wiring up a smart regulator externally.

[Birdseye]

I have had a number of alternator regulator failures which I believe are down to excessive engine box heat. But I have a sterling digi regulator which is more sophisticated that the simple voltage limit jobbies attached to my alternator. So the obvious next step is to wire up the Sterling regulator externally to my alternator without having a normal regulator in place. I tried it this week and failed and unfortunately the person I spoke to at Sterling wasnt willing to talk me through what was needed.

There are 4 terminals on my alternator - the main positive B+, the main negative B- the tacho wire and the D+ that gets the feed from the instrument panel. There are two brushes in the old failed regulator and the alternator is a negative field control one. What I am proposing is to use the failed built in regulator simply as a brush holder. So it seems to me that the way to wire up the regulator as as follows:

1/ the two black wires from the regulator go to B- along with the main engine / battery negative
2/ the brown wire goes to the D+
3/ the red sensor wire goes to the the B+ along with the main engine / battery positive because thats where the voltage we need to control is and thats the function of the red sensor wire.
4/ the yellow wire that switches and powers the Sterling regulator goes to the ignition switch
5/ the white control voltage wire goes to the brush for the negative field control.

Two bits of this scenario concern me. They are

1/ where does the other brush get its feed of 14v or so from? Simple connection to B+?
2/ I dont understand how the D+ functions. Is it simply the alternator output voltage that triggers the alarms and lights if below 12.7 or whatever? In that sense is it the same as B+?

Yes I know I could just go off and spend £340 on a new Volvo alternator ( or £112 on a pattern one) but where is the fun in that? And in any case I want to try a regulator outside the heat of the engine box

In case there are any leccies out there who are bored enough to puzzle through this, the Sterling reg instruction booklet is at http://www.sterling-power.com/images/downloads/alt regulators/AR12V.pdf

 

[pampas]

years since I fitted one of these units, designed so that if the "Booster reg fail or if you switch it off the alternator reg takes over its old job.
You will need the old regulator or a new one in order to use as brush holders. new one preferably. when running the alternator should stay fairly cool if not you need more cooling air in the engine bay.
D+ comes of the ignition through the warning light (If the grey cell are correct) B+ is the output direct to the battery as is B-
Your alt is Hitachi? read carefully the instructions, I remember something about seeking their advice concerning connecting to this type.

 

[VicS]

Two bits of this scenario concern me. They are

1/ where does the other brush get its feed of 14v or so from? Simple connection to B+?
2/ I dont understand how the D+ functions. Is it simply the alternator output voltage that triggers the alarms and lights if below 12.7 or whatever? In that sense is it the same as B+?

The other brush is fed internally from B+

D+ is the field current input to the regulator from the field diodes. If an alternator has an external regulator the output from the field diodes my be designated 61.
The indicator/warning light is connected to 61/D+

When you first switch on there is no field current available from the field diodes so current flows to the regulator via the warning light from the ignition switch. The warning light therefore glows.
Once the alternator is generating and the volts output from the field diodes approaches the battery volts current through the warning light diminishes and it ceases to glow.

Are you sure you can operate the Sterling regulator without the normal alternator regulator?


Correction: the other brush is fed from the field diodes not from B+

 

[Birdseye]

Thanks Vic. The Sterling manual implies that you can use it stand alone and indeed one of their more helpful staff said you could do so.

I am still not understanding the D+ terminal. B+ and B- are the two ends of the stator rectified by the diodes. OK? The regulator senses the output voltage from B+ and adjusts the supply voltage to the rotor accordingly, in my case by lifting the negative above zero whilst the positive stays at B+ voltage. OK? So where is the D+ tapped into this system that it gets a different voltage - I understand the bit about the threshold voltage activating the warning light, just not the bit about " field current available from the field diodes so current flows to the regulator via the warning light from the ignition switch". I had always thought that the ignition switch would provide the initial exciter voltage to the rotor via the regulator, this would cause the rotating alternator to generate volts which the regulator would then trim if necessary and the ignition light wopuld be looking at the difference between battery voltage and B+ voltage.

Are there special field diodes? Why do you need diodes serving the rotor if its fed with battery dc volts?


STOP PRESS! A poster has sent me a copy of the alternator handbook. I'm right in basic principles but the real life application of a regulator is a bit more complicated than the above for all sorts of reasons. I think I'm going to have to do a bit of studying and even then I might have problems because I dont know exactly how the built in regulator works on my alternator and therefore what the external one needs to mimic.

 

[pvb]

STOP PRESS! A poster has sent me a copy of the alternator handbook. I'm right in basic principles but the real life application of a regulator is a bit more complicated than the above for all sorts of reasons. I think I'm going to have to do a bit of studying and even then I might have problems because I dont know exactly how the built in regulator works on my alternator and therefore what the external one needs to mimic.

As I understand it, if you install the Sterling in accordance with the instructions, it operates in tandem with the alternator's own regulator and, if either were to fail, the other one would work. In that case, just install the Sterling unit as instructed, with your failed regulator in place, and it should work as an external regulator. Perhaps ask Sterling if this is indeed the case.

 

[Cantata]

As I understand it, if you install the Sterling in accordance with the instructions, it operates in tandem with the alternator's own regulator and, if either were to fail, the other one would work. In that case, just install the Sterling unit as instructed, with your failed regulator in place, and it should work as an external regulator. Perhaps ask Sterling if this is indeed the case.

I think that's pretty good advice. I've installed a couple of these and, following the instructions, they simply work, without any detailed knowledge required on my part.

 

[VicS]

Thanks Vic. The Sterling manual implies that you can use it stand alone and indeed one of their more helpful staff said you could do so.

I am still not understanding the D+ terminal. B+ and B- are the two ends of the stator rectified by the diodes. OK? The regulator senses the output voltage from B+ and adjusts the supply voltage to the rotor accordingly, in my case by lifting the negative above zero whilst the positive stays at B+ voltage. OK? So where is the D+ tapped into this system that it gets a different voltage - I understand the bit about the threshold voltage activating the warning light, just not the bit about " field current available from the field diodes so current flows to the regulator via the warning light from the ignition switch". I had always thought that the ignition switch would provide the initial exciter voltage to the rotor via the regulator, this would cause the rotating alternator to generate volts which the regulator would then trim if necessary and the ignition light wopuld be looking at the difference between battery voltage and B+ voltage.

Are there special field diodes? Why do you need diodes serving the rotor if its fed with battery dc volts?


STOP PRESS! A poster has sent me a copy of the alternator handbook. I'm right in basic principles but the real life application of a regulator is a bit more complicated than the above for all sorts of reasons. I think I'm going to have to do a bit of studying and even then I might have problems because I dont know exactly how the built in regulator works on my alternator and therefore what the external one needs to mimic.

If the Sterling manual says you can use the Sterling regulator without the alternator's own regulator and Mr Sterling has confirmed it fair enough. I missed that when I looked at the manual but I think I have read it there previously.

Enjoy the alternator handbook. It explains it all so it should all become clear to you. The field diodes are referred to as the "diode trio" and are usually simply part of the main diode assembly. They supply the field current. The warning light circuit only supplies the initial excitation to get it started.

For anyone else interested the it can be found ( at least an old edition ) at http://www.motoren.ath.cx/menus/electrical.php together with the original edition of the 12volt Handbook.