This is a true story

[Dude]

When I pushed the start up button the "12 Battery Fault - Service Vehicle Soon" banner caught my attention and quickly disappeared. I proceeded with my morning trip to the park and walk the dog routine. Parked for an hour and then returned to home without incident. The days since the alert Have been uneventful. My vehicle drives well and all systems appear nominal.
Just the facts ma'am.
Monday vehicle was plugged in and charged to 90% SOC
@ 04:05 hrs a message was posted in the Fordpass app to "Plug in to Maintain 12V Battery"
the charge history on the Emporia app displayed "Mon, Sep 25, 2023 at 10:58 AM 1 hour 5minutes 6.29 kWh
and a second entry displayed "Tue, Sep 26, 2023 at 04:05 AM 1 hour 10 minutes 2.53 kWh
After 10:58 AM charge the vehicle remained plugged in and inactive thru the overnight.
Why was the second charge logged when my Mustang was at its charge capacity of 90%?
Why did I receive a warning to plug in the vehicle to maintain its 12volt battery when it was plugged in?
These facts are accurate.
Any hypothesis as to the why this strange event occurred will be considered.

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[RickMachE]

#ShitHappens
#Gremlins

 

[azerik]

Contrary to popular belief, the cloud disconnects quite often.

Some people have been known to get Fordpass alerts days later than they should have. (Tire pressure monitoring seems to be that way some times)

 

[lwilliams0514]

When I pushed the start up button the "12 Battery Fault - Service Vehicle Soon" banner caught my attention and quickly disappeared. I proceeded with my morning trip to the park and walk the dog routine. Parked for an hour and then returned to home without incident. The days since the alert Have been uneventful. My vehicle drives well and all systems appear nominal.
Just the facts ma'am.
Monday vehicle was plugged in and charged to 90% SOC
@ 04:05 hrs a message was posted in the Fordpass app to "Plug in to Maintain 12V Battery"
the charge history on the Emporia app displayed "Mon, Sep 25, 2023 at 10:58 AM 1 hour 5minutes 6.29 kWh
and a second entry displayed "Tue, Sep 26, 2023 at 04:05 AM 1 hour 10 minutes 2.53 kWh
After 10:58 AM charge the vehicle remained plugged in and inactive thru the overnight.
Why was the second charge logged when my Mustang was at its charge capacity of 90%?
Why did I receive a warning to plug in the vehicle to maintain its 12volt battery when it was plugged in?
These facts are accurate.
Any hypothesis as to the why this strange event occurred will be considered.

There still is a 12V old school car battery in the Mach E. This is the error that is letting you know that the battery is getting low on power. Might be time for a trickle charge. I got this error in FordPass. Says to plug in so perhaps the charging will also trickle some charge to that battery.

 

[alexgorod]

I got ODBII to monitor LVB state just based on reading scary stories about it here in the forum, I would definitely do that if I had any error messages from it

It is possible that the errors are fake, or it can be an indication of a real problem of the converter (?) that charges 12V battery while the car is driven or charged, mine is normally above 90% after that.

 

[generaltso]

But, have the names been changed to protect the innocent?

 

[hawkeye3point1]

Why was the second charge logged when my Mustang was at its charge capacity of 90%?
Why did I receive a warning to plug in the vehicle to maintain its 12volt battery when it was plugged in?

FYI, LVB charging/charge maintenance only occurs when the HVB is charging. When HVB charge level is attained, the car goes to sleep and the DC-DC converter that maintains the LVB is shut down.

Your LVB is at a low state of charge because it is not driven enough or you have LVB drain from a device that draws current while the car is sleeping or something is causing the car to wake up and use accessory power excessively.

 

[A-A-Ron]

FYI, LVB charging/charge maintenance only occurs when the HVB is charging. When HVB charge level is attained, the car goes to sleep and the DC-DC converter that maintains the LVB is shut down.

Your LVB is at a low state of charge because it is not driven enough or you have LVB drain from a device that draws current while the car is sleeping or something is causing the car to wake up and use accessory power excessively.

All this, and also a possibility your 12v battery is already going bad. I wouldn’t say it’s common, but you wouldn’t be the first to need a new 12v.

 

[Jppumper]

It could be that your battery is needing to be replaced. If you got the battery warning and then drove, it could be that you put enough of a surface charge to make it seem as though the battery is OK. This time of year, especially, is when batteries go bad. The first cold snap may leave you stranded. Same thing with spring/summer. That being said, a battery can go bad at any time for many reasons.

 

[TheVirtualTim]

Quite a while back ... more than a year ago ... I hadn't used my '21 First Edition for the better part of a week. When I got into the car to start it, I received the "12v battery fault - service vehicle soon" message.

I have contacts at Ford ... so I reached out have them check it. They pulled vehicle logs and what they found was that the module monitoring the 12v noticed the battery was low and needed to charge -- so it initiated a charge (and the battery charged). In other words the car did exactly what it is supposed to do. The mystery is why it issued the "12v battery fault - service vehicle soon" message because according to Ford, the car noticed it needed to start charging and since it was plugged in, it did start charging. My guess is that was a software bug and since that was a while ago it's possibly they issued a fix.

I have also received the message that the 12v is low and I should plug in to maintain it (not an error message ... just a notification).

There are numerous modules that run on 12v power (everything that has to remain powered on when the car is 'off' and the high-voltage battery is disconnected uses the 12v battery). So there's a constant drain on it. The car doesn't gratuitously charge it when you turn on the car ... it only charges it when the module decides a charge is needed. If the car is on it will use the high-voltage battery. IF the car is off BUT the car is plugged in, it will use AC power to charge it.

The car can and will top-off the 12v battery as needed.

There are a number of 12v "cigarette" adapters that provide USB power. I bought one that has a display to report voltage. If the car is 'on' (started) the high-voltage battery is connected and the power on the 12v port will read 15 volts. So you have to test it when the high-voltage battery pack is disconnected (e.g. put the car in 'accessory' mode).

 

[DevSecOps]

FYI, LVB charging/charge maintenance only occurs when the HVB is charging.

Not quite. It also charges while in operation and when needed by the DC DC inverter regardless of being driven or charged so long as the HVB is above 12% SOC.

 

[Dude]

The 04:05 AM log stated that a charge was completed for a longer duration and markedly less kWh than the previous charge? It defies logic. This is blowing my mind.

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