Stone Cold Who Done It

What's the easiest way to check for phantom loads on my 12V?

All, I have a 2009 with the key fob. Recently (about a month ago) I replaced the 12V battery (got the ABS brake system warning, was connected to low battery voltage). Twice now, my car has failed to start and I have had to jump it. Now the stone-cold who-done-it part: I have a GPS tracker plugged into the ODS port. The first time the car wouldn't start, I noticed the port wasn't getting any power and the fuse for it was blown. I figured that was the cause of the drain, but since the fuse was blown, should not happen again. I charged up the battery overnight with a trickle charger, and bam happened again a couple of days later, in cold weather. The inverter is putting out 14V, so I have narrowed it down to two options: 1) The 12V battery I got was bad or not the right size? 2) There is some fantom load draining the 12V.

I know it's probably the first one, but how do I check for phantom loads? Was the ODB fuse blowing just a coincidence, or is it signs of bigger problems?

Thank y'all!

 

Thank you so much. I would not have thought to move the key fobs away, or let it sit for an hour! Any suggestions of likely culprits?

Thank you again!
Tristan