[Islander]

My other question is about the Tesla destination charger. After reading the manual of the tesla adapter for J1772, it said if the tesla charger blinks red, I need to turn down the power knob on the tesla charger because it would provide too much more amp. But if the charge was led by the vehicle, why would that charger send more power?

Again, deferring to others who know more. But first: from what I've read, Tesla chargers may blink red one time or multiple times, and each blinking rate has a different meaning. I've used my Tesla Tap to charge at a few Tesla destination chargers, and I've never seen a power knob on the charger that could be dialed down. I'm reasonably certain that a Tesla destination charger used with a Tesla Tap can provide no more than 48 amps to an ID.4 even if the charger is rated higher than this. How this "negotiation" works when you're using an adapter, I don't know. However, the Tesla destination charger might provide that 48 amps even if your J1772 adapter is not rated for this much power ... so make sure you're using an adapter rated for more than 48 amps (how MUCH more is a question that's been discussed here). If you're trying to use a Tesla destination charger and it is flashing red ... I personally would not use that charger.

 

[Islander]

Thanks. Just trying to understand the 80% efficiency. So, if I have a 48A EVSE, connect it to a 50A circuit, the car can still only receive up to 40A?

That's my understanding. I believe you need a 60A circuit if you want to use 48A of charging. And, you'd need to hardwire your EVSE. Yes to what N3 said - hard wired 60A is the requirement for a proper 48A installation. You should also be able to set up a 48A EVSE so it can only provide 40A.