The EVSE is a glorified RCD/GFCI cord with a contactor that turns on power, so the cord is dead until that happens. It also generates a signal that tells the ca

The EVSE is a glorified RCD/GFCI cord with a contactor that turns on power, so the cord is dead until that happens. It also generates a signal that tells the car how much power it's allowed to draw; the EVSE is configured at install time to know what size breaker feeds it upstream, so it tells the car not to trip that breaker, but the EVSE has no means of actually enforcing such a limit. There's some basic negotiation between the EVSE and the car, to decide when the plug is inserted and it's OK to turn on the contactor. The AC power passes straight through the EVSE, unaltered in voltage, current, or waveform. The EVSE may monitor the current to perform logging, and the EVSE is required to monitor the AC imbalance like any other RCD/GFCI does so it can open the contactor if there's a ground fault, but that's it. It's just a smart extension cord, basically. The charger is in the car, and is the component that actually converts the AC from the grid to DC for the batteries. The charger is what has all the silicon (or these days, probably gallium nitride?), and the inductors and capacitors and stuff to actually transform the power from one form to another. It changes the voltage to match whatever the battery needs at the moment. It controls its own DC output to match the battery's needs, and it limits its own AC input according to the signal from the EVSE so it doesn't trip the upstream breaker. The charger is also responsible for immediately turning itself off, reducing its input draw to zero, within a few milliseconds of someone pressing the latch of the EVSE connector handle. This indicates they're about to pull it out, and the contacts aren't designed to handle arcing, so the charger is required to drop its current _very_ quickly, allowing the contacts to be separated without creating an arc. That signal (called PP) is produced in the handle itself, there's just a tiny switch underneath the latch. The handle is technically part of the cord which is technically part of the EVSE, but the EVSE has no responsibilities related to the signal, that's all on the charger. If the SAE hadn't mandated that the EVSE perform RCD functions, it could be replaced by a literal extension cord. Many small DIY EVs do precisely that; the charge cord is the exact same one you'd use to run any appliance. It works just fine. But even small DIY EVs have a real charger too, which converts the AC from the cord to DC for the batteries. The charger plugs into the cord, but the charger is not the cord.