Look inside your circuit breaker panel for a white lable. It will have your converter model number.
You can look up the specs and manuals for your model on PD website.
For example mine is a Progressive Dynamics PD4575K18LS8.
It is not lithium ready but there is a charge wizzard mode select button (next to the green flashing light). I can set it to boost mode and it puts out 14.6vdc for 4 hours then it reverts back to normal mode automatically.
I put in 4 lithium batteries and I kept the original (new) FLA battery as a back up. I installed a battery select switch so I can control which battery group is selected.
As said above, lithium batteries charge fast.
Just don't charge them at below freezing temperatures.
Here is an excellent article about it.
How to find happiness with lithium batteries
https://www.solacity.com/how-to-keep...tteries-happy/