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Discussion Starter #1 (Edited)
This morning (a cool morning), about 10 minutes into a drive, I had the red battery light and the "Alternator" warning pop up on the dash display. It turned off a few seconds later, so I kept driving, but it popped up again shortly thereafter. I shifted my aeroforce over to voltage (which is good for a rough idea, not overly accurate for 'at the battery' voltage), and I could watch how it was triggering. It looked like the battery would be charging at around 13.6V, then suddenly drop to about 11.4V or lower and the alternator light would pop up. Then the voltage would pop up to ~12.8V, the light would go out, then the voltage would rise to around 13.6V again since I assume the system thought it should be in the lower voltage 'maintenance' voltage. There was never a "service charging system" or "battery saver" warning.

I'm assuming that a voltage in the low 11's while the alternator is supposed to be charging is what is causing the light to pop up. What I'm trying to figure out is if I'm having an intermittent shorting battery cell or simply a failing alternator. The battery is only a couple of months old and the startups have been nice and strong, but stranger failures have happened.

Any thoughts? Others have had similar issues, but it wasn't clear to me what was ultimately their issue.
 

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That display is exactly how my car started its bad news info. It quickly became worse, when a big lighting bolt was displayed in the DIC. A new OEM alternator solved the problem. I'm positive the internal voltage regulator failed. I did buy a new regulator an installed it into the original alternator. But I'll only know the outcome from doing that rework, if an when I have to replace it again. Not sure if all models incorporated that lighting bolt display, but it sure got your attention that you were in trouble.
 

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FYI I had the same problems and warnings. Turned out my battery and alternator needed replacing.
Seems to be a fairly common problem.
Alternator - GM part # (92191127)
 

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That display is exactly how my car started its bad news info. It quickly became worse, when a big lighting bolt was displayed in the DIC. A new OEM alternator solved the problem. I'm positive the internal voltage regulator failed. I did buy a new regulator an installed it into the original alternator. But I'll only know the outcome from doing that rework, if an when I have to replace it again. Not sure if all models incorporated that lighting bolt display, but it sure got your attention that you were in trouble.
By chance do you have the internal voltage regulator part number?



JAM
 

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The regulator I got uses a couple of P/N,s. A3TG4181 an A3TG4091 Also it pretty much says that this regulator is for use in the base an GT alternators only. Probably also fits the GXP version, but doesn't talk about it. I got mine from "rareelectrical.com" Looks like they are located in North Carolina (I thought it was Georgia when i bought mine. But whatever) It can also be had thru Amazon (sourced from *rareelectrical.com*) for about $36 at either source.
 

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Discussion Starter #7
The battery is only a couple of months old, so I assume it's probably ok. I ordered a replacement alternator from Amazon yesterday and should get it on Monday. Hopefully that fixes it right up since I couldn't find any bad connections anywhere.
 

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The battery is only a couple of months old, so I assume it's probably ok. I ordered a replacement alternator from Amazon yesterday and should get it on Monday. Hopefully that fixes it right up since I couldn't find any bad connections anywhere.
While waiting for the alternator to arrive, you might as well get the battery tested at your local auto parts store.
 

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The regulator I got uses a couple of P/N,s. A3TG4181 an A3TG4091 Also it pretty much says that this regulator is for use in the base an GT alternators only. Probably also fits the GXP version, but doesn't talk about it. I got mine from "rareelectrical.com" Looks like they are located in North Carolina (I thought it was Georgia when i bought mine. But whatever) It can also be had thru Amazon (sourced from *rareelectrical.com*) for about $36 at either source.
Thank you very much.


JAM
 

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Discussion Starter #10
While waiting for the alternator to arrive, you might as well get the battery tested at your local auto parts store.
Well I'll be...

I put my "intelligent" battery charger on the battery, and it exhibited the same intermittent charging issue and the charger gave the "check battery" warning. It seems like one of the cells drops out occasionally while charging. Found the receipt, so I'll be replacing that today. I'll hang onto the alternator for a week before returning it though, just to make sure it was indeed just the battery.
 

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By the way, what brand of battery are you using?
 

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i'm not a big fan of the autostores, but iirc it's still free to get your alt and battery tested. would be my first step. and didn't read the whole thread so sorry if i missed something.
 

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Discussion Starter #13
By the way, what brand of battery are you using?
I was using the Maxx EverStart batteries from Walmart, which have served me quite well in the past. I returned it yesterday, and the guy at the returns counter said he just had the same issue with one of their batteries in his truck. Maybe it was a bad production run or something. I have a new GM battery that I'll be putting in today, which should hopefully fix the issue.
 

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Not too long ago, had a less than favorable experience with a Wal-Mart Maxx EverStart H7 battery. It went haywire days after the free replacement warranty ended and with only periodic usage lasted a paltry +/- two years. Declined to pro-rate the battery and purchased a Napa agm (absorbent glass mat) battery to eliminate the possibility of acid leaking into the trunk. The original AcDelco battery was trouble free for almost eight years.
 

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Discussion Starter #15
So, quick update - I replaced the battery, but still got the alternator warning shortly after startup. I had a new alternator arrive today, so I installed it. Everything seems to be working well now. I guess the light was right.
 

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You solved 2 problems this time. The battery problem was corrected for a few additional $, but the Alternator (when that failure hits us), pretty much costs us all a couple of C notes. You've been building a small list of some normal as well as oddball problems this year.
 

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Discussion Starter #17
Yeah, it's like the car hit the 10 year mark and decided to rebel. Next is a ball joint that needs to be replaced...
 

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Yeah, it's like the car hit the 10 year mark and decided to rebel. Next is a ball joint that needs to be replaced...
I'm at 61k garage kept, non-wintered miles and still am worried about this 10 year mark i'm hitting this year. Sell now a little voice keeps whispering.
 
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