wacky alternator?

[redcoats1976]

i have a 2015 RS with 82,000 miles on it.lately voltage reads anywhere from 12.6 to 13.8.battery was tested,found to be low on CCA and replaced a couple of weeks ago.today i was driving down the interstate at 75,voltage 12.5 but when i got off the highway sitting at a light voltage went to 13.7.is this normal or should i be thinking new alternator soon?

[Aqua Blue RS/SS]

Both of my cars have charged all over the place with seemingly no rhyme or reason why. I think most of GM’s stuff from the last 15 or more years is the same way.

[gtstorey]

The computer controls the voltage output from the alternator and it changes constantly to "suit the conditions" and this seems to encompass a lot of variables.

[1JEWLDSSRS]

I have the Aeroforce dual gauges in my Camaro, and one of the things I monitor all the time is battery voltage, since the "stock" console gauges only have lines, and the other way is to check the DIC for what it reads. On a full battery my gauge sweeps back and forth between 14.9 and 14.3 when I'm driving, with or without the AC on. Sometimes while driving it will go down as low as 13.8 to 13.4 but then after a while, or after I stop somewhere for a bit then start her back up it goes back up to the 14.7-9 and just sweeps back and forth around there. This is all normal. I read on this forum somewhere that the numbers we are seeing is in fact what the alternator is putting out to the system, not the battery. As things change in the electrical system while to car is running, the alternator "adjusts" the voltage as needed. If you suspect the alternator is acting up, go get it checked to be sure. Hope this sheds some light for you.

[gtstorey]

Battery Voltage should really always be about 12.6. Everything above this is alternator output, below is battery getting weaker with no alternator voltage.

[redcoats1976]

so as long as it stays above 12.5 on the DIC im good?

[1JEWLDSSRS]

Originally Posted by gtstorey

Battery Voltage should really always be about 12.6. Everything above this is alternator output, below is battery getting weaker with no alternator voltage.

Yes sir! And this is how I knew when my alt went out.

[gtstorey]

Originally Posted by redcoats1976

so as long as it stays above 12.5 on the DIC im good?

I would be concerned if it got below 12.5, and I wouldn't expect to sit there very long before it goes back up. I'll try and check the service manual tonight and see if it gives an exact voltage range it should be in.

[1JEWLDSSRS]

See post number 12..

https://www.camaro5.com/forums/showthread.php?t=76484

[1JEWLDSSRS]

Originally Posted by gtstorey

I would be concerned if it got below 12.5, and I wouldn't expect to sit there very long before it goes back up. I'll try and check the service manual tonight and see if it gives an exact voltage range it should be in.

Helped ya out there gt..

[1JEWLDSSRS]

Found this as well. Post number 7..

https://www.camaro5.com/forums/showthread.php?t=245282

[gtstorey]

Originally Posted by 1JEWLDSSRS

Found this as well. Post number 7..

https://www.camaro5.com/forums/showthread.php?t=245282

So 12.5v is likely ok, but any less is likely too low. If it's reading 12.5 or lower, add some electric load and it should go back up.

[chevy pilot]

12.7-15.4V is normal.

[PaulsSS]

Personally at this mileage I'd be changing the one way clutch on the alt. Mine went out around 75k just driving along all of a sudden warning low battery voltage. Just barely got it home pulled the alt and found the clutch was toast. The system will not warn you that the alt is not charging but it will flash a low voltage warning just before the car dies.