I told my wife we must name our next El Captain Stupido. Found the 70 amp breaker off. When I replaced the house battery recently I must have switched it off for safety then never switched it back on. In my defense it takes a contortionist to reach it. I'm still thinking a second house would be nice.
Sadey, I have the same set up on my 59' Marquis. The house batteries give power to my electronics. If I do not run the generator, the inverter (running refrigeration and entertainment) will drain the 2 house batteries. Then after 4 hours I get a low battery message and eventually the electronics completely shut down. What a thing to happen when you are going into a new marina in shallow water!!! Running the generator charges the house batteries and everything runs as expected. Make sure you have a running generator.
Unless they've been upgraded, stock alternators are typically 65 amp units. They shouldn't be having a problem keeping up with the load unless you're drawing more than 65 amps, which is doubtful based on what you said was turned on.
It could be as simple as switch selection or a component failure depending on your particular system (isolator, ACR, etc.). Have you checked alternator output? Just as a quick reference, what does your volt meter on the dash say when you're under way?
Not to be a smart ass because it is obvious by my last post I'm not. To put it bluntly it would appear I ops checked the off portion of the 70amp breaker between the alternator and the house battery. It works perfectly in the off position and as expected will not allow the alternators to charge the house battery. I certainly do appreciate all of the help!!