I have heard and even seen on another brand we looked at. I believe the functionality is to give either your Chasis batteries or your Coach Batteries the ability to share power. Not sure which battery is used to start the genny but in theory, it would pull from the other battery if used...and vice versa if the engine battery is too low to start, it will pull from the coach batteries...
Hope that helps clarify what appears to not be present on my rig.
2016 Forest River Georgetown XL 350TS
Ford V-10 (5-Star Tuned)