2013 Lance 1172 compatibility with Lithium ion batteries

I REALLY APPRECIATE THE QUICK REPLIES. I found that the PD converter 4000 I have will NOT, HANDLE LITHIUM, LIPOF4, ETC batteries. Also, my solar charge controller may not handle either. So i am reluctant to put a lot of money in upgrading due to age of camper. I will likely go to 2 AGM Group 27 batteries, so if any suggestions on good ones of those let me know.
thanks again....will know now that there is more to it than meets the eye. I am glad I did not buy Lithium without checking.

Steve