It would be helpful if you could add the year of your coach to your signature. Now that I asked for that, depending on when WRV changed to the Vansco system is what counts. Their literature shows that 2004 was the first year, but they probably started the switch in late 2003 model year. If you have the Vansco system, then your "big boy" relay is probably bad. Look for light 19 on the Vansco module to be light when the house batteries are charging. Do a search for more information.
It sounds like you don't have the Vansco system, which means that you should have an Echo charger. There many posts on problems with the Echo charger, do a search.
2007 Limited SE 40fdts
Las Vegas, NV