Batteries, fridge, batteries and solar,batteries batteries batteries...
Wuck, et al,
(Unintended pun)
Your many suggestions come wth valid arguments, are well appreciated and enthusiastically received. And here I have been trying to do this on my own and having no fun. I may even learn something about electricity and the scientific method.
My sense is, that the battery component and its condition must be resolved before actively addressing other implications proposed. One thing at a time.
Historically, last fall the batteries tested positively in Missoula, Mt. at a large RV service center. They also tested positive in April at 4WCs Woodland factory (particularly maddening as a few hours later the surge cycled wildly while dry camping at Harris Ranch a few miles down the road). A couple weeks later in early May (and at wits end), they were again checked at Interstate Battery, Carson City Nevada. Then, untrustingly, again a few blocks away at an RV Solar specific repair shop.
Of course, all positive results. At Interstate particularly, I was practically begging them to install new batteries waving my credit cards in desperation. They had every opportunity to sell the store but would not give those damn batteries a poor grade. Sooner or later I'll have to trust that at least one of those places knew what they were doing. Today we are applying Happyjax suggested "real world testing method" and hope to put and end to suspicions of inept testing and move on. All that said, after two years of fighting this problem, surly, they must be damaged by now.
While performing this "mother of all tests", there are at least two, if not three issues still on the table, battery charging, refrigerator performance and wire gauges.
SOLAR
Both forum input and Tri-metric historical data substantiate insufficient solar input
and possibly the battery separator as inadequate. I have not taken actual measurements from the separator as the Tri-metric always indicates an increase in voltage (up to 14.2) and amps with the vehicle running. That seems enough of an affirmation to remove it as a problem. As for panel capacity, 4WC and others have suggested replacing the current panel (under 100w) with a 160w unit. I'm thinking, why stop there, and will likely jump to 200w which will probably be next year's recommendation anyway. We can easily dry camp for 7-10 days and not always with direct sun. My wife is a gourmet and loves that fridge...OK, so I like to eat.
Too much is not a problem, is it?
Incidentally, the battery/controller/charger/separator compartment is spotless. There is no corrosion detectable and unless there is a faulty connection I cannot see, all else feels snug & tight.
REFRIDGERATION
Honestly, this has been my primary suspect all along. Venting is terrible (what were they thinking?). Dry camping in Furnace Creek, Death Valleys we chanced to be sandwiched between 2-4WCs (Hi Camelracer). Both campers had literally, square footage of fridge venting. How do they keep their interiors clean and heated? ....yea, but they don't have battery problems).
OK, I'm ready to cut holes in my wall to keep my wife's fridge running. But,
we tend to seek out dirt/gravel roads. Are there dust free, or fan activated vents that won't overtax the new batteries and new 200w solar panel?
Or, I could save a few thousand $$$ and buy a Honda generator....
Kidding........sort of.
If the fridge is bad, I'm not sure what the answer to that problem may entail.
So seriously, I'm looking for venting but want to keep dust infiltration down and a warm cabin in freezing weather. So far I've only seen plastic or sheet metal louvered panels and am open to all suggestions.
And then there is wire gauge question. Its doubtful that any of the camper wiring is too heavy but is it too small and perhaps choking what little current is available? Is it worth increasing the some of the critical circuitry to improve charging or distribution?