If the contacts were damaged and overheating, I would expect the heat (which originates at the interface between receptacle and plug) to affect both sides equally, so it still seems like that’s a possibility here.
I also have the same speculation about cycling. It’s really the only failure mode left. Especially since Jason mentioned seeing some arcing when plugging in the charger, that could damage the contacts and reduce the cycle life.
Of course, if it could be hardwired that would solve the plug issues.
If this connector is arcing when plugged in, that’s an issue because this series of NEMA connector is specifically list as not to be hotplugged. If the charger or any other load is hot on insertion that would explain the issue.
That said, any load on this scale should have some sort of internal load delay, even just a contactor. If the charger is applying full load with the application of power, it needs repaired.
Where would the charger be located exactly and where would a car park to use it?
That being said we have an external run with disconnect that we might be able to use. The old “R/V” plug basically.
Edit: Noticed Tim shared the model we have is obsolete, ditto for the Tesla charger. If we want to support electric car charging at DMS we maybe need to hit reset and see what makes sense and how we could make it reliable and easier to utilize.