I am currently in the middle of all this. We had been on a 3-week trip a year ago and the battery was not charging. I purchased a lithium battery thinking it would solve the problem. This year, just got back from another 3-week trip and had a dead battery for the last leg. Contacted GD CS, had tech come out and the solar charger is faulty. They are sending a replacement. Also, during the evaluation, it was determined that the breaker/fuse box would not handle the lithium (even though the sticker on it said it would).....We will have to pull the breaker box out and send it in to have the firmware updated. They will repair and send it back to reinstall. This is all under warranty.
I have also ordered a dc-dc charger to go from the truck to the trailer.