Ultra III converter installation

[Teton Stream]

Just finished the installation of Randy's suggested Ultra III replacement for the 55A Parallax 6300 converter. The information on this forum is terrific and answered 95% of my questions before and during installation. I have a 2013 20' Flying Cloud and have also swapped my flooded batteries for AGM's. Two questions that I could find no answers:

1. Upon disconnecting the old converter I had two black wires (soldered together as one) running into the A/C circuit breaker. One was the power for the converter the other was spliced to the pigtail via wire nut to a 12ga black wire leading out the back of the A/C box. As per Randy's instruction connected the converter power line and the "black 12ga" line together with wire nut and ran pigtail into circuit breaker. He could not answer me as to what the black 12ga wire was powering. Any ideas/thoughts?

2. Upon connecting battery box to system (AC power off) I noticed the Charge Wizard monitor LED lit up and was blinking (storage). I was under the impression the LED represented active mode of the charger. With AC power disconnected is it showing the computed charger stage (Boost, Normal,Storage) need for the batteries?

Installation did take longer than the advertised amount by a factor of 2.5, but I am not a professional in any way. Directions were very good. Everything went as well as could be expected. Next is the Trimetric battery monitor.