The EVSE is the unit most people call the charger you install in your garage. It is not actually a charger, the charger is in the truck. The EVSE is simply a switch that turns on 240V to the truck. There is a communications link in the J1772 plug that allows the truck to read the supply voltage and maximum current capability, and the truck can tell the EVSE when to turn on. The 240V to the truck can be turned on without the truck actually charging the high voltage battery. That 240V is converted to DC to run the HVAC system and to also charge and maintain the 12V battery, that is in addition to the ability to charge the main battery.EVSE?