Replacing my wet cell batteries for lithium

[LenS]

The Green TARDIS is now 21 years old. I want to replace it with a commercially built RV but the one we want has A 1.5-2 YEAR back order!! So we keep our B for two more years. I am in the process of replacing the two 1.5 year old 6v golf car batteries with two 100a 12 volt Renogy lithium batteries. Also changing out he solar panel controller the Renogy 30a DC On-Board Charger w MPPT. Taking awhile since I am also cleaning up the electrical wiring. The van "evolved" over its 21 years with electrical changes and I want to get rid of the patchwork. I figure that when I sell the TARDIS if two years I will re-install the golf car batteries and put the lithium into the new rig which will be a B+. We are seriously $$$ looking at the Leisure Travel Van Wonder with a rear lounge. Not as tailored to our camping style as the TARDIS but I have no interest in building another one.