UMC 5-20 adapter

[ai4px]

Has anyone ever used the 120v 20amp adapter plug? If so, did you ever hook it up to an adapter cable at 220v? Does that work? I think the resistor in the UMC plug sets the current and the car will accept any voltage, is this correct?

 

[TexasEV]

That homemade adapter was a workaround before Tesla made a 6-20 adapter for the UMC. Search and you’ll find several threads from 2013 or 2014 explaining it. If you want 240V now, just buy the 6-20 adapter.

 

[Rocky_H]

@ai4px Yes, this has been a known procedure/workaround for adapters for quite a while. Matching the amps was the important part to get the car the right signaling, but you could mismatch the voltage either way, and the car will happily detect it and use it. I've heard of this being done both directions when there were fewer official adapter types:
With no adapter for a TT-30 (120V 30A), people would make a pigtail to map it to a Tesla 14-30 or 10-30 adapter, giving the 120V supply to the supposedly 240V adapter.
Pigtail from a 6-20 (240V 20A) onto the Tesla 5-20 adapter, and that is feeding 240V onto a supposedly 120V adapter.

The car doesn't care about the voltage difference, but I do seem to recall that it is picky about which orientation it is if you're putting a 120V source (hot and neutral) onto the 240V pins.