Level 2 charger, what is in side?

Discussion in 'General' started by JOHN PHILLIPS, Sep 8, 2019.


    JOHN PHILLIPS New Member

    From what I can see a level 2 charger is an extension cord between a 240-volt line and the car with a fancy plug on the car end and maybe a switch and current sensing display in the box on the wall. A good one may have a delayed start. What am I missing? Tesla has some other part the opens the car charging port cover. I do not know if anything else is special.
  2. KiwiME

    KiwiME Active Member

    At minimum they have a residual current detector, a power contactor and a controller to generate a Control Pilot signal for handshaking with the EV. Go to OpenEVSE and you can see all the parts.
  3. bwilson4web

    bwilson4web Well-Known Member Subscriber

    The pins are:
    • pilot signal - uses a resistor network and diode to communicate between car and EVSE
    • presence signal - uses a resistor to indicate it is connected
    This may help explain more:


    It has a small bluetooth transmitter that lets the car know to open the charging port cover.

    Bob Wilson
    electriceddy likes this.
  4. I took apart a couple of Chinese 32A EVSEs :
  5. bwilson4web

    bwilson4web Well-Known Member Subscriber

    One minor mistake is the latch on the J1772 takes a resistor out of the "presence" line and signals the car to shut everything down. As for unlocking the connector, well my experience is that seems to be a gap in spec but likely car specific. Also, it doesn't really address adapters like the Tesla-to-J1772. But the "presence" line works quite fine.

    Bob Wilson
    Last edited: Sep 12, 2019

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