Just got another bass boat a week ago, this is my second bass boat. I got it for a great deal. I'm confused to how it works. It looks like an on board charger, not sure how it works and why there all the wires are going to one single battery. My pro craft is newer and has a plug in right next to the passenger seat. That's why I'm confused. Hopefully this doesn't sound dumb! Any help would be appreciated. Black box is in pictures.