I have purchased a 2004 catalina 350 and the prior owner has been a great help. I want to confirm something because it does not make sense to me. Supposedly, when plugged into shore power, there is no transformer that converts 120v to 12 v. Instead, you must use shore power to charge batteries which in turn powers the 12 volt. In short, dead batteries even when plugged into shore power means no 12v electronics. Does this mean that when plugged into shore power and going home until the following weekend, you leave the battery charger on all week? Thanks for any advice.