12.4 or lower is a dead battery. I’ve had two occasions to experience this, once on vacation and once just two weeks after buying my 2011.
unfortunately the alternator can’t provide enough current to recharge a battery in this condition, it has enough work to do running the computers and lights, the radio and a few other things we take for granted.

 

Don, there wasn't a fire. Just extremely heavy smoke from trans fluid blowing all over the exhaust.

 

Update on this for you guys helping......yesterday I installed new O2 sensor #2. I was getting 12.3 volts at battery with car not running. Based on your input, I took it to Autozone where I had purchased it 6 months ago. They tested it and deemed it a good battery, but I insisted that my forum advice and research told me that my problems were either battery or alternator related and that it was no skin off their back to give me a fresh battery. The manager intervened and handed me a new battery off the shelf. To my surprise, ALL THE PREVIOUSLY ILLUMINATED DASH WARNINGS DISAPPEARED WITH THE NEW BATTERY INSTALLED.
Most notable for me was the tpms light, a "service airbag" light and message, and abs warning light. I have been driving this car for at least 2 years with the tpms and abs lights on.
Took the car for a couple freeway test drives and so far all is well. Smooth idling and no codes.
So I'm still perplexed but happy if this ends up being resolved. I need some more engine time to confirm. But wow!. Kinda weird that the car was functioning well enough to start and commute with the incidental warning lights on. Especially the TPMS. I had just determined that one or more of the TPMS sensors was bad and not effecting driveability, I just drove it. For two years. Now a fresh battery turns it off? It didn't have this effect when I installed the battery 6 months ago. Perhaps the battery I bought 6 months ago was just defective enough to start the car but not support the electronics?
Anyway, thanks to you guys who hung in there with me on this and gave me great instruction. I really appreciate you all.

 

Pulling the battery reset the computer. If you are lucky they will stay off.

What somebody called "IT mode"; unplug the computer then plug it back in, suddenly it is magically fixed.

 

understood, but as I said I have disconnected and even replaced the battery as recently as 6 months ago.and the tpms and abs liights never went away until yesterday. Hoping for the best. And Don....you always are helpful. Thank you.

 

Happy it’s running like new and that manager, helped you resolve the issues. Now , enjoy the drive! Give us an update in a month or so.

 

A bad battery can cause the alternator to go bad. You should have them test the charging system(it's free).

 

I accept that. Alternator is my next move if recurs. I'm seeing 14.5-15 volts on multimeter at battery, on the obd and at cm with car running. I'm hoping the alternator is healthy and charging but if the symptoms return after a few drives, I will assume that the alternator is not keeping the battery as hot as it needs to be..

 

The only connection between the TPMS and the ABS lights would be if one tire was so much different PSI that it caused the wheel speed to be different to the rest of the wheels. I am assuming that you actually checked the tire pressures with a gauge?

 

If the battery voltage is low, the TPMS won’t read the tire pressure sensors correctly and send signals from the RCDLR module to the BCM .
That new battery cured that issue, the BlackSwan suffered that issue a week or two after I bought it.