280zx alternator using 75 280z external voltage regulator?

[Akira]

Hello HybridZ!

 

When I first got my 75Z a while back, I planned to do the 280zx alternator swap. Interestingly, the previous owner installed a 60amp alternator from a 280zx, but I noticed that the external voltage regulator was still there on the 75 and none of the wires were spliced like the atlanticz tutorial. Is it possible that the 280zx alternator is running the external voltage regulator of the 75 instead of it's own internal voltage regulator?

 

Any help would be appreciated!

 

Thanks!

Edited December 11, 2011 by Akira

[beermanpete]

Possible? Yes, but it would be a lot of work to modify the internals correctly. There is no obvious advantage for this mod. It is more likely that the internal regulator is still in place and functioning. Whoever installed the newer alternator probably modified the external wiring to make it work and simply did not bother to remove the original regulator which is now not doing anything.

[BluDestiny]

Is your volt gauge working properly?

[Akira]

Thanks beermanpete and bludestiny for the help!

 

Ahh yes, I had to cut back the harness more and it seems the "L" (lamp) on the alternator has a spliced wire that may be going to a switched 12v source. The "S" (sense) is connected to the BAT on the alternator.

 

The car runs fine. Runs even better after the dizzy and msd upgrade. All electronics and gauges work. The volt gauge seems fine. Only weird thing is when I turn on my car lights, I see the gauge move a little towards the right. I would think it would move towards the left since it is drawing more energy?

 

Anyways, from what I can tell now, the external regulator is sitting there connected and getting power, but it is not wired to the alternator. So I'll go ahead and disconnect that when I get back home and see what happens.

Edited December 11, 2011 by Akira

[NewZed]

I've seen reports of it being done by accident before. Can't remember the details, but there was a problem with it, event though the alternator was charging. Either the engine would keep running when the key was off, or the voltage was not regulated, or there was a battery drain with the key off. You might check with a voltmeter before you go much farther, high voltage can cause some damage. Don't forget to rev the engine to see what the output is above idle. The Z alternators barely put out enough amps at idle to supply all the loads.

[Akira]

Thanks NewZed!

 

Well, the car seems to be running fine without the external voltage regulator connected. I measured 12.38v between the battery terminals when the car was off. At idle and with a load of 3-4k rpm's, it was at 13.65-13.69v. At the "S" (sense) and "L" (Lamp), they measured 14.06-14.10v between idle and a load of 3-4k rpm's. Hopefully, that sounds right.

[Akira]

After doing some more searching, I noticed that the "L" lamp should only be getting power when cranking. It seems that I'm getting power even after cranking. The Z has been like this for at least a year and haven't had any issues (knock on wood). However, maybe it would be smarter to redo my wiring like the atlanticz tutorial?

[beermanpete]

Thanks beermanpete and bludestiny for the help!

 

Ahh yes, I had to cut back the harness more and it seems the "L" (lamp) on the alternator has a spliced wire that may be going to a switched 12v source. The "S" (sense) is connected to the BAT on the alternator.

 

The car runs fine. Runs even better after the dizzy and msd upgrade. All electronics and gauges work. The volt gauge seems fine. Only weird thing is when I turn on my car lights, I see the gauge move a little towards the right. I would think it would move towards the left since it is drawing more energy?

 

Anyways, from what I can tell now, the external regulator is sitting there connected and getting power, but it is not wired to the alternator. So I'll go ahead and disconnect that when I get back home and see what happens.

 

 

After doing some more searching, I noticed that the "L" lamp should only be getting power when cranking. It seems that I'm getting power even after cranking. The Z has been like this for at least a year and haven't had any issues (knock on wood). However, maybe it would be smarter to redo my wiring like the atlanticz tutorial?

 

The "L" terminal needs to go to a key-on voltage source to energize the alternator. It sounds like you have this already so you should be fine. The only thing I suggest is to verify the connection is not through a low resistance path. It seems to need a resistive path to limit the current (the lamp does this in the ZX). A low resistance connection could allow the loads in the car (headlights, etc.) to drag down the voltage needed for the field winding, causing low alternator output and possibly damaging the diode-trio for the field winding. If there is no resistance you should consider adding a small resistor or a warning light to the circuit.

 

The "S" terminal is suppose to be direct so that is ok.

 

Your comment about the voltmeter reading increasing when turning on the headlights indicates the voltmeter is measuring the voltage closer to the alternator than the "S" terminal does. It probably does not matter, especially since you indicated the car is working fine and has done so for a long time. It is possible this is typical behavior for the 280Z or the 280ZX. I do not know, perhaps others who are familiar with this will comment. The "solution", should you want to bother, would be to rewire the charging system and voltmeter to sense and measure the voltage in the same place.