[robbie52]

What is your voltage reading after car has been sitting for at least 24 hours? My battery currently reads about 12.4 volts after sitting overnight without a battery trender on it. Never had an issue with cranking and I verified that the charging system is working properly.

[BlueinTN]

Where you reading it from?


Mines sat a few weeks I can check.

[cellsafemode]

is the assumption here that 12.4 volts in a 12volt battery system is not good after 24 hours and warrants concern?

or are we just taking a count of everyone's battery voltage for some other reason?

You should be concerned when your battery starts reading 11 volts or lower at normal 60+ degrees F temps, as that is a sign that it either isn't getting charged enough between uses or it can't hold the charge anymore.

colder temps will lower the voltage read. In freezing temps, reading over 9 volts should still crank over.


14 volts is the general charging voltage of lead acid 12v batteries and will only read at this voltage for a short time once charging has stopped as the surface charge dissipates. It will then settle at it's full charge voltage in the 12v range.

[avalonandl]

12.4 is fine. It should read 12.7 but 0.3 volts difference is not enough to worry about.

[craigss50]

Is this the original battery? If so maybe time for a new one.

[BlueinTN]

This is at rest with the key in my pocket. I think the cars sat more than 2 weeks.



Heres the amp draw.

[17rsvert]

Originally Posted by cellsafemode

is the assumption here that 12.4 volts in a 12volt battery system is not good after 24 hours and warrants concern?

or are we just taking a count of everyone's battery voltage for some other reason?

You should be concerned when your battery starts reading 11 volts or lower at normal 60+ degrees F temps, as that is a sign that it either isn't getting charged enough between uses or it can't hold the charge anymore.

colder temps will lower the voltage read. In freezing temps, reading over 9 volts should still crank over.


14 volts is the general charging voltage of lead acid 12v batteries and will only read at this voltage for a short time once charging has stopped as the surface charge dissipates. It will then settle at it's full charge voltage in the 12v range.

You should be VERY concerned if your battery reads 11 volts, that's pretty much a shot battery or a faulty charging system in the car. Under normal conditions, if the car has been running recently, after sitting for 24 hours a reading under 12.0 volts is an indication of a major problem. A fully charged battery should read between 12.6 and 12.7 volts. Even a reading of 12.2 volts is considered roughly 50% discharged.

[Jeb114]

You have an intelligent charging system on these cars the computer adjusts the alternator voltage as needed. Same with interior voltage. When the engine is running, the ECM sends an alternator turn on signal to the alternator. The alternator's internal regulator controls the current to the rotor by pulsing the current to obtain the correct output. If the voltage regulator detects a problem, it notifies the ECM by grounding the field current line.

I believe this went into Chevy's 2015

[robbie52]

I am reading the voltage at the fuse box under the hood with a volt meter. I am concerned because normally a 12V battery reads 12.8V when fully charged and in good condition. The battery is three years old, but I have never checked the voltage before and do not have any issues with cranking. Just concerned.

[Memphis SS]

Originally Posted by Jeb114

You have an intelligent charging system on these cars the computer adjusts the alternator voltage as needed. Same with interior voltage. When the engine is running, the ECM sends an alternator turn on signal to the alternator. The alternator's internal regulator controls the current to the rotor by pulsing the current to obtain the correct output. If the voltage regulator detects a problem, it notifies the ECM by grounding the field current line.

I believe this went into Chevy's 2015

I agree..

[BlueinTN]

after running the car about 10 mins and letting sit about an hour I got 12.64 VDC.

Couple of the charge pictures. This is the car running at idle.

[MiamiBlueCamaro]

Originally Posted by robbie52

I am reading the voltage at the fuse box under the hood with a volt meter. I am concerned because normally a 12V battery reads 12.8V when fully charged and in good condition. The battery is three years old, but I have never checked the voltage before and do not have any issues with cranking. Just concerned.

Follow this chart and be happy!

[ctrlz]

Originally Posted by robbie52

I am concerned because normally a 12V battery reads 12.8V when fully charged and in good condition. The battery is three years old...

12.4 V is on the low side in my book. I would check the voltage on this battery monthly. I have gotten up to 7 years with a factory battery on GM cars, but I average 5 years across all brands. I don't think your battery will make it to 5 years.

BlueinTN, I would be worried with 12.2 V after sitting for 2 weeks.

[BlueinTN]

No its not really good. I know for a fact the battery was stone dead at the dealership because I went to test drive it it was dead in the show room and they couldnt figure out how to charge or where and I kinda pretended to be mad and left...laughing all the way home. Not sure how many time that happened before I bought it.



Im just going to keep an eye on it this winter maybe a little better than I usually do.


I have had 3 Optima yellow tops go ten years. 2nd one I just gave up on last week. #3 I got to charge up finally with a fork truck charger at work and have been watching it all month.