Anyone running OBD2 solar battery maintainer/charging setup?

Wondering is anyone has any longterm experience running a solar battery maintainer like VW used to have for their cars shipped from Germany in their 3rd gen? Searched and didnt find any posts about it.

Its basically a low wattage solar panel that is plugged into the OBD2 port to maintain the battery.

 

I use a solar charger during the winter (my truck is not my daily driver). I connect mine to the battery plus and vehicle ground though. I ran a line to a SAE power socket mounted to my grill and plug the solar panel into it and set the panel on the windshield.

 

this truck sits and maybe gets driven once a week so having everything on the interior is my preference. Wish the 12v outlet would be always hot.