[nomel]

Yeap. Level 1 and 2 chargers are literally just relays, with a bunch of fluff attached.

The DC fast charger has smarts, with circuits that measure resistance, temperature, etc, to keep things from melting.

[chinabot]

Yeah, most of this circuit is fluff for comms and networking, Basic EVSE such as J1772 can be implemented with a relay, comparator and square wave generator.

[outworlder]

I think they have to be somewhat not dumb and communicate with the car before it will close the traction battery contactors?

[zrail]

A little bit but not much. They're a contactor, a GFCI, some current sensors and limiters, a small section to determine if the EVSE is operating at L1 or L2, and a small microcontroller to control it all. They're very simple devices.

Edit: info from here: https://www.barbouri.com/2017/03/10/diy-open-evse-v4-23/

[thescriptkiddie]

The signaling is surprisingly simple. There is no active negotiation, the EVSE just outputs a PWM signal to specify how much current the car is allowed to draw, and the car uses a variable resistor to request the power be turned on or off.

https://en.wikipedia.org/wiki/SAE_J1772#Signaling