It's not based solely on 12v battery voltage. Some have reported the there is a "target SOC" of 80% and some hybrids have AGM batteries type specified so maybe that voltage would be the start voltage or the charge to voltage. I do see on my hybrid that it will charge higher maybe once a week, not necessarily during a longer drive. I do put a noco g5 maintainer on my 12v every 3-4 months for several days not continually for a week but as much time as possible for about 7 full days run time which might take 10-12 calendar days. If you check battery voltage after driving you need to do so an hour or so after turning truck off. Remember that opening the door or hood will turn some things on which appears to me to lower voltage readings as much as 0.1 to 0.3 depending on what gets turned on and where you take readings. In any case be sure to attach any ground connection temp or permanently after the bms on the negative post or the bms cannot see the current coming into or leaving the battery and become confused whether battery needs charged or not. Good luck.
When the vehicle is in use the 12v battery should be charging at a rate of around 14v depending on load. I don't remember where on the forum the information is, but it will start charging the battery when demand/load is high enough to warrant it, or if the state of charge gets into the lower 12v.
