Here to help whenever I can, and thanks
Ok so you are right about the voltage being better with everything Off, and 12.1V with A/C blower and radio is understandable (not necessarily bad).
With a multimeter, check at the battery in the morning, or after an extended rest (8+ hours), to see where your resting voltage is at. 13.8V running at idle is also possible, with some draw from regular stuff like the blower, because at idle the alternator is not fully charging.
But I'm still worried with those running voltages you mentionned earlier (from EVIC/DID) at 13.7 - 13.9V.
About the basic warranty : sorry, my bad... it is 36K miles. I live in a metric system country and I do still (though rarely) mix up miles with kilometers. 36K miles is 60K kilometers...
How recent is the Trigger System ? The thing is, *if* a drain caused your original battery to fail early, it has to be something else... that was installed further back in time. Unless that battery just died because of a defect (we've seen that here on the forum).
Anyway, you could unplug it and let the HIDs be your guide.
If not that, maybe the winch ?
Is your multimeter capable of checking DC current (amps) ? If so, you could possibly check a few things yourself, like checking rest draw at the battery and then, if higher than normal, you unplug one accessory and re-check, etc... We can get you at rest current numbers if you can do this... Draw is current (amps), not voltage, so you need a meter capable of measuring current for this...
Also keep an eye on the running voltage (EVIC/DID) for the next few days. If you don't see 14V (or slightly higher) it would confirm (to me anyway) that there is a problem with the battery.
Buying a new battery is one way to rule out a failing battery, but... it's an expensive way if it turns out your actual battery isn't dying yet.
There is one brand of battery that appears to stand above all the rest, and it's Northstar. This is according to specs and online searching (various forums, etc...). The battery you have right now is built by Johnson Controls, and is sold under dozens of different labels/distributors (Exide, AC Delco, Diehard, Bosch, Duracell, Autocraft, the list goes on and on...), but the Northstars are not as *common*. You can buy them as Northstars, or from Batteries+Bulbs as X2 Power models.
Caveat : they are expensive...
Here's the group 94R : https://www.batteriesplus.com/produc...ls/sli94ragmdp
Northstar also makes one bigger battery that fits (just barely) in the KLs and it has 40% more reserve capacity. It's the group 27F X2 Power. Even more expensive, heh, taller and heavier. I'd recommend that only to those who really abuse their battery though...
One thing to do first : check your battery posts to make sure the connections are tight. I've read from others and noticed myself they are a strange design and not easy to get on tight, especially the Positive side. If loose, remove and clean underneath (top of battery, around the post), and when re-installing make sur you wiggle them fully down, or else they won't be tight enough.
I gotta go for the rest of the day. I'll be sure to monitor this thread when I get back, and regularly though.
Edit : I posted this before seeing your last message about the 5.1 mA. I'll need to do some searching on that... later. And this answers my above question about your ability to check current lol.