Departure Time (preconditioning) and stress to HVB electronics

[SpaceEVDriver]

On mine, I push the latch button on the L2 charger, wait to hear the relays fire, and then pull the plug out. If you are pulling the J1772 out with it still delivering current, arcing will take place somewhere.

There shouldn't be an arc. The proximity pin (12V, <13A) is shorter than the others and when it's disconnected it cuts power from the EVSE and the vehicle. The thumb button on the plug disconnects the proximity pin, so *in theory* it should do the same thing as pulling the plug. However, I like to give the mechanical contactors time to disconnect before I unplug, which is why I used the thumb button to disconnect before pulling the plug.

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[scoopman]

On mine, I push the latch button on the L2 charger, wait to hear the relays fire, and then pull the plug out. If you are pulling the J1772 out with it still delivering current, arcing will take place somewhere.

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.

 

[Blue highway]

There shouldn't be an arc. The proximity pin (12V, <13A) is shorter than the others and when it's disconnected it cuts power from the EVSE and the vehicle. The thumb button on the plug disconnects the proximity pin, so *in theory* it should do the same thing as pulling the plug. However, I like to give the mechanical contactors time to disconnect before I unplug, which is why I used the thumb button to disconnect before pulling the plug.

Theoretically, yes. the relays should drop first. However, I can easily pull the plug out before the relays fire if I'm not thinking about it. In my car it takes ~2 seconds so I give it that time.

 

[scoopman]

There could be a valid concern here but we really don't know exactly what is happening during that situation you describe.

The SODBM does the L1 and L2 charging and it somehow has a way to isolate the circuits (Charging the HVB and LVB while also providing power to high voltage loads such as the A/C compressor or PTC heater.

The WSM actually says the car is able to pre-condition while on L1 by drawing power from the EVSE and the HVB which is new for Ford. I don't believe the Focus Electric has that capability.

That being said.....I routinely approach my car each morning while it is pre-conditioning and I unplus the EVSE as normal. So far I haven't had any issues with arcing but of course I wouldn't really be aware of anything until the failure actually occurs. ???

Here is the text from the WSM about unplugging....

This snip assumes that the user knows what I show above in my video (which I did not!) that you need to press the latch, but not tug until you hear charging stop. This is a user experience issue, the action in my video above is not what most people would do.

 

[scoopman]

There shouldn't be an arc. The proximity pin (12V, <13A) is shorter than the others and when it's disconnected it cuts power from the EVSE and the vehicle. The thumb button on the plug disconnects the proximity pin, so *in theory* it should do the same thing as pulling the plug. However, I like to give the mechanical contactors time to disconnect before I unplug, which is why I used the thumb button to disconnect before pulling the plug.

Gotta wonder if the engineers designing this system assumed that real customers would wait the 2 seconds before unplugging, and didn't properly test enough during development what happens if you just yank it out.

 

[Kamuelaflyer]

I read it and I don't think it matters what the car is doing when you unplug.

Its just part of the J1772 spec: When you grab the latch the EVSE is supposed to disconnect--its a safety feature. All of my cars with a plug have operated that way.

You’re correct, it doesn’t matter. That’s how I disconnect the charger when my car is preconditioning. Works flawlessly.

 

[Bryan_GTPE]

Thanks for all this info, I had this happen once, I did not realize you needed to hold the button for 2 seconds. I don’t precondition often, so I was hitting the Stop Charging button on the FordPass app right before I went into the garage and the charger would be disconnected and then I just unplugged. I have been afraid of disconnecting while power is still flowing so I always hit stop charging in the app at other times prior to disconnect. Now wonder how many of these events will damage the HVJB?

 

[SpaceEVDriver]

Gotta wonder if the engineers designing this system assumed that real customers would wait the 2 seconds before unplugging, and didn't properly test enough during development what happens if you just yank it out.

Yep. This is a common issue with unit and edge considerations in engineering. Until people not familiar with the device/software design process use it, the designers/engineers don't know all the possible ways it will be (mis)used.

Literally the first time I plugged in the car, I immediately unplugged it to see what would happen. Then I heard the contactors disconnect and realized (because of my history with EE and other engineering) that I needed to let the mechanical disconnections happen before I fully unplugged the vehicle. There should be an instruction sticker in the charging port that describes how to do this. Nobody reads the manual and the manual doesn't describe this action either. In fact, the manual is mostly filled with [WARNING] paragraphs that just overwhelm the reader so they ignore all of them.

 

[mmap]

Let's think about this contactor... it's true, small arcs could cause it to stick over time. Another thing that can cause it to stick is heat caused by excessive current. Which of these conditions is more likely to be present in a GTPE?

 

[scoopman]

Thanks for all this info, I had this happen once, I did not realize you needed to hold the button for 2 seconds. I don’t precondition often, so I was hitting the Stop Charging button on the FordPass app right before I went into the garage and the charger would be disconnected and then I just unplugged. I have been afraid of disconnecting while power is still flowing so I always hit stop charging in the app at other times prior to disconnect. Now wonder how many of these events will damage the HVJB?

It can't be good for it. I did this many times during preconditioning without thinking about it. Whoops.

 

[Jimbo]

I've always held the button until I heard the clicks, as, while I presumed Ford designed their system such that a quick unplug didn't damage the contactors/electronics, I didn't want to find out what happens if they didn't.

Not at all blaming the user: if Ford expected most users to hold the button for 1-2 seconds before unplugging, that's laughable

 

[generaltso]

It can't be good for it. I did this many times during preconditioning without thinking about it. Whoops.

Don't worry about it. The thumb latch and the proximity pin have you covered. It's built into the J1772 spec to prevent arcing, even if you don't wait 2 seconds.

 

[SnBGC]

This snip assumes that the user knows what I show above in my video (which I did not!) that you need to press the latch, but not tug until you hear charging stop. This is a user experience issue, the action in my video above is not what most people would do.

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...

 

[Mach-e4x]

I use the Ford Pass app to stop the charging process and take my time to unplug the Grizzle EVSE.

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