Down for the count :(

[generaltso]

The nugget about not transferring power to the LVB when temp is below 5F (-15C) could be a big deal for people in cold climates. If the car is parked for several days in the cold, you could end up with a dead LVB even with everything functioning as designed.

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[SnBGC]

OK, I was busy last week so missed all this action. A couple things to add:

The "HV to LV Energy Transfer" simply refers to charging the 12V battery when the car is off because it got too low. It is done the same/usual way with the DC/DC converter powered the same/usual way from the HV battery so it's not a special method or different route of charging. It's a special condition triggered by a 12V battery that has gotten too low, which should be rare. When an energy transfer occurs, you get the FordPass message about battery service. They call it an energy transfer because 300 Wh of energy is transferred, which should add back about 70% charge to the 12V battery. The BMS can measure and keep track of energy transferred (volts and amps), which is the basis of the SoC reading it maintains. Some of you noticed the SoC reading changing even though the battery voltage didn't, this is because of temperature or because the BMS is updating the SoC estimate after measuring the open circuit resting voltage after being parked several hours. This is why "idle time" is important for the BMS to update accurately.

The HV to LV transfers are supposed to be limited so as to not cause excess drains to the HV battery or wear and tear on the 12V battery. This is probably the reason for the 48 hour lockout, to eliminate an unnecessary transfer when the battery could just be charged when you drive it the next day. Also, a transfer won't occur when the HV battery is below 15% (to save the HV battery from dying), I think this is why new cars show up with dead 12V batteries. The Mach-E is supposed to be charged if it gets below 25% during transport so that doesn't happen, but most rail yards don't have EV chargers.

When the car is ON, the battery is maintained with normal charging system voltage.

@louibluey I'm not sure about the specifics of them not wanting you to remove the 10mm sensor end of the (-) battery cable, my guess is they are worried about stress to the fragile sensor causing damage. The other end is much more robust. The service manual includes this specific warning:

NOTICE: Do not remove or install the M8 nut on the cable eyelet bolt while the battery monitor sensor is attached to the battery post as this causes damage to the sensor, connector, and possibly the battery post and case.

It was also explained that the DC/DC uses a separate set of auxiliary contractor, and the AC charger (SOBDM) shares the same wires back to the battery. If there was a problem with those contactors (such as sticking), the 12V battery won't be able to charge, even though the car might still be drivable. I've seen some evidence that the 12V battery becomes discharged after getting a red ring charge fault, but I'm not sure if that's because of software or hardware. We could have a situation in software where the car just forgets to turn on the DC/DC converter when it's supposed to, and lets the 12V battery die rather than charging it.

Thanks for jumping in and clarifying. Much appreciated.

These 2 comments in the builder's guide are interesting....

The first was just something that I have always wondered about. Will the LVB get charged when in Transport Mode. Sounds like the answer is "yes" (assuming systems function as intended of course).

The second coment about the message in the car or in the app. Is that the "LVB charging" message or do we think there is a DIFFERENT message when an "energy transfer" takes place? Has anyone posted a photo of what the message looks like inside the car?

 

[SnBGC]

The nugget about not transferring power to the LVB when temp is below 5F (15C) could be a big deal for people in cold climates. If the car is parked for several days in the cold, you could end up with a dead LVB even with everything functioning as designed.

Are you talking about this note?

it is negative 15C, but I looked it up and it does resolve to 5F. Agree.....that could be a little annoying for the vehicles in northern regions.

I wonder how the car knows what temp is for the LVB? Is there a temp sensor on that thing too?

 

[generaltso]

Are you talking about this note?

it is negative 15C, but I looked it up and it does resolve to 5F. Agree.....that could be a little annoying for the vehicles in northern regions.

I wonder how the car knows what temp is for the LVB? Is there a temp sensor on that thing too?

Yeah, thanks, I inadvertently dropped the minus sign for C. I corrected it in my post so I don't confuse anyone. But below 5F is a regular ocurrance in a lot of places.

Interestingly, I haven't driven my car since yesterday and I just randomly got the 12V Battery Fault alert pushed via FordPass. When I look at the widget, it updated the car's info when the alert was pushed (2 minutes ago) and reports 15V. So, as @Mach-Lee has stated, it appears this fault message is generated any time the LVB falls below the threshold for energy transfer to occur. Which is dumb, because if the energy transfer is working as designed, this is not a fault.

 

[hybrid2bev]

Yeah, thanks, I inadvertently dropped the minus sign for C. I corrected it in my post so I don't confuse anyone. But below 5F is a regular ocurrance in a lot of places.

Interestingly, I haven't driven my car since yesterday and I just randomly got the 12V Battery Fault alert pushed via FordPass. When I look at the widget, it updated the car's info when the alert was pushed (2 minutes ago) and reports 15V. So, as @Mach-Lee has stated, it appears this fault message is generated any time the LVB falls below the threshold for energy transfer to occur. Which is dumb, because if the energy transfer is working as designed, this is not a fault.

Makes me wonder if the ‘fault’ message is a bit of code carried over from Ford’s ICE vehicles. (which don’t have a way to supplement the 12v battery energy when the engine is off)

 

[generaltso]

Makes me wonder if the ‘fault’ message is a bit of code carried over from Ford’s ICE vehicles. (which don’t have a way to supplement the 12v battery energy when the engine is off)

Could be. If they changed the message to something like "12V Battery is Charging", it would make a lot more sense. I remember early on people reported seeing a message in FordPass saying something like that, but I haven't seen any reports of that lately.

The way it is now, a lot of cars are getting "12V Battery Fault - Service Soon", and the dealer just says there are no DTCs and the battery tests fine. Seems like Ford would want to work this out. I can't imagine they want people to continue scheduling service for what appears to be normal operation.

 

[SnBGC]

Yeah, thanks, I inadvertently dropped the minus sign for C. I corrected it in my post so I don't confuse anyone. But below 5F is a regular ocurrance in a lot of places.

Interestingly, I haven't driven my car since yesterday and I just randomly got the 12V Battery Fault alert pushed via FordPass. When I look at the widget, it updated the car's info when the alert was pushed (2 minutes ago) and reports 15V. So, as @Mach-Lee has stated, it appears this fault message is generated any time the LVB falls below the threshold for energy transfer to occur. Which is dumb, because if the energy transfer is working as designed, this is not a fault.

Was your vehicle on plug when this message was sent?
I looked through the document to see if the Energy Transfer occurs while on plug but I didn't find any mention of it. Seems like that feature would only be necessary while parked off plug?

As far as I know, I haven't received the 12v fault notice yet. Back in June, I did see a 12v charging notice but it looks like just a courtesy notice and not a fault of any kind. Seems like if the vehicle is plugged in and the LVB SOC drops to a certain level then the vehicle will charge it back up in a normal fashion (vs the Energy Transfer method).

Does this sound about right?

 

[generaltso]

Was your vehicle on plug when this message was sent?
I looked through the document to see if the Energy Transfer occurs while on plug but I didn't find any mention of it. Seems like that feature would only be necessary while parked off plug?

No, it was not plugged in. I don't usually leave the car plugged in when it's home in the garage because I get free charging at work. From what I've measured, the DC/DC converter appears to be active quite often when plugged into L2, so it makes sense that folks that leave their cars plugged in all the time would never see the 12V battery fault.

 

[SnBGC]

No, it was not plugged in. I don't usually leave the car plugged in when it's home in the garage because I get free charging at work. From what I've measured, the DC/DC converter appears to be active quite often when plugged into L2, so it makes sense that folks that leave their cars plugged in all the time would never see the 12V battery fault.

Thanks. Good info. As far as you remember, have all the 12V fault messages occurred when cars are parked off plug?

 

[generaltso]

Thanks. Good info. As far as you remember, have all the 12V fault messages occurred when cars are parked off plug?

Yup, every time.

 

[hybrid2bev]

Thanks. Good info. As far as you remember, have all the 12V fault messages occurred when cars are parked off plug?

Not quite. I got the message while plugged in, but it was not within the charging schedule so the EVSE will not supply power. (schedule is set in the car and on ChargePoint app)

 

[SnBGC]

Not quite. I got the message while plugged in, but it was not within the charging schedule so the EVSE will not supply power. (schedule is set in the car and on ChargePoint app)

Good info. So the 12v fault message has only appeared when vehicles are not plugged into an active plug. My car spends more time on plug than off so it makes sense that I have yet to see that message.

 

[kindofblue]

No, it was not plugged in. I don't usually leave the car plugged in when it's home in the garage because I get free charging at work. From what I've measured, the DC/DC converter appears to be active quite often when plugged into L2, so it makes sense that folks that leave their cars plugged in all the time would never see the 12V battery fault.

Interesting. I'm following this having ordered a Premium AWD and Tesla recommends leaving their cars plugged in overnight when at home.

 

[generaltso]

Interesting. I'm following this having ordered a Premium AWD and Tesla recommends leaving their cars plugged in overnight when at home.

Ford recommends that too when it’s cold. But I don’t.

 

[dixiekidd88]

@dixiekidd88 @Astraea , did you send the photo of my dealership technician notes to your dealer? My car is also a Job1, delivered 2/17/2021. Changing the High Voltage Regulator seems to have fixed it for me. Been driving the car for almost a month now with no repeat issues. These issues happened in 50-60°F weather in NorCal.

@dixiekidd88 if you're in NorCal, consider talking to or bringing your car to Frontier Ford. Mine was the second car they did this fix for, so at this point, it seems like they know what they're doing.

https://www.macheforum.com/site/threads/our-ongoing-nightmare.12075/post-308916

UPDATE:

Ford was able to assist the techs working on ours to determine the High-voltage fuse box and battery energy control module needing replacement. No eta. on dates of when parts will be in and when it will be fixed. This Friday will be 4 full weeks since the breakdown.

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