Plug in to maintain 12V Battery

[Silver Pony]

I have 2022 Premium AWD Mache with 43,000 miles and it is approaching three years in age. I keep getting error messages on my screen and my phone that say "Plug in to Maintain 12 V Battery" even though the car was plugged in and charging overnight. It seems to be worse on colder nights with temps below freezing. It seems that when I plug in to charge the main battery, the 12V battery does not charge. I try to always make sure to set the head lamps from Auto to off when I leave the car as I heard leaving the lights on Auto overnight may drain the 12V battery. It seems like something is draining the 12V battery when the car is off. I drive the car at least 5 to 20 miles just about every day.

I did a google search and found this article. Does anyone know if there is a scan or software update that will correct this issue so the 12v Battery will charge overnight? Should I replace the 12V battery after 3 years? The car is no longer covered by the 3 year bumber to bumber warrenty, so I am hesitant to bring it to the dealer until I have a better idea of what needs to be done to correct this issue.

Thanks. I appreciate any advice you can share, especially from someone from Ford.

Eric

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[emichnov]

The 12 V battery only charges when you are driving or while plugged in AND charging the HVB - not when plugged in and NOT charging the HVB. You don't have enough miles each day to maintain the 12 V battery. Simply charge it using a regular 12 volt battery charger over night and you'll be fine. Or, if you still get errors, then yes, maybe your 12 V battery needs replacement.

 

[Snakebitten]

I highly suggest replacing the battery.
First because a dead 12V AGM can be far more than just an inconvenience on the Mach-E.
And second, because you wouldn't be the first person experiencing symptoms of an H3 AGM being near end-of-life at the 3 year mark.

 

[Silver Pony]

Great, thanks. I will have the 12V battery changed.

What about TSB 21-2091. Should I have my local Ford dealer do this or leave it alone. I purchased my car in February 2022.

Thanks,

Eric

.

 

[Snakebitten]

Absolutely get the dealership to update any/all software updates that you can convince them to do for you.

And presenting them with TSB/CSP/etc documentation is certainly one way to get them to at least consider doing updates. (since they can be paid by Ford for doing so)

 

[Tbird]

As a side note, You can give your 12 v battery more time to charge while charging your High voltage battery by reducing the HVB charging amps. I normally charge at 10 to 15 amps on my Charge Point Home charger overnight. This gives my 12 v battery more time charging and provides 20 - 36 kwh (60 - 100 miles).

I also know that if my 12 v battery gets to 45% state of charge the car will automatically charge it back up from the high voltage battery even if it is not plugged in.

 

[JJR]

I have 2022 Premium AWD Mache with 43,000 miles and it is approaching three years in age. I keep getting error messages on my screen and my phone that say "Plug in to Maintain 12 V Battery" even though the car was plugged in and charging overnight. It seems to be worse on colder nights with temps below freezing. It seems that when I plug in to charge the main battery, the 12V battery does not charge. I try to always make sure to set the head lamps from Auto to off when I leave the car as I heard leaving the lights on Auto overnight may drain the 12V battery. It seems like something is draining the 12V battery when the car is off. I drive the car at least 5 to 20 miles just about every day.

I did a google search and found this article. Does anyone know if there is a scan or software update that will correct this issue so the 12v Battery will charge overnight? Should I replace the 12V battery after 3 years? The car is no longer covered by the 3 year bumber to bumber warrenty, so I am hesitant to bring it to the dealer until I have a better idea of what needs to be done to correct this issue.

Thanks. I appreciate any advice you can share, especially from someone from Ford.

Eric

I also have a 2022 Premium. If you park in a garage you can do what I do to charge the LVB.
Every Sunday, or every other Sunday if I forget, I turn the car on and disable the automatic turn off option on the screen under the Vehicle tab.
I let the car idle for 12 hours or so and this keeps the LVB at a level that will stop those messages.
You can also install a battery monitor like the Ancel BM300 and then you will have the ability to see the state of charge of the LVB on your phone.
Since owning my MME I have realized that cars are not designed for people who don’t drive. ?

 

[BayPoodle]

From what I’ve seen here it is probably a good idea to replace your 12v since it is almost at the 3 year mark. However, I get those error messages from time to time (my MME is a year old) and I find resetting the 12v resolves it. Also fixes essentially everything else that goes wrong with the car.

 

[lesz]

The 12 V battery only charges when you are driving or while plugged in AND charging the HVB - not when plugged in and NOT charging the HVB. You don't have enough miles each day to maintain the 12 V battery. Simply charge it using a regular 12 volt battery charger over night and you'll be fine. Or, if you still get errors, then yes, maybe your 12 V battery needs replacement.

when practical, you can also charge at L1. The slower charging rate for the HVB will allow the LVB to charge longer.

 

[PA27]

Same situation, only drive about 20 miles a day and due to near freezing temps, plugged in most nights right now but get low 12v message. I overcome Ford’s inability to charge the 12v by turning the car on while plugged in, all accessories (heat, lights, seats, radio, etc) turned off and leave it on about an hour. only had to do this once last winter and have not had the warning until just last week. Hopefully one and done this year too. Seems ridiculous Ford doesn’t adjust charging software to maintain the 12v battery ?‍

 

[Eagertrader]

My 12V battery died without warning 1 week before the third year.

 

[JJR]

I have 2022 Premium AWD Mache with 43,000 miles and it is approaching three years in age. I keep getting error messages on my screen and my phone that say "Plug in to Maintain 12 V Battery" even though the car was plugged in and charging overnight. It seems to be worse on colder nights with temps below freezing. It seems that when I plug in to charge the main battery, the 12V battery does not charge. I try to always make sure to set the head lamps from Auto to off when I leave the car as I heard leaving the lights on Auto overnight may drain the 12V battery. It seems like something is draining the 12V battery when the car is off. I drive the car at least 5 to 20 miles just about every day.

I did a google search and found this article. Does anyone know if there is a scan or software update that will correct this issue so the 12v Battery will charge overnight? Should I replace the 12V battery after 3 years? The car is no longer covered by the 3 year bumber to bumber warrenty, so I am hesitant to bring it to the dealer until I have a better idea of what needs to be done to correct this issue.

Thanks. I appreciate any advice you can share, especially from someone from Ford.

Eric

Here’s a screenshot of the LVB being charged by the HVB while parked. The app is from an Ancel battery monitor.
Notice the jump to 15v.

 

[Teslaeata]

The 12 V battery only charges when you are driving or while plugged in AND charging the HVB - not when plugged in and NOT charging the HVB. You don't have enough miles each day to maintain the 12 V battery. Simply charge it using a regular 12 volt battery charger over night and you'll be fine. Or, if you still get errors, then yes, maybe your 12 V battery needs replacement.

This is not strictly true.

Whether plugged in, charging, driving or not, so long as HVB is over 15% SoC battery management should charge LVB within 48hrs once its charge drops below to 40% or immediately if LVB drops to 30%.

Current percentages may differ as I think some software updates may have altered them but you get the idea.

If LVB is still throwing up faults then there are system faults which need checking out.

 

[CWP3]

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