You should check the battery for level in each cell and add distilled water if needed. the battery may not be good.If you can plug into a house circuit with adapters to convert your 30 amp to regular house outlet it should charge your battery. When you are plugged in your converter provides 12volt and charges your battery. when plugged in to power your battery should be receiving about 13.6 volts which you can check with a meter.Your tow vehicle may charge it depending how your 7 pin adapter is wired.