Can you convert yes.
What's involved
First you will need the new batteries
Second likely a new converter.... LiFePO4 has a slightly higher charge voltage
Finally you may need an electronic box between the engine/house isolator and the house... Basically a current limited DC/DC converter Depending on the vehicle (not house) electrical system... I think (Key word THINK not sure) GM alternators will work well with LI. not so sure about Ford or Chrysler.
If you have two 12 volt batteries in parallel going to a pair of GC-2 Flooded wet 6 volt in series might also help.. But I think the LI option is better.
