'07 Sub "Service Battery Charging System"

This may be an amateurish question, but here goes anyhow....

After a trip my Sub sat out overnight and the next day it flat wouldn't start. Thought maybe I ran down the battery somehow, got a jump, and drove the trip back no prob. Sub sat for 2 days, then my wife took it around town. Was slow starting on her last stop but made it home. Very next day we go to take it and again it's too dead to start. Jump it and now I get the warning message listed in my title. Drive it like this and the voltmeter is showing 14-15V so it's not anything but the battery that I can tell. Also, the rig started just fine after sitting in the cold all that night and the message went away.

My question is, is there anything other than the alternator that can affect how the battery is charged? This rig has so many FREDs that I'm worried there might be. I assume it's the battery with a bad cell, but you can't buy aftermarket yet and I assume the dealer will nail me for $200+ for one.

Most alt charging is computer controled on newer trucks .
Check battery cables and cabel ends and grounds.
Most battery places can test battery and charging system.
Have the battery load tested and voltage check and check system for amp draw key off.
What is the problem with getting aftermarket battery?

Thanks for the reply. The aftermarket batteries don't have a direct replacement listed for this model. There's some funky unnecessary plastic shroud over the + terminal shaped to fit that battery. I could probably make another one work, but... I will have the battery tested.

Keep checking with your battery places.
They should have a direct fit battery for it or be getting them in.
O'Reilly auto parts show one for 07 and 08.
Good Luck

I had a similar problem with my '07 Suburban LTZ. After realizing that GM really went cheap by installing a 600-650 CC AMP Battery in a vehicle with so many options, I shopped around and found a 750-800 CC AMP battery that is exactly the same size as the factory. I bought it at Wal Mart of all places for $85. Two Ohio Winters later and everthing is O.K.. You can also install a second battery (The tray is already in your vehicle). You can buy a dual battery wire kit at the dealer or aftermarket or make your own. I'm a GM employee. So I hate admitting that GM purposely cuts corners. But, this is definately one of those occasions. With all the bells and whistles in our vehicles, you can't expect a battery that is even slightly weak to last very long. Good Luck.

The battery was really weak. Showed good voltage, but when I put a load tester on it it took no time to kill it.
Reddog, how much did the dual wire kit run? I wonder if there aren't any aftermarket kits since I'm pretty sure the dealer will gouge me.

I don't recall the prices exactly, but I think around $50 for aftermarket and a around $100+dealer. Shop around online.