As much fun as it would be for Ted and I to debate the design criteria of these devices, I suspect that not many on the forum would want to read it. So, I will go back to my original premise and share my conclusion.
1. After my relay failure and noting hundreds and probably thousands of posts documenting failure of the battery isolation relay (generically referred to as Trombetta) in multiple MH forums, I set about finding a specific brand and part number that I can be confident will give me better service life than the ones that often fail within a very few years.
2. There are two primary failure modes. Failure of the coil that latches the two relay contacts and failure of the contacts that actually transfer the charging current from the alternator to the house batteries. I don't consider either failure mode to be acceptable within a 3 to 5 year time frame which seems to be the normal experience.
3. I received only three responses in the short time that this thread has been up and I thank the forum members that responded to my specific request.
4. After a couple of more hours of research on websites of highly regarded control component manufacturers including Trombetta, I chose to order the White Rodgers 586-108111 Solenoid 15V 200/600 Amps ($56) that camperguy99 suggested. Hopefully it will be several years before I know if my choice was a good one since even the OEM part should get a few years before failure.
https://www.amazon.com/Emerson-586-1...64&s=hi&sr=1-1
5. For others who prefer the Trombetta brand, I found that the now offer an upgraded version of the original with silver plated contacts. What I was not able to confirm was whether or not they upgraded the 12V coil.
6. Note: many newer motorhomes don't use the Intellitec BIRD and seperate isolator relay that this post is related to.
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