Departure Time (preconditioning) and stress to HVB electronics

[scoopman]

As many of you know, I just had my High Voltage Battery Junction Box replaced. It failed in some way, perhaps through electrical arcing, and was "stuck" closed, cutting off the HVB from the rest of the car. This was not a fun experience.

Since getting my car back, I've been very aware and thinking of whether I ever remove my L2 charger (as an example) while it is still delivering current -- and I have at times when my car was in the process of preconditioning and holding temperature for a departure time in the morning. I wonder whether removing the L2 charger while it is delivering energy may put undue or unplanned stress on the part that failed.

Unfortunately, Ford seems to be making it easy to have unplugging L2 while under load unavoidable:

• Departure times are the only way to precondition, and, when plugged in before the set time, the vehicle preconditions the HVB and the cabin drawing from the L2. This temperature is held for 15 minutes (I think) after the time set, and draws power from the grid during that whole time. It's difficult / impossible to precondition when desired without planning and pre-scheduling with the car, so it encourages setting precondition times that may not be desired on a particular morning.
  
  
• The L2 charge plug does not lock onto the car under load, and the user can remove it by using the physical latch on the plug. and just yanking it out while it is delivering 9+ amps. In other cars, such as our ID.4, the L2 charger is locked by the car and will not release if the system is actively accepting power. In that car, you must press the unlock button on the key FOB for it to stop charging and release. The lock UX is very consistent and you know it will unlock if you press it. As far as I understand, the Mach-E only locks on L3 charging, and does not lock when only L2 is actively delivering power.
  
  
• On my Mach-E, if it is actively preconditioning and holding temperature, pressing the "unlock" button in the middle of the LED status rings DOES NOT stop the preconditioning process and will continue to draw power. There appears to be no easy way to stop preconditioning and get in your car to go without pulling out your phone and encountering lots of app friction to turn off the charger.

I'm just curious if I am missing anything -- otherwise I think I'm just going to stop preconditioning in the morning because there seems to be no easy way to be able to interrupt the preconditioning process without risking an electrical arc or otherwise putting the battery electronics under stress, which I am eager to avoid.

This might be a design flaw Ford should consider fixing through software. They should consider changing charging behavior under L2 to be:

• Charge port locks the L2 charger onto the car when it is actively accepting charge. User must press the "unlock" button next to the J1772 connector in the middle of the LED ring before the mechanism allows for the J1772 to release
  
  
• Pressing the "unlock" button should be a clear signal to the car to ALWAYS stop receiving energy (whether or not Ford has a mechanism to physically lock the connector) so that the L2 or L3 charger can be removed. Under no circumstances should the unlock button be essentially ignored as it appears it is during preconditioning currently

Thoughts from our armchair battery electric engineering department on the forum?

(There's a whole other discussion on why the BECM commands the HVBJB relays sound like they click on when I so much as breathe near my car in the garage. I wonder if this is putting unplanned stress on these parts that Ford may not have considered when it figured out the rating cycles for the parts).

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[JamieGeek]

Pressing the latch on the J1772 connector sends a signal to the car to disconnect charging--there is no arcing at all--the car knows you're unplugging it.

Try this: While it is charging grab the J1772 connector and squeeze the latch without unplugging it. You'll hear your contactors in your EVSE disconnect.

 

[scoopman]

Pressing the latch on the J1772 connector sends a signal to the car to disconnect charging--there is no arcing at all--the car knows you're unplugging it.

Try this: While it is charging grab the J1772 connector and squeeze the latch without unplugging it. You'll hear your contactors in your EVSE disconnect.

If you read my post again, I'm talking specifically about the charging that occurs during a DEPARTURE TIME PRECONDITIONING which it appears exhibits different and undesirable behavior.

 

[JamieGeek]

If you read my post again, I'm talking specifically about the charging that occurs during a DEPARTURE TIME PRECONDITIONING which it appears exhibits different and undesirable behavior.

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.

 

[ZuleMME]

Exactly as mentioned above. Press the release button on your J1772 connector. Wait 1-2 seconds; if it was transferring power (relays closed) you'll hear them open. Done. Disconnect.

 

[SpaceEVDriver]

Whenever we disconnect the Mustang, during preconditioning or not, from our home charging station, we hold down the J1772 plug button for a couple of seconds until our EVSE contactor triggers a disconnect. We can hear the contactors disconnect in both the EVSE and in the car. There's also a safety feature in the J1772 specifications that the proximity pin disconnects first, causing the vehicle and EVSE to both disconnect power.

"The proximity detection pin is connected to a switch in the connector release button. Pressing the release button causes the vehicle to stop drawing current. As the connector is removed, the shorter control pilot pin disconnects first, causing the EVSE to drop power to the plug. This also ensures that the power pins will not be disconnected under load, causing arcs and shortening their life. The ground pin is longer than the other pins, so it breaks last." (Wikipedia)

All of that said, Ford could still have a design flaw in their system that somehow allows something (a discharging capacitor, for example) to weld the contact pins in the HVBJB after the J1772 plug is disconnected. I'm sure Ford electrical engineers are going over the entire design mm by mm trying to fix this as quickly as they can. Obviously there's some kind of design flaw somewhere in the system.

I'll try to remember to hook up my CarScanner while preconditioning and disconnecting sometime soon to track what's actually going on in the signals we have access to.

 

[scoopman]

Exactly as mentioned above. Press the release button on your J1772 connector. Wait 1-2 seconds; if it was transferring power (relays closed) you'll hear them open. Done. Disconnect.

Actually, it appears worse than my original post. Pressing the "unlock" button appears to do NOTHING when you are L2 charging.

See my video experiment taken just now.

 

[scoopman]

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.

Interesting that this is in the spec, but I wonder whether this isn't being followed properly by the car.

 

[scoopman]

Whenever we disconnect the Mustang, during preconditioning or not, from our home charging station, we hold down the J1772 plug button for a couple of seconds until our EVSE contactor triggers a disconnect. We can hear the contactors disconnect in both the EVSE and in the car. There's also a safety feature in the J1772 specifications that the proximity pin disconnects first, causing the vehicle and EVSE to both disconnect power.

"The proximity detection pin is connected to a switch in the connector release button. Pressing the release button causes the vehicle to stop drawing current. As the connector is removed, the shorter control pilot pin disconnects first, causing the EVSE to drop power to the plug. This also ensures that the power pins will not be disconnected under load, causing arcs and shortening their life. The ground pin is longer than the other pins, so it breaks last." (Wikipedia)

All of that said, Ford could still have a design flaw in their system that somehow allows something (a discharging capacitor, for example) to weld the contact pins in the HVBJB after the J1772 plug is disconnected. I'm sure Ford electrical engineers are going over the entire design mm by mm trying to fix this as quickly as they can. Obviously there's some kind of design flaw somewhere in the system.

I'll try to remember to hook up my CarScanner while preconditioning and disconnecting sometime soon to track what's actually going on in the signals we have access to.

Good thinking -- what PIDs should I be looking at?

 

[ZuleMME]

Not that button. Press the release button on the J1772 handle. But don't remove. Listen and you should hear it open.

 

[Blue highway]

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.

 

[Mathington]

Actually, it appears worse than my original post. Pressing the "unlock" button appears to do NOTHING when you are L2 charging.

See my video experiment taken just now.

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

 

[SpaceEVDriver]

Good thinking -- what PIDs should I be looking at?

I'm not sure yet. I'm betting that if there's something going on, you'll see it in several sensors. But I don't really know what to look for yet and need to experiment. And I don't know if there's an actual flaw in my car. So it would be interesting to see if you and I and others have different responses.

I'll dig into this when I have a chance to sit with the car and play with it. I'm sure some others on the forum already know.

My guess is (from this thread) one or several of:

HV Contactor Voltage Positive,HvCVP,0x224805,INT16(A:B)*0.01,0,300,Volts,,,,1
HV Contactor Voltage Negative,HvCVN,0x224806,INT16(A:B)*0.01,0,300,Volts,,,,1
HV Current,HvbA,0x22480b,((signed(A)*256)+B)*0.02,-500,500,amps,7e2,,,1
HVB Voltage,HvbV,0x22480d,INT16(A:B)*0.01,0,500,volts,7e2,,,1
HV Charger Current Requested,ChgOAR,0x224842,INT16(A:B)*0.01,0,500,amps,7e2,,,1
HV Charger Voltage Requested,ChgOVR,0x224844,A*2,0,500,volts,7e2,,,1
HV Charger Output Voltage,ChgOV,0x22484a,INT16(A:B)*0.01,0,500,volts,7e2,,,1
HV Charger Status,ChgSt,0x22484d,LOOKUP(A:A:0='Idle':1='Wait':2='Rdy':3='Chg':4='Done':5='FAULT'),0,5,,7e2,,,1
HV AC Charger Input Voltage,ACInV,0x22485E,INT16(A:B)*0.01,0,300,volts,,,,1
HV AC Charger Input Current,ACInA,0x22485F,A,0,100,amps,,,,1
HV AC Charger Input Frequency,ACInF,0x224860,A*0.5,40,80,Hz,,,,1
HV Charger Pilot Duty Cycle,PilotDC,0x224861,A*0.5,0,100,%,,,,1
HV Charger Pilot Voltage,PilotV,0x2248BC,INT16(A:B)*0.0012,0,15,volts,7e2,,,1

 

[SnBGC]

As many of you know, I just had my High Voltage Battery Junction Box replaced. It failed in some way, perhaps through electrical arcing, and was "stuck" closed, cutting off the HVB from the rest of the car. This was not a fun experience.

Since getting my car back, I've been very aware and thinking of whether I ever remove my L2 charger (as an example) while it is still delivering current -- and I have at times when my car was in the process of preconditioning and holding temperature for a departure time in the morning. I wonder whether removing the L2 charger while it is delivering energy may put undue or unplanned stress on the part that failed.

Unfortunately, Ford seems to be making it easy to have unplugging L2 while under load unavoidable:

• Departure times are the only way to precondition, and, when plugged in before the set time, the vehicle preconditions the HVB and the cabin drawing from the L2. This temperature is held for 15 minutes (I think) after the time set, and draws power from the grid during that whole time. It's difficult / impossible to precondition when desired without planning and pre-scheduling with the car, so it encourages setting precondition times that may not be desired on a particular morning.
  
  
• The L2 charge plug does not lock onto the car under load, and the user can remove it by using the physical latch on the plug. and just yanking it out while it is delivering 9+ amps. In other cars, such as our ID.4, the L2 charger is locked by the car and will not release if the system is actively accepting power. In that car, you must press the unlock button on the key FOB for it to stop charging and release. The lock UX is very consistent and you know it will unlock if you press it. As far as I understand, the Mach-E only locks on L3 charging, and does not lock when only L2 is actively delivering power.
  
  
• On my Mach-E, if it is actively preconditioning and holding temperature, pressing the "unlock" button in the middle of the LED status rings DOES NOT stop the preconditioning process and will continue to draw power. There appears to be no easy way to stop preconditioning and get in your car to go without pulling out your phone and encountering lots of app friction to turn off the charger.

I'm just curious if I am missing anything -- otherwise I think I'm just going to stop preconditioning in the morning because there seems to be no easy way to be able to interrupt the preconditioning process without risking an electrical arc or otherwise putting the battery electronics under stress, which I am eager to avoid.

This might be a design flaw Ford should consider fixing through software. They should consider changing charging behavior under L2 to be:

• Charge port locks the L2 charger onto the car when it is actively accepting charge. User must press the "unlock" button next to the J1772 connector in the middle of the LED ring before the mechanism allows for the J1772 to release
  
  
• Pressing the "unlock" button should be a clear signal to the car to ALWAYS stop receiving energy (whether or not Ford has a mechanism to physically lock the connector) so that the L2 or L3 charger can be removed. Under no circumstances should the unlock button be essentially ignored as it appears it is during preconditioning currently

Thoughts from our armchair battery electric engineering department on the forum?

(There's a whole other discussion on why the BECM commands the HVBJB relays sound like they click on when I so much as breathe near my car in the garage. I wonder if this is putting unplanned stress on these parts that Ford may not have considered when it figured out the rating cycles for the parts).

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....

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