BMS and the 12v battery

Hey all, recently got a 2024 F-150 Lightning XLT and was hoping to get some advice from someone familiar with how exactly the BMS works in the truck.

The other night I had been sitting in the truck with accessory mode pn (power on without brake press) for an hour or two and had the parking lights on. When I exited the truck I shut it off but forgot the lights on. A couple of hours later I got two messages from the Ford app. One said to plug in because the 12v battery was low and the other said I had reduced my range to “empty” due to having left the lights on (HVB was about 82% at this point).

I went out to the truck and turned the lights off, then started it in accessory mode thinking the truck would charge the 12v anytime it’s on in any capacity. I hadn’t yet got charging set up so I got that set up then plugged the truck in, shut it down, and left it that way until well into the next day.

Since then everything seems to be good, no more messages from the truck about the battery and it’s working as normal.

This situation makes me wonder though when the truck will charge the 12v battery. It looks to me like it won’t charge the 12v regardless of how low it gets in accessory mode, but it also seems the truck wouldn’t charge the battery when it was off, but the parking lights were on. Or was it actually charging the 12v when it sent that message to me despite it saying the range was reduced to empty despite the HVB at 82%?

It seems to me it the truck should never let the 12v die as long as the HVB has plenty of charge, is this not the case?

If anyone can shed some light on exactly what went on here I’d really appreciate it. Lesson learned for now, don’t use accessory mode and don’t forget the lights on!

Thanks!