This RV is "new to me" and I thought I had a GEL battery for the chassis. Turns out it is a Red Top Optima that is a AGM battery and not a GEL. Not sure if this plays a part in my mystery.
I am starting to read up on these batteries and learning that they may not perform well after experiencing a deeper discharge. All my challenges started due to the RV being in storage and after about 3 weeks finding out I needed a boost to start. That lead me to getting a battery disconnect installed and then shortly after finding out I had a bad cell.