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PSA: On CCS1/SAE Combo DC chargers, best to stop the charger BEFORE attempting to unplug

8310 Views 38 Replies 11 Participants Last post by  Sean Nelson
This only applies to DC charging over SAE Combo/CCS1/Combo1, NOT AC charging over J1772. Unless you KNOW the DC charger will EASILY (w/o excessive force, possibly flexing or breaking the locking tang on the handle), it it BEST to STOP charging BEFORE attempting to unplug a vehicle that is actively DC charging.

Possible methods to STOP first:
  • stop button on charger (not the handle)
  • stop button/action in charging network's app
  • stop button on the car's LCD (you may want to wake the car's or stereo's power button)
  • swiping your RFID card/NFC again (necessary on units like the ChargePoint CPE100 ( which don't have touch screens or physical stop buttons beyond emergency stop)
  • last resort: emergency stop button, if any

See Experience with Electrify America, as to why. If you don't, you may break the locking tang on the handle and you might even cause massive arcing if charging hasn't stopped when you pulled out. Or, the broken tang can be a hazard for the next user OR, the handle might be rendered unsuable until it's repaired.

There's been discussion of this before. Examples at Fast charger locked to my car and My Experience DC Charging overnight at hotel. There seems to be confusion, which is no surprise given that it can be different than J1772 AC charging on GM and many other vehicles.
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I believe the Proximity Pilot pin on J1772 is used to sense when the button on the plug is pressed (latch released), opening the circuit on the AC power pin(s). Since DCFC uses the DC power pins, the latch would seem to be relegated to holding the plug in place. Proximity pilot is likely only used to detect if the plug is properly latched before allowing the DCFC session to proceed with initialization and authentication.

I have always understood the EV or EVSE (or app) must be used to end a DCFC session before attempting to remove the plug. I believe this is described in the CCS specifications.
I believe the spec is for the EVSE or EV to discontinue the flow of electricity before removing the handle. If the proximity sensor is active, it likely signals to the EVSE to stop, which takes a second or two. With AC charging, the proximity sensor disengages the power at the pins on the handle and is instantaneous.

I don't think I have seen a DCFC that instructs to stop a charge using the handle, it seems dangerous if one assumes the same timing that AC charging does.
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FWIW, now that CCS Combo 1 Adapter is officially for sale Teslas in the US (the vehicle itself must also have the proper hardware), per CCS Adapter for North America, Tesla's car-side software says:
"CCS cable button not intended to stop charging
Use touchscreen or Mobile App to disconnect"
That could lead to some interesting scenarios.

A few times, I have stopped a session at EA by pressing/holding the button on the handle. It apparently sends a signal to both EV and EVSE to terminate the session.

The CCS standard covers this, as I recall leaving it to either the car or EVSE to initiate termination, and sending signals to do so. It may just be the proximity pilot circuit like J1772, or it may be control pilot signaling. My guess is control pilot and Tesla didn't implement CCS fully to recognize end of session signaling in the protocol implementation, thus the warning. Tesla already follows the J1772 protocol, so proximity pilot signaling is already implemented.

Leaving it up to humans seems like a potential issue.
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