Regarding the voltage shown on the meter

[5.0kit]

This morning, when I started the engine and was about to drive, I noticed that the voltage displayed on the meter was 11.8V.


As I picked up a bit of speed, it increased to 12.0V, and after driving a little further, it returned to the usual range of 12.5V to 13.5V.


I’ve never seen it show 11.8V before, so I’m worried it might be a sign that the alternator is starting to fail.


Has anyone else experienced something like this? If you know anything about it, I’d really appreciate your input.

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[ORRadtech]

Go by any chain auto parts store and have them check the battery and charging system.

11.8V would indicate to me a failing battery. Low charging voltage could be an under preforming charging system or simply one struggling to charge a bad battery.
The dash voltage guage should read 14.2V (+/- a couple of tenths) on a property functioning system.

So it's possible that you have a bad battery OR a poorly charging system OR an inaccurate meter OR some combination of the three.

The only way to find out is testing. Internet speculation Is just speculation...

 

[sk47]

Hello; I agree with ORRadtech , go to a one of the chain auto parts shops. They can do some checks.
You can do basic checks yourself with a volt/ohm meter. Check the battery with the car shut off for voltage. Then check at the battery with the car running. Car off it is desirable to have 12 volts or more. Running ought to give around 14 volts.
Modern cars suck power from a battery even when the car is shut off. But a good battery ought to hold 12 volts + for a time after a shut off.
Might check to be sure no power ports have stuff left plugged in. Some such ports may be live only with key on, but others stay live all the time. The extra draw over night may make a difference.

 

[Paul McWhiskey]

Hit the easy button first. Remove the battery, charge it on the bench after making certain that there is enough water in it to just cover the plates. Great time to clean battery box, battery and terminals. Once charged, reinstall and drive car as you normally do. If it still has symptoms have charging system checked and make necessary repairs.

 

[SheepDog]

This morning, when I started the engine and was about to drive, I noticed that the voltage displayed on the meter was 11.8V.


As I picked up a bit of speed, it increased to 12.0V, and after driving a little further, it returned to the usual range of 12.5V to 13.5V.


I’ve never seen it show 11.8V before, so I’m worried it might be a sign that the alternator is starting to fail.


Has anyone else experienced something like this? If you know anything about it, I’d really appreciate your input.

Disconnect the BMS sensor, this will force the Alternator into full output. This will tell you if the Alternator is indeed charging, or if it is just the BMS system doing it's nonsense

 

[SheepDog]

making certain that there is enough water in it to just cover the plates

I could be wrong, but it's been a good 40 years since the last time an auto manufacturer installed a serviceable battery from the factory.

 

[Farkel]

I could be wrong, but it's been a good 40 years since the last time an auto manufacturer installed a serviceable battery from the factory.

I don't know about your '22, but my '20 came with a good ol' flooded battery. If yours has removeable caps, it's "serviceable".

 

[5.0kit]

Thank you, everyone.


Sorry for the late reply.


Let me explain the situation in more detail.


The battery is an AC Delco, and I just replaced it six months ago. Of course, I also reset the BMS.


At the time when the voltage was 11.8V, the air conditioner was on — it’s been pretty hot lately.


Also, I started the engine with the key before getting into the car.


Since the air conditioner uses electricity, I wonder if that had something to do with it.


Do you guys think the air conditioner might be related to the low voltage?

 

[5.0kit]

Disconnect the BMS sensor, this will force the Alternator into full output. This will tell you if the Alternator is indeed charging, or if it is just the BMS system doing it's nonsense

I’m interested in this.


Is it safe to start the engine with this connector unplugged?


If it works, the voltage on the dashboard should show the alternator’s full output, right?

 

[5.0kit]

Today, the gauge was showing a normal 14.2V.


Though I didn’t have the air conditioner on.


Maybe it just wasn’t working properly yesterday?

 

[jloshotz]

Also, check voltages at the battery with a quality digital multimeter to confirm. My entire chaging system is about two months old, (‘16 GT) and let me tell you……the dash display will drive you completely batshit crazy. Mine still does the same thing you are describing, after replacing the alternator pigtail, alternator kit (w/belts and pulleys) and a die hard gold battery. And the car is 100% fine. It’s the “service charging system” warning that is the biggest indicator of an issue. If you aren’t seeing that, just keep an eye on it. THAT is what prompted my changing of said parts. With that indicator lit, you know there is an issue VERY quickly. Mine at first would come and go, then one day, it just stayed on, and the centerstack said something to the effect of “shutting down uneeded electronics to conserve power” and then whole centerstack shut down. Time to get it parked pronto. If your charging system is toast, your car has no problem letting you know about it, believe that. 🫡

 

[glockholiday]

These cars also have a "smart charging system". It's not like an old school alternator where at idle it might put out 30 amps then over 1500rpm it'll put out 130 amps. I've seen anywhere from 11s to 15 volts on my 19' it's supposedly to make the battery last longer not just always pumping amps into it to be at peak voltage all the time.

 

[Paul McWhiskey]

I could be wrong, but it's been a good 40 years since the last time an auto manufacturer installed a serviceable battery from the factory.

My ‘17 came with a lead acid battery that was serviceable. It was replaced with the same.

 

[sk47]

My ‘17 came with a lead acid battery that was serviceable. It was replaced with the same.

Hello; I have been able to open the cell lids on batteries in the last years. Not as simple as the old screw caps but doable. i check fluid levels and sometimes add distilled water.

 

[Rebmo]

Some caps are under labels.

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