I have a 2019 Fleetwood Discovery LXE.  I called Battle Born to inquire about Lithium batteries.  Because I have a Firefly system I would have to get them to modify my system in order to get Lithium.  Has anyone run into this before?  And are there any Discovery LXE with Lithium?

Discovery LXE 40M 2021

I just replaced the house batteries with six 12v Battleborn 100 AH bank.  It turns out that the custom settings in the Firefly system doesn't keep the chassis batteries charged anymore supposedly because the bridge to the Magnum doesn't work right.  Not completely sure why not.  At any rate I have a email to magnum for support and also from Firefly.  I am trying to figure out where the connection between the magnum and the chassis batts occurs and who controls it.  

I can't find it in the wiring schematics from REV.  

Any help would be greatly appreciated.  

It is my understanding that the house batteries and the chassis battery are both charged from Shore power. I think it's done through the BBC or whatever you call that box that manages the charging of the house and the chassis battery.

Brett, you sir are an overachiever.   Battleborn makes a GC sized 100ah battery that fits the tray you had. The posts stick out the front instead of the battery top. It’s a perfect fit for where the old 6volt batteries used to be.   

I know it’s too late for you, but it will save others from having to repeat the welding experience.