Another Alternator/Battery Thread!!!
Thread Starter
Racer
Joined: Sep 2015
Posts: 265
Likes: 25
From: Houston Texas
Another Alternator/Battery Thread!!!
Morning everyone,
I thought it might be of value to do a thread tracking progress as I chase down a charging issue with my Vette.
Backstory:
I don't get to drive her very often but yesterday was one of those days where I got to take her out. After running an errand, I noticed the volt gauge on the dash was reading lower than normal and sweeping between 12 and 13 volts. Also, the car seemed a tad sluggish but then it was 103 outside so...IAT can really kill power. I went ahead and ran by Autozone to have them do a quick check of the battery and alternator and got the following:
1) Battery read 12.6V at the terminals
2) Alternator was putting out between 13.1 and 13.4V read off the positive post on the back face of the Alternator.
Autozone guy says, "the alternator is on it's way out".
Came home and did some research on the forum, found alot of recommendations to check the wiring running to the starter as people have had issues with damage related to Long Tube headers. A quick visual inspection hasn't revealed any obvious heat damage as all the cable shielding looks pristine. Also, I couldn't see any signs of corrosion or loose connections at the starter.
Got up this morning, went down to Autozone and ordered the AC Delco alternator (Valeo manufactured for AC Delco, reman as new is not available). Also picked up a multi-meter to do further diagnostics.
Figure the plan will go something like this:
1) Diagnostics
2) If it is the alternator, will be swapping it out this weekend with the replacement unit and then having the original refurbished locally.
3) If it is the wiring, will need to get more info on how to make that repair/replacement.
For reference, the car is a 2003 50th AE. Auto. 14k miles and some change.
Wish me luck!
I thought it might be of value to do a thread tracking progress as I chase down a charging issue with my Vette.
Backstory:
I don't get to drive her very often but yesterday was one of those days where I got to take her out. After running an errand, I noticed the volt gauge on the dash was reading lower than normal and sweeping between 12 and 13 volts. Also, the car seemed a tad sluggish but then it was 103 outside so...IAT can really kill power. I went ahead and ran by Autozone to have them do a quick check of the battery and alternator and got the following:
1) Battery read 12.6V at the terminals
2) Alternator was putting out between 13.1 and 13.4V read off the positive post on the back face of the Alternator.
Autozone guy says, "the alternator is on it's way out".
Came home and did some research on the forum, found alot of recommendations to check the wiring running to the starter as people have had issues with damage related to Long Tube headers. A quick visual inspection hasn't revealed any obvious heat damage as all the cable shielding looks pristine. Also, I couldn't see any signs of corrosion or loose connections at the starter.
Got up this morning, went down to Autozone and ordered the AC Delco alternator (Valeo manufactured for AC Delco, reman as new is not available). Also picked up a multi-meter to do further diagnostics.
Figure the plan will go something like this:
1) Diagnostics
2) If it is the alternator, will be swapping it out this weekend with the replacement unit and then having the original refurbished locally.
3) If it is the wiring, will need to get more info on how to make that repair/replacement.
For reference, the car is a 2003 50th AE. Auto. 14k miles and some change.
Wish me luck!
Melting Slicks
Joined: Jan 2009
Posts: 3,275
Likes: 739
From: Miami FL
...I noticed the volt gauge on the dash was reading lower than normal and sweeping between 12 and 13 volts. Also, the car seemed a tad sluggish but then it was 103 outside so...IAT can really kill power. I went ahead and ran by Autozone to have them do a quick check of the battery and alternator and got the following:
1) Battery read 12.6V at the terminals
2) Alternator was putting out between 13.1 and 13.4V read off the positive post on the back face of the Alternator.
Autozone guy says, "the alternator is on it's way out".
Came home and did some research on the forum, found a lot of recommendations to check the wiring running to the starter as people have had issues with damage related to Long Tube headers...
1) Battery read 12.6V at the terminals
2) Alternator was putting out between 13.1 and 13.4V read off the positive post on the back face of the Alternator.
Autozone guy says, "the alternator is on it's way out".
Came home and did some research on the forum, found a lot of recommendations to check the wiring running to the starter as people have had issues with damage related to Long Tube headers...
The voltage reported by the DIC is downstream the ignition switch, therefore it doesn't really indicate how the charging system is performing.
Normally, the alternator's output should be between 13.5v and 14.5v. The reading taken by AutoZone seems a little low. It would be good to check that again, although you mentioned it was really hot when the reading was taken.
Charging voltage dropping a bit (as measured directly at battery/alternator) at high temperatures is normal. When a battery is hot it should be charged at a lower voltage than when it is colder, and the voltage regulator in the alternator has a temperature compensation circuit that provides that adjustment.
Last edited by GCG; Aug 3, 2018 at 11:49 AM.
Thread Starter
Racer
Joined: Sep 2015
Posts: 265
Likes: 25
From: Houston Texas
To troubleshoot a low voltage condition you would need a multimeter to check the voltage drop from the alternator to the battery. Place the multimeter's positive lead at the alternator's output terminal and the multimeter's negative lead at the battery's positive post. This reading shouldn't be more than 0.2v (typically 0.1v or less). If it is more than 0.2v, the connection point at the starter solenoid needs to be checked, as well as the cables in the alternator-solenoid-battery path.
The voltage reported by the DIC is downstream the ignition switch, therefore it doesn't really indicates how the charging system is performing.
Normally, the alternator's output should be between 13.5v and 14.5v. The reading taken by AutoZone seems a little low. It would be good to check that again, although you mentioned it was really hot when the reading was taken.
Charging voltage dropping a bit (as measured directly at battery/alternator) at high temperatures is normal. When a battery is hot it should be charged at a lower voltage than when it is colder, and the voltage regulator in the alternator has a temperature compensationcircuit that provides that adjustment.
The voltage reported by the DIC is downstream the ignition switch, therefore it doesn't really indicates how the charging system is performing.
Normally, the alternator's output should be between 13.5v and 14.5v. The reading taken by AutoZone seems a little low. It would be good to check that again, although you mentioned it was really hot when the reading was taken.
Charging voltage dropping a bit (as measured directly at battery/alternator) at high temperatures is normal. When a battery is hot it should be charged at a lower voltage than when it is colder, and the voltage regulator in the alternator has a temperature compensationcircuit that provides that adjustment.
So I guess the plus side is the wiring harness is not the issue?
So what is my next step? (Multi-meter in hand!)
Melting Slicks
Joined: Jan 2009
Posts: 3,275
Likes: 739
From: Miami FL
Check the alternator's output with a cold engine and with a hot engine to see if it is within range and also how much it is being affected by temperature.
Last edited by GCG; Aug 3, 2018 at 12:05 PM.
Thread Starter
Racer
Joined: Sep 2015
Posts: 265
Likes: 25
From: Houston Texas
Ok,
Next Update:
1) Measured the resistance across the wiring harness from the alternator to the battery, again measuring 0. I am not too surprised as the car has few miles and nothing is visibly damaged on the wiring near the starter.
2) Measured the voltage across the battery posts, car off: 12.6V
3) Measured the voltage across the battery posts, car on: 14.6V at immediate startup leveling down to 14.3V after about 2 minutes.
4) Drove around the block for 10 minutes to bring the car up to operating temp, circa 190F. (have a 180 thermostat if I am not mistaken, aftermarket)
5) Measured the voltage across the battery posts, car on and at running temp: 13.6V
Can this be early indication of an alternator control module on the way out?
What should I be looking at next?
Next Update:
1) Measured the resistance across the wiring harness from the alternator to the battery, again measuring 0. I am not too surprised as the car has few miles and nothing is visibly damaged on the wiring near the starter.
2) Measured the voltage across the battery posts, car off: 12.6V
3) Measured the voltage across the battery posts, car on: 14.6V at immediate startup leveling down to 14.3V after about 2 minutes.
4) Drove around the block for 10 minutes to bring the car up to operating temp, circa 190F. (have a 180 thermostat if I am not mistaken, aftermarket)
5) Measured the voltage across the battery posts, car on and at running temp: 13.6V
Can this be early indication of an alternator control module on the way out?
What should I be looking at next?
