OK - this is the first boat I have had with 120 an 12v power systems. I am looking at adding a TV and have found one that runs off a 12v 5 amp power supply. Here us the newbie question: If I put this on the boat, will it run off the batteries when away from the dock and off the generator? My guess is the power supply is converting the 120v power to 12v power. Without the gen, only 12v runs through the system and only those items that can work off 12 will work, even if they are plugged into the 120 circuit. Is that correct?