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Battery Light ON

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Old Jan 18, 2022 | 8:33 AM
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RickR90s's Avatar
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Default Battery Light ON

My truck is actually a 2007 Silverado Classic so I thought it would be better to post here, since it more resembles the earlier series.

I'm the original owner with 165,000 miles. 5.3L V8, and I believe it has the higher output alternator, but don't remember how to check.

Nearly everything on the motor is original but yesterday, the battery light stayed on after starting. The dash voltmeter was registering about 15vdc, so I checked at the battery terminals with my Fluke meter and it was around 14.8vdc at idle. My first thought is maybe the voltage regulator is suspect.

I decided to drive my other car and check it when I got home.

So I started it again, and this time all was normal, with the battery light now OFF. Voltage at the battery was a little lower, about 14.6vdc at idle.

The voltage appears to be normal but will the battery light come on IF the voltage exceeded an upper limit?

btw, Battery connections are clean and tight, as well as last year removing the engine ground cable and cleaning.


Thanks,

Rick
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Old Jan 18, 2022 | 2:15 PM
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From: kevinkpk
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Originally Posted by RickR90s
My truck is actually a 2007 Silverado Classic so I thought it would be better to post here, since it more resembles the earlier series.

I'm the original owner with 165,000 miles. 5.3L V8, and I believe it has the higher output alternator, but don't remember how to check.

Nearly everything on the motor is original but yesterday, the battery light stayed on after starting. The dash voltmeter was registering about 15vdc, so I checked at the battery terminals with my Fluke meter and it was around 14.8vdc at idle. My first thought is maybe the voltage regulator is suspect.

I decided to drive my other car and check it when I got home.

So I started it again, and this time all was normal, with the battery light now OFF. Voltage at the battery was a little lower, about 14.6vdc at idle.

The voltage appears to be normal but will the battery light come on IF the voltage exceeded an upper limit?

btw, Battery connections are clean and tight, as well as last year removing the engine ground cable and cleaning.


Thanks,

Rick
The voltage regulator is internal to the alternator. If you have an over voltage condition such as you posted, I'd look at replacing the alternator. High charge rates as 14.8+ will fry a battery.
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Old Feb 2, 2022 | 8:08 AM
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From: Detroit
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a quick update:
I pulled the alternator (DR44G) and took it to my local rebuild shop here in Jackson, MI.(Sure Start Auto)

Great guys. They tested it and said it's perfectly fine. Outputs about 14.6vdc at various RPM's. I also got a tutorial on the Battery Current Sensor system, which apparently has a few algorithms based on battery temperature, charge level, etc.

So I re-installed the alternator, cleaned all the contacts (they were already clean and had dielectric on them) and cleaned the BCS connector as well.

FWIW, battery voltage seems normal, with about 14.6vdc showing on startup with Rear defrost and lights on.

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