The voltage will drop when idling, but you gave us no readings.

 

Finally able to get back to the car. I was able to get a charger, get the vehicle started and no lights etc, it tested out at about 13.73v after I got it moved to the driveway to work on. I just checked the battery it was at 11.73v, and that's after sitting for about a week. It started right up, no errors, or lights. While it was running it was about 14.2V and slightly dropping down, got to about 14.12v ater a few minutes and I turned it off. go back to check the battery it's about 12.2v and dropping it got to about 12.05v before it slowed down. It's been 10min and now the battery looks to be settled at 11.77v.
So did I get a bad battery? It was a brand new Duralast AGM, exactly matching my previous one that lasted 4 years.
Any other readings I can get ya?

 

Keep in mind when idling, voltage may be nominal but actual amperage is low. Need to operate it longer, as in drive it, to see if the battery will charge up. A standing battery, with no load, should hold over 12 volts. 12.2-12.6 is good. But your running voltages seem good. Over 14 is typical, especially if cold outside. Once truck is warmed up, then its lower. 13.2 should be towards the bottom end of a typical alternator output when driving and things have settled. With that said, at first glance it seems like a bad battery or you have some sorta severe power drain. So drive it for a while, like 20 minutes, and then see how the battery behaves. If it seems to drain fast, drive it again. Then disconnect the battery and see what happens. If voltage does not drop as much disconnected, you likely have a power drain. Keep in mind the battery voltage will drop a lot after driving as it settles (about 10 minute) but it should stay above 12v. My aux battery settles at about 12.6 volts - used for camping, so I am always seeing its reading.

 

Thanks @DakotaTravler , I'll try that and record what happens

 

Update readings so for a few days in a row seems to settle at about 11.87 after sitting. So far starts right up, no lights or warnings

11.88 before starting
14.2 while first running
13.7 when i parked (20 min runtime)
12.8 when I turned off the car
12.2 about 10-15 min later
12.02 about 20 min after
12 about 30 after
11.87 this morning after sitting all night

: UPDATE - Took it out for a couple errands, was 11.87v before leaving, started up about 15 min later, radio, map screen, climate control, the whole center console electronics went out, dash reset (cleared then partially came back), TPMS error and low error light, nothing came back on. I was able to get home, battery checks in at 12.2V with it turned off. negative is tight at the battery, checked it again last night and today, it's not moving.

Forgot to add it now won't start, TPMS error is back and battery is reading 12.35v (starting to question my meter)

@DakotaTravler

 

Do you have a navigation display?

Starting to think bad alternator, or maybe both (not unheard of). Need to know full operating voltages when running. But now it won't start even with over 12v?

 

Have you gone back to AutoZone to have this new battery load tested?
I could be a dud.

Just last week I got a "parking brake error" and erratic voltage on my 3.5yr old AGM.
Charged back up to 12.45v - sluggish start, 14v while running.
Charged back up to 12.45v - wife got stranded, jumped fine to get home.
Charged back to 12.45 - no start, down to 9.5v. - battery couldn't hold anything.

New one fixed all my problems - as usual.
Got a Walmart AGM H8 with a 4yr free replacement - maybe it will also die at 3.5yr and I get 7+ yrs on this purchase.

LR3s hate low voltage like no other.

 

I did check the new battery again and it was fine. I finally got a new alternator and installed it. easy swap, hardest thing to do was get the jacked up, it was bottomed out and factory jacked is messed up, but finally got raised enough to use the bottle jack I got. Anyway, after getting installed had to go through the hard reset process and it took longer than expected, about 10 min having + and - connected, then I left the cables off for about 2 hours. Started up, all errors gone. took it around the block all good. turned it off, and turned it back on, U0167 was back, was able to plug in cheap scan tool clear it and it's been fine since. It seems to be running strong, but I all my errors, from suspension, to e-brake issue, to HDC, TPMS, etc, all cleared. now, to get to get the front lower control arms replaced...always and adventure, but it beats a car payment.

 

Interesting and very much appreciate the update.

 

ok gremlins came back after 24 hours, going to try the hard reset again, saw something say to wait 15 min to connect the neg / positive, so trying that