Alternator Harness

Jamie V said:
In my case I have a truck with very low mileage and I’m walking the line of modifying some things to make it more enjoyable to drive but at the same time not modifying anything that can’t 100% totally be reversed with no signs of modification.

I’ve considered running an alternator ground from the back of the alternator down to where the stock ground wire mounts to the frame.
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i removed one of the long hex head screws on the back of the alt on the passenger side nearest the batt and connected the ring terminal there and took the nut off the neg batt post clamp and connected the other ring there. wire can be run along existing wiring and secured. i can remove it and there isn't any permanent changes. however, it's probably not beautiful to look at. i understand your situation.
 
Steve83 said:
My guess is that it's at the normal block ground, forward of the engine mount.

(phone app link)


Did you polish the ring terminal and block face?
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i cleaned it and the terminal ring on the cable extremely well, cleaned out the threaded hole with a tap, cleaned the bolt well and applied conductive grease. i'm not worried about it. everything functions very well.
 
Jamie V said:
I upgraded to a 130amp alternator and it still can’t keep up. With everything on I’m drawing about 120amps and the voltage is down to 12.40v at the battery but 12.75v on the back of the alternator.
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New 200 amp alternator installed (with stock alternator wiring harness) and now with the same test the voltage has gone up to 13.18v at the battery and the amperage has gone down to 114amps.

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I checked the voltage at the back of the alternator and it is 13.53 so right at .35v drop as before (couldn’t take a picture, needed both hands)
 
I think I’m going to run what I have until I find a nice harness to modify then build my “ideal” harness at that point. I’m happy the volts are up and the amps are down a smidge but I’m not 100% happy with the 0.35v drop. I don’t think this will melt the fuseable link at this amperage (to be honest it’s not too often that the fan, AC compressor, headlights and everything are running at the same exact time) so I should be ok for a while. I’m also going to add an alternator ground like I mentioned before at the same time. I don’t think I really need it but it can’t hurt.
 
Your current went down because your voltage went up. Ohms law watts (load)=E*I. Load stayed the same and since voltage went up current dropped.
 
Knew it would go down when the volts went up. I just don’t like the voltage drop through the stock harness.
 
bobwhite said:
i just happened to notice you have an alt case ground wire listed in your blue-lettered build list.
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I installed Ed's alternator and battery cables, fan controller, T-bird e-fan, and upgraded to a 130 amp alternator. IIRC, I performed some underhood detailing, and wanted to ensure I had a good alternator ground to keep my charging system happy.
 
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