"Maybe you had a different background"
Apparently so, Richard. When I tried a quick web search for "Reverse Power Technology" it came back with zilch. Then again, when I first read Jules Verne and tried to find out what "fuming azotic acid" was, no one had heard of that either.
Times and terms change so quickly.
A reverse current
relay sounds to be simply a special case of a relay, with perhaps two balanced coils to make it function as a voltage comparator? That would count as clever steampunk engineering these days. By the time I was being taught about these things (voltage comparators) there were ICs being used for the purpose. Outside of the generator
industry...nope, never met one.
Interesting ("curiouser and curiouser, said Alice") programming that is being applied to those compressors. I have no idea of why they would make it so complicated (in the name of energy savings??) but it makes me think of BMW and Audi. Very cleverly engineered, but sometimes that just makes them high-strung and full of new failure modes. A Willys Jeep didn't need sensors to monitor
the sensors, much less have a hundred of anything hooked up in it, except maybe the total parts
count for the engine.
Given the popularity of the Danfoss units and the, ah, questions about the controllers, it would seem that a complete plug-n-play aftermarket replacement would be the best solution. Improve the logic, improve the sensors, make it more robust. To a large extent "a board is a board" these days, and having an entire new module made up might be nearly the same price
as trying to patch the existing one with "extras". That also allows one for microprocessor to decide how to run it, based on temperature, or charging
sources, or ambient daylight, or any other criteria at the same time. Of course that would be a risky business proposition, since Danforth and others could easily change their design and knock a third-party out of the market, if you came up with something that worked better than what they have.
It could just be the problem is poor technicians doing the installs, in a way that leads to overheat problems. After all, gen-you-whine factory trained AC techs routinely send something like 1/2 of perfectly good AC compressors back to car manufacturers every year. That's a 50% failure rate on diagnostics, and boat techs? Why would they be any better?