Plug in to Maintain 12V Battery

[Mach1E]

So this might be a dumb question, but does doing what the alert asks and plugging in not solve the problem?

Dunno. This car seems weird when it comes to the 12v.

I got this message twice today for the first time ever (took delivery Oct 2021). My LVB was at 12.3v so I charged it to 13.

My HVB was around 90%.

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[vinny2487]

Dunno. This car seems weird when it comes to the 12v.

I got this message twice today for the first time ever (took delivery Oct 2021). My LVB was at 12.3v so I charged it to 13.

My HVB was around 90%.

Had the same thing happen to me as well Monday morning along with the notification on the app. Interesting thing was that I didn't get the notification on the app until later in the evening. Car started up fine but I did get the cheap sounding start up Ford chimes. Drove the car for a little bit and has been fine ever since.

I did have 5.1.1 installed a couple days before this so I wonder if there's a new bug.

 

[Kamuelaflyer]

Had the same thing happen to me as well Monday morning along with the notification on the app. Interesting thing was that I didn't get the notification on the app until later in the evening. Car started up fine but I did get the cheap sounding start up Ford chimes. Drove the car for a little bit and has been fine ever since.

I did have 5.1.1 installed a couple days before this so I wonder if there's a new bug.

I’ve seen that a couple of times in the past. All before 5.1.1 installed. No clue why though.

 

[vinny2487]

I’ve seen that a couple of times in the past. All before 5.1.1 installed. No clue why though.

Oh yeah I've had the "System off to save battery" screen multiple times before 5.1.1, and it's usually when I don't use the car for multiple days. But this was the first time I've gotten an alert on FordPass about it. No prompts of "Service now" on the instrument panel though when starting up the car.

 

[Mach-Lee]

Does this apply even if you don’t turn on the car? Is there any technical or otherwise valid reason to not have the car maintain itself while plugged in? Its clearly aware of its own low battery and has the capability to charge it.

I ask because my previous MME had to be jumped via roadside assistance while at my house because the 12V drained while it was plugged in overnight.

It should automatically recharge itself when it gets down to 40-50% as long as the high voltage battery isn't low (>15%). However for whatever reason(s) that doesn't always work. There was some bad software in the initial Mach-E's, things are better now.

So this might be a dumb question, but does doing what the alert asks and plugging in not solve the problem?

Well, we don't know. I don't think you should even be seeing that message unless your high voltage battery is down to below 15%. I think it's being generated in error or with the wrong entry conditions. Plugging in will not solve the problem unless your car needs to charge for an hour or more. If the car is already charged and you plug in, it won't do anything for the 12V battery.

 

[Auto Motive]

These “Plug in to maintain the 12v” messages had essentially stopped a while ago after software updates and a visit to the dealer. Ever since the 6.1 software update they are back with a vengeance. Anyone else seeing this correlation?

I had the 12v fault two months ago that came on several times a week. Dealer software update fixed it until yesterday. I will hook up my trickle charger to see if this solves it. Our new model y has a 16v lithium battery wired in.

 

[Frebster]

So this might be a dumb question, but does doing what the alert asks and plugging in not solve the problem?

Hopefully it will solve the problem.

 

[Mach1E]

Had the same thing happen to me as well Monday morning along with the notification on the app. Interesting thing was that I didn't get the notification on the app until later in the evening. Car started up fine but I did get the cheap sounding start up Ford chimes. Drove the car for a little bit and has been fine ever since.

I did have 5.1.1 installed a couple days before this so I wonder if there's a new bug.

Same with the Ford chimes.

But I haven’t had a update in a while. My last one was the update that “fixed presets.”

 

[fpasta]

I get the system off to save battery message with the cheap front sensor chimes always after I hand wash the car. I power off car open door turn Bluetooth off (SOP on a normal day when parked in garage) close door and wash.

I'll try turning off motion sensors before I wash?

 

[Indy Mike]

These “Plug in to maintain the 12v” messages had essentially stopped a while ago after software updates and a visit to the dealer. Ever since the 6.1 software update they are back with a vengeance. Anyone else seeing this correlation?

Yes

 

[dtbaker61]

Does this apply even if you don’t turn on the car? Is there any technical or otherwise valid reason to not have the car maintain itself while plugged in? Its clearly aware of its own low battery and has the capability to charge it.

I ask because my previous MME had to be jumped via roadside assistance while at my house because the 12V drained while it was plugged in overnight.

something is wrong with car if it is not self-maintaining the 12v.... as long as HV is above 15%. You should not need to be plugged in.

 

[Just Lurking]

Dunno. This car seems weird when it comes to the 12v.

I got this message twice today for the first time ever (took delivery Oct 2021). My LVB was at 12.3v so I charged it to 13.

My HVB was around 90%.

That is odd, though based on the other commenters apparently not uncommon or at least not unheard of.

Plugging in will not solve the problem unless your car needs to charge for an hour or more. If the car is already charged and you plug in, it won't do anything for the 12V battery.

So that's interesting; the 12V only charges while the HVB is also charging? Seems like an odd decision. If true, then people who drive few miles and charge occasionally or even rarely with an L2 charger might be most at risk. I don't drive many miles but mostly charge with an L1 charger, so I top up at least 3-4 times per week and usually for several hours at a time.

My understanding is that 12V lead-acid batteries do best when maintained at or close to 100% charge at all times (unlike lithium-ion batteries which do best around 50% charge). I can understand Ford deciding not to sacrifice HVB charge to keep the 12V charged to 100% at all times, and I can even understand not sacrificing charge speed to top up the 12V completely while also charging the HVB (though not sure how big an impact on HVB charge speed this would have). But plugged in and not charging the HVB seems like the perfect time to top up the 12v battery!

 

[Mach-Lee]

So that's interesting; the 12V only charges while the HVB is also charging? Seems like an odd decision. If true, then people who drive few miles and charge occasionally or even rarely with an L2 charger might be most at risk.

Yes and yes. Apparently a lot of retired and WFH people own this car, and don't even drive 20 miles per week, so in those use cases the 12V will become low from lack of driving and charging hours.

It is best to keep the 12V around 90% charged, charging to 100% all the time can put extra stress on the plates and cause accelerated grid corrosion. Cycling lead acid batteries also contributes to their demise. With normal use the 12V will typically be around 70-90% SoC. Things could be programmed a little bit better to start the recharge process sooner before a load shed occurs ("System off to save battery"), that way the customer doesn't notice.

 

[dww]

so if I leave my MME for 7 weeks, should I leave it plugged in?

 

[SaintPaulMustangMach-E_GT]

I've got the same 12v issue, but it's only shown up once, just last week, right after a software update. Given that, it's likely it's a bug. Ford, are you listening?
I drive a minimum of 40 miles per day and charge almost every night.
The day that I got the message was after two days (very rare) of not charging.
But unlike most of you, I'm in a super cold weather area (MN).
Batteries often start acting up and have a temp change; we just dropped from the high 80s (F) to the low 50s (F) over a 40(F) change in two days.
So, given two days since the last charge and the temp change and software update would this most likely be a:

1. Bad Software Update
2. Bad 12v battery

Does anyone know the warranty for the 12v battery?
I assume it's covered for this May 2022 delivered Mach-E.

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