General Maintenance & Repairs - 12.5-12.9 volt reading?

Is that kinda low? Ac is running at this reading , just alittle higher with it off

Yes that's low. Your reading this at idle right?

Where are you getting this reading from? If you're reading ignition voltage with a scanner via the PCM, it's going to be lower than what you'd see at the battery with a multi-meter. With the load of the A/C compressor, high speed cooling fans and the blower motor, all running at idle (especially if it's an A4 with it's lower idle speed), depending on where that reading is coming from it may or may not concern me.

This is 6spd, the gauge on cluster, I can see a gap between red needle and white line for 13 at idle with ac on max, longer I sit looks like it slowly creeps down

My idles sitting at around 825-850rpm if it matters, and high 80s low 90s temp outside

i see a truck alt in your future !!!

yeah your gonna need a new alt soon, when you put it under a load like putting the lights on or kicking on a/c it should jump from like 13.5 to 14 volts

i see a truck alt in your future !!!

If the truck alternator was required for adequate charging with a stock electrical load, stock wiring and good ground contacts, then none of these cars would have ever charged properly from the moment they came off the assembly line.

All the pimping of truck alternators, as the cure for all charging system issues with stock electrical loads, leads me to believe that my four LS1 F-bodies must've been the only ones in history to leave the factory with working charging systems in stock form.

my gauge must be off because when hot at idle it right at the red line , but if i check the battery with my meter 13.5 on the dot, and the car has white face gauges . Is 13.5 good at idle when hot with stuff running. ?

i am sick and tired of the truck alt putting out 14v at idle....with the a/c full blast.........lights on.....stereo full volume........back the stocker goes on so it can be in the red during those times :)

All the pimping of truck alternators, as the cure for all charging system issues with stock electrical loads, leads me to believe that my four LS1 F-bodies must've been the only ones in history to leave the factory with working charging systems in stock form.

I once heard that pimpin ain't easy... https://encrypted-tbn2.google.com/images?q=tbn:ANd9GcRGWQvww2u9eQ8UBV4o8ewEqWnlCXz7i Z0G4V8dvabqqEWvxesd

I'd also add that GM would have recalled these cars if the stock charging system was deficient.


For the OP - you are normal! 13.2 Volts is the theoretical perfect battery voltage. As long as you don't drop below 12 with the headlights on and the A/C on, all is well.

The red lines are on the gauge for a reason. As long as you aren't close to them and are using the car for stock purposes, you are fine.

i am sick and tired of the truck alt putting out 14v at idle....with the a/c full blast.........lights on.....stereo full volume........back the stocker goes on so it can be in the red during those times :)

Ha, I really miss the pulsating lights at idle as well. Upgrade to a used truck alternator and never look back!

I once heard that pimpin ain't easy... https://encrypted-tbn2.google.com/images?q=tbn:ANd9GcRGWQvww2u9eQ8UBV4o8ewEqWnlCXz7i Z0G4V8dvabqqEWvxesd

I'd also add that GM would have recalled these cars if the stock charging system was deficient.


For the OP - you are normal! 13.2 Volts is the theoretical perfect battery voltage. As long as you don't drop below 12 with the headlights on and the A/C on, all is well.

The red lines are on the gauge for a reason. As long as you aren't close to them and are using the car for stock purposes, you are fine.

:nod: Agreed.

i am sick and tired of the truck alt putting out 14v at idle....with the a/c full blast.........lights on.....stereo full volume........back the stocker goes on so it can be in the red during those times :)

That's great, except that 14 volts at idle with a full eletrical load is not necessary for proper operation. ;) If your stock unit was in the red zone with the lights/AC/radio on, then it was failing or you had wiring/resistance issues that were less than ideal. A properly functioning stock system can handle this load without dropping into the red.

Ha, I really miss the pulsating lights at idle as well. Upgrade to a used truck alternator and never look back!

No pulsing lights here either. Except that I'm still using an LS1 alternator....on both of mine....without any pulsing or red zone issues. It must be magic! :jest:

...same issue here folks... My 02 WS6 battery is draining....Had the alt tested with the car on idle and it read 12.92.... I drove it home(5minutes) and my check gauges light came on and I noticed the batter running low again?.... so Do I need to get under my car and replace the Alternator?