2022 2500 drains trailer batteries

[wwest]

For the last two weeks while towing our travel trailer the two 100ah lithium batteries have gone dead. This first became apparent when we tried to boondock (1st time with truck and trailer) and the batteries dropped quickly. I have checked everything in the trailer and had a mechanic go through the electrical system...no issues with the trailer. I would disconnect the batteries while at a campground and charged them via the shore power until there were fully charged per a volt meter.
After traveling a few hours with the 7 pin connected the batteries are dead again!!!
Any thought on what might be the issue? I ordered a 7 pin tester that arrives tomorrow to see if the problem is in the connector. At a loss!!!

 

[crash68]

Sounds like you need to add a power idolator to the trailer 7pin wiring so the power can't flow back into the truck.
As it is now the 7pin +12V terminal is just connected to the battery with just a fuse inline, it stays hot all the time.