that nut is back out too much, tighten it back down a couple turns, it should come loose, unless you buggered it. My 14 sport has sat for a few days with no problem, Wifes Honda will drain down in winter in a week if it is not ran. I have checked for current draw with meters and it is in spec. Battery is fairly new, door not fully latch will kill it over night.
That will not happen with these trucks as the computer will turn off the interior lights
My truck battery is still the original battery, but these only 80K on it
They do live in the garage, so that makes a difference, it stays about 0-+5C at average winter temp, when we where -35 or so for a few days it was -5 to -8 c, not a big deal here.
Battery maintainer is just a small battery charger, trickle charge ,about 2-3amp that usually is mounted by the battery , hard wired in or clips, and you just plug in at night, keeps the battery toped up.
There was a discussion a week or 2-3 about this here.
Finding a current draw is a pita, but with a good meter, or even a cheap one ,it.
can be done.
You kind have to know what to look for and what current draw should be
There will always be a little draw.