Truth.I've found that there is no good time to run a generator in a quiet anchorage
This is typical. Although it is an expensive, disruptive project, rebuilding your freezer and fridge with vacuum-insulated panels would make a huge difference.All lights are LED. The TV isn't on much. The refrigerators are the biggest factor. They account for 80% of the daily amperage draw.
Shorted cells in FLAs are a very common failure mode. As you describe the 6-cell, 12-volt battery becomes a 5-cell 10-volt battery. The charging sources that are present, blissfully unaware of the change in design voltage, try to bulk charge the shorted battery, which results in electrolysis -- with the battery giving off hydrogen and oxygen gas, and odoriferous sulfur gases. In rare cases the battery will explode when an adjoining cell shorts in the presence of hydrogen.On the other hand, one of my FLA batteries shorted out after 5 years. The charger saw that as a low battery and just kept pumping. All 3 house batteries boiled over. It didn't cause a fire, but it seemed like it could have. Over the last several years the same thing happened to 3 other boats on my dock. In each case the FLA batteries were 5 years old.
I replace FLAs after four years regardless of their apparent condition. Otherwise, it's like watching a bad movie where the ending is obvious.
AGMs are somewhat less prone to shorted cells.