Question?

There can be a lot of reasons why converters do not charge. One of the most common is that the converter is putting out full power, but the positive or the negative heavy duty wires to the battery are not solidly connected. Before you abandon the converter, please check the power output right at the converter output terminals. My batteries went dead after 4 days of being plugged in, and had I paid attention to the idiot lights I would have caught it sooner. We arrived after driving, battery fully charged 3/4 lights on. Once I plug in I get 4/4 usually. Next day down to 2/4 then 1/4. Battery voltage way down. Converter output 13.6 on the terminals. I found the negative feed to the battery was loose in it's screw terminal.

When they remove your converter, they always tighten the terminals too. I often wonder how many converters have been changed out because of faulty wiring.