It's not even a power converter, it's just some contactors and a microcontroller that tells the EV what sort of power source it is. The EV talks to the micro and if the input power is compatible the contactors close and deliver AC directly to the EV. The charger onboard the EV takes that AC input and converts it.
> It’s unwise because there is no way for a passive cable or adapter to tell the car to limit current to anything below 80A.
Yes there is, the adapter just passively adapts all 5 pins. The J1772, CCS Combo 1, and NACS are all pin compatible. The EV has an ECU that can detect what is plugged by sensing the configuration on those 3 pins and negotiate accordingly. For older Teslas to support the CCS Combo 1 adapter they require an ECU upgrade. The adapter only needs to passively connect all 5 pins.
If your dumb adapter is actually rated for 80A and the J1772 protocol is never extended to allow more than 80A, you’re fine.
If your dumb adapter is rated for less than 80A, but your car and charger negotiate more than the rating of your adapter, you may have a problem. See, for example:
Are there any EVs besides that Model S/X that can L2 charge above 11.5kW?
If everyone adopts NACS then this won't be an issue because even the lower end adapters support 11.5kW. The longer it takes for North America to standardize, the greater the possibility of your hypothetical scenario becoming a reality.
