Sounds strange, because as you say diode usually fail open circuit. It would be easy for you to check continuity through the splitter, and I'd suggest this as the first step. I can't see that it would be a negative fault.
I found the fault and probably what caused it! Well defiantly what caused it. The ECS 163 splitter is based on Mosfet's
not Diodes. When the unit fails it will not/may not fail safe. IE When/if the unit fails it will allow current to flow from the battery connection posts to each other and not from the alternator connection post to the others. The engine fan can then pick up a + supply from the battery(s) direct and not from the alternator as the circuit designed to do.
Removing the unit and taking it apart reviled that 3 of the mosfet's have failed, burnt out, poohed themselves. 😀
I was in the bow locker the other day cleaning it out, moving some tools about and tidying up before we fly back to the UK for a few months. Years ago I installed an isolator switch on the Bowthuster + feed so I could isolate it when the boat is out the water and I am cleaning the prop or replacing the anode. Due diligence I turned the isolator off while working in there...... Then forgot I had. It appears that when you then try to operate the bowthruster when re-securing your lines a few days later the splitter tries to pull 60-70 Amps from the other batteries via the mosfet's. Which then get very hot!!!! Normal diodes wont do this. Perhaps thats why they have discontinued the Quick ECS 163 and you cant get one from SVB! Self Inflicted wound it would appear! Ant.
