At the end of last summer we noticed the interior lights were diming when too many were on, even though we were hooked up to 110v. Over the winter I replaced the two deep cycle batteries to no avail. If you turn on an interior light the other lights become noticeably dimmer. When I disconnect from 110v, all lights go out (the batteries being brand new are fully charged). A fellow Airstreamer suggested it could be the converter is not charging the batteries. But after unplugging from 110v wouldn't there be some power from the batteries? Don't want to spend the money troubleshooting the entire electrical system. Any suggestions?