Hi Everyone, this is my first post. We just purchased a 1997 Rockwood 1620 Tent Trailer for our young family. Our tow vehicle is a 2012 GMC Acadia without the tow package. The previous owner never had a battery on the trailer as they always plugged in. I have just added a battery, but need to figure out how to charge it. The Converter does not charge the battery, and I have a 4 pin plug from the Acadia and a 7 pin adapter to plug into the trailer. Will the 4 pin plug provide power to charge the battery? If not what are the best or cheapest options to charge the battery?