Thanks Everyone. We are on the road, I should have some time in the next few days to post the make and model. It is hidden under a cabinet and I need to pull drawers to get to it.
I don't have a multi-meter with me, but we are heading home next week and I have all of the equipment there. Everything seems to be working correctly, the batteries are not boiling, but we have a loud buzzing from the converter.
We are in southern California right now and while the days have been warm the furnaces run at night so some of the charging is to replace the draw from the batteries.