What does your volt meter say?

[stevek]

Oh ya, defiantly time to replace. Dead battery this morning.

That's what happened to me. I went to start it one day, it was a little sluggish. Next morning, nada.

 

[sumo]

Im surprised that i got this much out of a oem battery

 

[doubletapdrew]

They should be at 14.5v while running and around 12.5v when off.
When the factory battery in my 07 went toes up (think it was around 4 years old at the time) I replaced it with a 78dt6yr which is what we usually put in the duramax pickups. Our tech said the stock battery is awfully puny for all the electronics the denalis have so they don't last very long. I think my factory battery tested out to something like 35 amps on the load test, lol. Def. time for a replacement.

 

[imi4tth3w]

The alternator is just active and charging. When it's at a proper voltage it'll kick off and that's when you'll see it around the 12v mark

no. no. wrong. no. absolutely not.

when you car is on (engine on) it should ALWAYS be around 14-15v. only time it should go down is because of either lights, stereo, any electronic drain. if it goes down to 12, 13v under normal driving, something is wrong with your alternator.

there is only a few exceptions to that, as in my honda civic VX which has ELD (electronic load detector) that will disable my alternator for a little bit when there is no load being put on it and driving under 40 mph to save fuel. this savings is extremely minimal but this only apples to certain honda fuel saving vehicles. its every little bit that counts. which does not apply to any full size chevy. but otherwise, see above paragraph.

 

[Modded]

no. no. wrong. no. absolutely not.

when you car is on (engine on) it should ALWAYS be around 14-15v. only time it should go down is because of either lights, stereo, any electronic drain. if it goes down to 12, 13v under normal driving, something is wrong with your alternator.

there is only a few exceptions to that, as in my honda civic VX which has ELD (electronic load detector) that will disable my alternator for a little bit when there is no load being put on it and driving under 40 mph to save fuel. this savings is extremely minimal but this only apples to certain honda fuel saving vehicles. its every little bit that counts. which does not apply to any full size chevy. but otherwise, see above paragraph.

That is not true for the case of these NBS or NNBS GM cars.
They have regulated voltages and most of the time the voltage is under 13 volts unless there are a good amount of items in use (like the A/C or headlights). GM said it is done to save gas but I think it is the loads that cause it.
I know this because I have a system and Stinger volt meter installed and when the voltage goes down while driving I can switch on the headlights and it will go back up a bit.

 

[stevek]

no. no. wrong. no. absolutely not.

when you car is on (engine on) it should ALWAYS be around 14-15v. only time it should go down is because of either lights, stereo, any electronic drain. if it goes down to 12, 13v under normal driving, something is wrong with your alternator.

there is only a few exceptions to that, as in my honda civic VX which has ELD (electronic load detector) that will disable my alternator for a little bit when there is no load being put on it and driving under 40 mph to save fuel. this savings is extremely minimal but this only apples to certain honda fuel saving vehicles. its every little bit that counts. which does not apply to any full size chevy. but otherwise, see above paragraph.

If you were a little bit more educated, you would know that's not true with these trucks. PS - No need to call me out like that thinking I'm an idiot... it worked against you that time

That is not true for the case of these NBS or NNBS GM cars.
They have regulated voltages and most of the time the voltage is under 13 volts unless there are a good amount of items in use (like the A/C or headlights). GM said it is done to save gas but I think it is the loads that cause it.
I know this because I have a system and Stinger volt meter installed and when the voltage goes down while driving I can switch on the headlights and it will go back up a bit.

Yep^

 

[Vegasf6]

If you are seeing 14.5 to 15V your battery is excessively low. I think you have discovered this already though, huh? It either suggests a weak battery or some sort of parasitic drain in your system.
Also this constant charging at high currents (as that is WHY the charging voltage is so high) is tough on your alternator.