Departure Time (preconditioning) and stress to HVB electronics

[SpaceEVDriver]

Agreed.
In my case, the EVSE I use for the Mach-E is Aerovironment RS which has a fairly loud audible "clunk" for the contactors so I always listen for it to shut down and it happens very fast. Quicker than I can pull the connector out of the socket for sure. Some other EVSEs might have a delay which is odd because it should be immediate. I will do some testing with various manufacturers and see if any behave differently. A 2 second delay is not okay. It should be 20 milliseconds really...

I haven't timed mine, so when I say "a couple of seconds," I'm not being precise, nor even terribly accurate. I really mean that I press the thumb release and wait for the sound.

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[scoopman]

[l

What is below the CCS charging flap? It looks like a piece of paper stuck beneath it.Did the CCS flap break?

Good question! That's a little piece of foam that I keep there for public charging situations. When I'm in a place where someone could hit my charging door, I take the little piece of foam and put it like so to further prevent the door from getting hit and denting my fender...

 

[Mach-Lee]

OK, here’s my engineering input. Like others have said, when you press the latch button on the J1772 the charger should IMMEDIATELY stop. An arc will only happen with the first disconnect, so it doesn’t matter if the car’s contactors open after a delay because the current was already stopped by the charger and/or EVSE.

Again the arc will only happen where the disconnect is first made, so at the J1772 connector pulling out if you yank it fast. Not in the HVBJB. So I don’t think this has anything to do with the failures unless the pack contactor is opening faster than both the EVSE and J1772 disconnect, and before the charger stops drawing amperage.

Ideally the charger will respond to the dropped proximity signal immediately so the current is zero when the EVSE contactor opens a few milliseconds later (no current, no arc). Pausing for 1 second before pulling out the J1772 should be plenty of time.

EDIT: J1772 spec is to shut down charging in less than 100 milliseconds, so there shouldn’t be any issues here unless you are super quick pulling out. You don’t need to wait 2 seconds.

 

[TonyaE]

I need help with understanding the preconditioning (set departure time) vs remote start. I plan to charge from 9pm-6am. I leave at different times everyday for work. Would I set departure time for 6am? I may not leave until 10:30 am. Do remote start 15 minutes before I leave or will it stay preconditioned from 6am departure schedule?

 

[Maquis]

OK, here’s my engineering input. Like others have said, when you press the latch button on the J1772 the EVSE should IMMEDIATELY drop the voltage. You should hear it click as soon as you press the button. If there is any kind of delay (more than like 0.5 sec) your EVSE may be defective. An arc will only happen with the first disconnect, so it doesn’t matter if the car’s contactors open after a delay because the current was already stopped by the EVSE.

Again the arc will only happen where the disconnect is first made, so at the J1772 connector pulling out if you yank it fast. Not in the HVBJB. So I don’t think this has anything to do with the failures unless the pack contactor is opening faster than both the EVSE and J1772 disconnect, and before the charger stops drawing amperage.

Ideally the charger will respond to the dropped pilot immediately so the current is zero when the EVSE contactor opens a few milliseconds later (no current, no arc). Pausing for 1 second before pulling out the J1772 should be plenty of time.

EDIT: J1772 spec is to open/shut down in less than 100 milliseconds, so there shouldn’t be any issues here unless you are super quick pulling out. You don’t need to wait 2 seconds.

Exactly correct. I’m also an EE and wanted to comment, but I was too lazy to take the time to formulate such a response. Thanks for spelling it out.

 

[Jimbo]

OK, here’s my engineering input. Like others have said, when you press the latch button on the J1772 the EVSE should IMMEDIATELY drop the voltage. You should hear it click as soon as you press the button. If there is any kind of delay (more than like 0.5 sec) your EVSE may be defective. An arc will only happen with the first disconnect, so it doesn’t matter if the car’s contactors open after a delay because the current was already stopped by the EVSE.

Again the arc will only happen where the disconnect is first made, so at the J1772 connector pulling out if you yank it fast. Not in the HVBJB. So I don’t think this has anything to do with the failures unless the pack contactor is opening faster than both the EVSE and J1772 disconnect, and before the charger stops drawing amperage.

Ideally the charger will respond to the dropped pilot immediately so the current is zero when the EVSE contactor opens a few milliseconds later (no current, no arc). Pausing for 1 second before pulling out the J1772 should be plenty of time.

EDIT: J1772 spec is to open/shut down in less than 100 milliseconds, so there shouldn’t be any issues here unless you are super quick pulling out. You don’t need to wait 2 seconds.

Ya, my Ford Mobile Charger takes a bit more than 100ms, FWIW

Audio waveforms of two unplug events (top was measured at car charger port, bottom was next to EVSE, to verify my ears weren't deceiving me regarding where sound was coming from)
Noise at:
~0s is me depressing the disconnect trigger
~1.25s is the EVSE contactor opening
~1.5s is the car's contactor opening
~2.9s is another contactor in the car opening?

 

[Maquis]

Did they update


Ya, my Ford Mobile Charger takes a bit more than 100ms, FWIW

Audio waveforms of two unplug events (top was measured at car charger port, bottom was next to EVSE, to verify my ears weren't deceiving me regarding where sound was coming from)
Noise at:
~0s is me depressing the disconnect trigger
~1.25s is the EVSE contactor opening
~1.5s is the car's contactor opening
~2.9s is another contactor in the car opening?

The important thing in this context is that the EVSE acts before the car!

 

[Jimbo]

The important thing in this context is that the EVSE acts before the car!

Ya. Also, perhaps the EVSE's got a solid state relay and a contactor. The relay could be opening quickly (and silently), followed later by the contactor, but I'll defer to you electrical engineers on the likelihood of that.

 

[scoopman]

Thanks for all the excellent responses -- it's good to have electrical engineers on-call, and to know that my poor J1772 unplugging practices probably did not harm Mach N Cheese!

 

[Mach-Lee]

Ya. Also, perhaps the EVSE's got a solid state relay and a contactor. The relay could be opening quickly (and silently), followed later by the contactor, but I'll defer to you electrical engineers on the likelihood of that.

I had to read J1772 again, but here's the sequence of events when the vehicle is charging and the latch is pressed:

1. Pressing the latch opens the S3 switch in the handle, which adds a 330Ω resistor to the proximity pilot (PP) circuit
2. The vehicle detects the drop in voltage on PP and reduces charger output within 100 ms (current flow is now essentially zero)
3. After power conversion is stopped, the vehicle opens the S2 switch which increases the control pilot (CP) line voltage
4. The EVSE detects the increase on CP and disconnects AC power (contactor opens)
5. Disconnect is safe any time after #2 is complete.

Note, the EVSE gets the signal to shut down from the car, not the latch switch (I was wrong about that earlier). This way it will wait to open its contactor until after the current has stopped. Therefore there will be zero arcing anywhere during the disconnection process as long as the user waits 100 ms. It is unlikely that most people will be able to pull the plug out faster than 100 ms.

Also note that the vehicle may delay opening the EVSE or its own contactor past 100 ms, remember the current switching off in the charger is silent and happens first. You will hear clicks after a second or two, but you don't have to wait for those because the current has already stopped.

In summary, you are fine pressing the latch button and pulling out at a normal speed even if you hear clicks afterwards. The J1772 standard is designed to be pretty foolproof. You only have to press the charging stop button before disconnecting a L3 DC charger.

 

[JohnFoxeSheets]

Thanks for all the excellent responses -- it's good to have electrical engineers on-call, and to know that my poor J1772 unplugging practices probably did not harm Mach N Cheese!

I just did some really quick checks with my 48A ChargePoint Flex EVSE and my 2022 GT.

1) I plugged in the J1772 connector and let the car go through its charging-start process. Once everything quieted down (I probably waited a minute or so), I pressed the latch button on the J1772 connector and waited until I heard clicks from the EVSE. While I didn't time it (good idea to use audio @Jimbo), I estimate it was a good second before I heard connector disengagement. I tried this several times and always had the same results: about a second from button press to EVSE clicking noises. I also confirmed that the lights of the EVSE changed at the same time (from Charging to Ready To Charge) as the clicking sound.

2) I repluged in the J1772 connector, waited a few seconds (the car seems primed for charging at this point and quiets down almost immediately), then pressed the unlock button on the MME in the center of the ring charging indicators next to the J1772 socket. They flashed white for a second or two and then happily went back to charging. For L2 charging it seems this button doesn't do anything constructive.

3) I repluged in the J1772 connector, waited a few seconds, then pressed the latch button on the J1772 connector and immediately pulled the connector from the socket and during the disengagement on the connector from the car I heard the clicking of the EVSE, indicating that the removal of the J1772 connector does what it needs to do: gets the EVSE to stop providing power to the car, just as the J1772 spec says it must. This fail safe mechanism appears to work just fine.

4) I tried pressing the latch button, waiting the requisite second for the EVSE clicking to occur and charging to stop, left the J1772 connector in the socket and then let go of the latch button: the EVSE once again started providing power to the MME. I tried this a couple times with the same results.

So yeah, the net of all this is that the unplugging process appears to be robust to normal user behavior. Of which I'm glad because it never occurred to me that it would be anything else!

 

[Astraea]

You are absolutely correct @Blue highway @ZuleMME @JamieGeek. Today I Learned something!

The problem is that normal people who will be buying this car, and aren't engineers who read the proximity pin J1772 spec, will not know this. They will do what I did, and just press the button and pull the plug out.

I'm not that dumb, and I had no idea that you need to hold the latch for about 2 seconds before yanking. Ford's owners manual doesn't say this either (not that anyone reads the manual).

Experiment #2 with your suggestion, confirmed that this works, and is what I'll be following if I ever need to unplug from Mach N Cheese while charging. I still say this should be locked when current is flowing -- this is how the ID.4 works and it sounds like the better human interface solution here.

So what you're saying is I shouldn't keep grabbing the plug like a life line and ripping it out from my car as fast as possible anymore? ?

 

[BigMach-E]

Hmmm, I am using the Ford Mobile charger 95 percent of charge sessions. I haven't been listening for any disconnect sounds. Since getting my car back after HVJB and BECM replacement, I do not think I have disconnected during a active charge/preconditioning session (using latch or button). I have used the button on the car and unplugged on L2 post charge and unplugged with the white lights circling (battery at top of charge state, ring unilluminated prior to button press and disconnected). Out of an abundance of caution, I have turned off preconditioning. I don't wish to chance things, so I haven't attempted to stop a charge session on L2 while occurring. I have also pressed the latch on the EVSE every time prior to disconnect, but have not waited for disconnect sound prior to pulling.

I think I have unplugged on public L2 once while active charge since the HVJB and BECM, and I pressed the button on the car and the EVSE latch, but since it was VOLTA, there was no indication of disconnect, and wasn't listening for disconnect.

When the lights are white/circling, does this means safe to disconnect?

 

[Drea89]

I was confused and interested in this thread because mine behaves differently, and after seeing the video i noticed that NA and EU have different plugs!

i still believe it's a software issue because on mine if i hit the lock on any level of charging it stops charging and the ring turns white so it should do the same no matter what type of connector they put on the car.

here a pic of the different plugs for reference:

 

[67 Stang Convertible]

You are absolutely correct @Blue highway @ZuleMME @JamieGeek. Today I Learned something!

The problem is that normal people who will be buying this car, and aren't engineers who read the proximity pin J1772 spec, will not know this. They will do what I did, and just press the button and pull the plug out.

I'm not that dumb, and I had no idea that you need to hold the latch for about 2 seconds before yanking. Ford's owners manual doesn't say this either (not that anyone reads the manual).

Experiment #2 with your suggestion, confirmed that this works, and is what I'll be following if I ever need to unplug from Mach N Cheese while charging. I still say this should be locked when current is flowing -- this is how the ID.4 works and it sounds like the better human interface solution here.

I've owned my car 9 months and did not know that. I appreciate the info!!!

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