1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

alternator upgrade issues

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Old Jun 1, 2014 | 10:09 PM
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rotor motor 85's Avatar
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From: Hamilton ohio
alternator upgrade issues

So i have been working on doing a taurus alt upgrade on my GSL-SE and I know electrical very well. I have used the search and followed every wiring diagram i can find and there are many. They all say the same things when it comes to wiring and thats how it is hooked up.

https://www.rx7club.com/attachments/...stall-copy-jpg

B+ from alt hooked directly to battery

A wire hooked to B+

S wire hooked to taurus alt stator spot and unchanged from factory

I wire hooked to Black wire / White stripe

now i also have my battery relocated to the storage bin all wiring was done with thick 2 gauge wire and has been grounded to bin frame and drivers side seat bolt.


My issue is this if i take a multimeter and go to the back of the alt i get 13.8 volts.
If i go to the battery while running i get 13.8 volts but my stock gauge says 11 volts. So I thought maybe the stock gauge was faulty but my battery keeps dying.
I have tried switching to the white wire on the alt no change tried re grounding no change.

Please help me figure this out I'm out of ideas.
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Old Jun 1, 2014 | 10:44 PM
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Akagis_white_comet's Avatar
Hey...Cut it out!
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The GSL-SE is wired just like the S4 as shown here:


A Terminal: goes to Battery Positive terminal, NOT the Alternator output post
S Terminal: Loops back to Stator
I Terminal: goes to Ignition-switched 12v

What the diagram you used is doing is making the alternator behave like a one-wire one, which undermines its abilities by sensing voltage at the output post instead of at the battery. There is always a little bit of voltage drop between the two, and you want the alternator to see what the battery sees. Since your battery is relocated, the A Terminal should be connected to the main delivery cable, as close to the battery's positive terminal as realistically practical. My car has a dedicated 12v+ bus bar to facilitate this, which conveniently doubles as a jumpstart point.
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Old Jun 1, 2014 | 10:51 PM
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rotor motor 85's Avatar
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From: Hamilton ohio
Originally Posted by Akagis_white_comet
The GSL-SE is wired just like the S4 as shown here:


A Terminal: goes to Battery Positive terminal, NOT the Alternator output post
S Terminal: Loops back to Stator
I Terminal: goes to Ignition-switched 12v

What the diagram you used is doing is making the alternator behave like a one-wire one, which undermines its abilities by sensing voltage at the output post instead of at the battery. There is always a little bit of voltage drop between the two, and you want the alternator to see what the battery sees. Since your battery is relocated, the A Terminal should be connected to the main delivery cable, as close to the battery's positive terminal as realistically practical. My car has a dedicated 12v+ bus bar to facilitate this, which conveniently doubles as a jumpstart point.




Ok I understand thank you for clearing that up i will straighten that out tomorrow and let you all know how it goes. Thanks Akagis for the prompt and detailed response.
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Old Jun 2, 2014 | 02:03 PM
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From: Hamilton ohio
alt

That worked thanks again Akagis it now holds charge just fine.
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