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Electrical 3G alternator over charging

  • Thread starter Thread starter sav22rem22
  • Start date Start date Jun 15, 2023

sav22rem22

5 Year Member
Feb 6, 2020
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North Carolina
Jun 15, 2023
#1
  • Jun 15, 2023
  • #1
So I decided to throw on a 3g 130 amp sve alternator at the same time as my heads/cam job a month ago. I wired it up exactly as shown in the LMR video which I’ve learned was a mistake and that I shouldn’t have used both the bigger 4 gauge and the factory power wires with ring terminals on them.

The issue I’m having is that the voltage at the battery is 14.9 volts at idle which seems excessively high. I’ve tested the yellow/white voltage sensing wire resistance to the green wire at the solenoid and it ohms out to about 1 ohm. All grounds in the engine bay have been re done/ cleaned while I was doing the heads and cam job. All lights on the car flicker and pulse. I have a quarterhorse on the car and when datalogging with binary editor you can see the voltage spiking rapidly between like 14 and 14.6 which would explain the pulsing I assume.

My question to you all is, what diagnostic steps should I take next to rule out the alternator itself being bad and not just a bad voltage regulator? Any wiring tests I can do? I have since removed the factory power wires off of the alternator lug and taped them up and set them aside.
 

Blown88GT

Founding Member
Nov 13, 1999
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Palm Beach Gardens, FL
Jun 16, 2023
#2
  • Jun 16, 2023
  • #2
You will need an 0-scope to look at the alternator output. Excessive ripple will indicate a bad alternator diode.
 

mikestang63

SN Certified Technician
Aug 27, 2012
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Jun 16, 2023
#3
  • Jun 16, 2023
  • #3
where did you get the alternator from? I would bring it to Vatozone or Advanced Auto Parts and have them test it for free. Then you know if that is the problem or not.
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
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Jan 4, 1985
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Jun 16, 2023
#4
  • Jun 16, 2023
  • #4
 
Reactions: General karthief

sav22rem22

5 Year Member
Feb 6, 2020
397
86
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North Carolina
Jun 17, 2023
#5
  • Jun 17, 2023
  • #5
mikestang63 said:
where did you get the alternator from? I would bring it to Vatozone or Advanced Auto Parts and have them test it for free. Then you know if that is the problem or not.
Click to expand...
Got it from LMR a couple of months ago. That is a good idea I’ll have to make sure my local parts stores do that considering they’re a little janky in my small town lol.
 

sav22rem22

5 Year Member
Feb 6, 2020
397
86
48
North Carolina
Jun 17, 2023
#6
  • Jun 17, 2023
  • #6
Noobz347 said:
Click to expand...
Great video. Will definitely do that today. Here’s hoping it doesn’t fail that test because this would make the second bad LMR part I’ve gotten within a couple months timeframe.
 
Reactions: Potomus Pete
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