The ign. feed is the only input to the alt. and it is just tell the alt. to turn off so there is no chance of battery discharging. The alt. knows of current state of charge by simply "looking" at the main charge line, it is connected in some way directly to the battery.
 

·
Registered
Joined
·
3,091 Posts
Yeah John the charge line is the B+ on the rear of the case. I do have a short jumper wire, about 3", from the ignition feed to the charge line.
 

·
Registered
Joined
·
33 Posts
Discussion Starter #17
Okay John M. I have Dennis' opinion of how to hook it up, and you v'e stated that you wouldn't do it that way. So then how would you do it??????????????????????????????????????????????
??????????????????????????????????????????????????????????????????????????????????????
 

·
Registered
Joined
·
33 Posts
Discussion Starter #18
PS the terminals are in a single line and geometrically parallel to the front and rear of the unit so according to Dennis it is internally regulated.
 

·
Registered
Joined
·
7,762 Posts
Originally posted by dennis68:
The sense line is probably named improperly as it does not really sense anything for the alternator, it is for gauge/light, or warning of whatever type. The ign. feed is the only input to the alt. and it is just tell the alt. to turn off so there is no chance of battery discharging. The alt. knows of current state of charge by simply "looking" at the main charge line, it is connected in some way directly to the battery.
There is a true sense line coming out of the alternator. It’s not really mis-named. The idiot lamp doesn't go on the sense line. The switch line is closer to an excitation line. Dug up this.
http://members.1stconnect.com/anozira/SiteTops/energy/Alternator/alternator.htm
 
1 - 20 of 41 Posts
Top