So if you disconnect the battery for the day, it will start the vehicle OK after you hook it back up ? When you started at 12.2 volts that's less than a 50% charge. Did you have the battery checked under load?
If it's OK, then take the + cable off the battery, put a test light between the post and the cable and start pulling fuses. BTW, you were using a voltmeter not an ammeter. If it's drawing that much power you probably shouldn't hook up a multimeter in ammeter mode.
I'd start with unhooking the the red wire at the alternator. If you have a diode or 2 burned out power can run through it. Does it charge ok? Another big draw item that you might not notice is on is the rear de-fogger.