I have the UMC charger plugged into a NEMA14-50, 240V 50A circuit - no problems. It is slightly warm when charging, but not at a level that would concern me.
Mine's plugged in 24x7 outside (I did pull it inside when I expected a lot of snow so I didn't worry about not being able to see the cable while using the snowblower). About 6 months now, no issues.
Mine's plugged in 24/7 as well, no issues at all. What's in that blob is basically an over-sized ground fault interrupter with a detector for the signal coming from the car. The relay coil is probably what's giving off the most heat.
Actually, it's a GFI extension cord with a "pilot" signal going to the car telling the car the maximum current it can draw.
Putting a meter to the Tesla connector, the UMC will not energize the power pins unless the pilot signal pin has been pulled to ground via the diode and resistor. So information is really going to and from the car at the same time.
Yes, that's correct. I was describing the most basic implementation of a charger like the one I built here. If you signal the max current to the car and ignore the response from the car, the car will start charging. The reverse is not true.
I have a RFMC plugged into a NEMA 14-50 for the past 2 years. It does not get warm, the only current flow is for the LED's.