I also have a 2014 and indeed the converter has a 3-stage battery charger built in. It should have a small green led indicator located in the lower part of the breakers/fuses area, visible through a small opening, that tells you what the charger is "doing" for the batteries at any specific time. Next to the led is also a small push button that can be used to toggle the charger through the various charge modes. The functioning of the modes is automatic, the button is just there to "force" a mode change for diagnostic purposes.
I tried to attach the converter's owner's manual, but it is just a little too large to attach to a forum response. I will check and see if it is in the "Manuals" section, if not I will try to upload it and send a reply that it is there.
2014 Seneca 37TS
Toads: 2014 Ford Explorer Sport or 2013 Ford Focus ST