12v battery fault

[JJR]

Make sure to turn off the 30 minute timer if you decide to do that.

I finally had a chance to test my theory. The 12v battery message appeared. I turned off the timer and let the MME "idle" in the garage for 8 hours. After I turned the MME off a scheduled update was performed without an issue and the HVB dropped 1%.
At least there's an answer to the problem, but I'd still like to see a 12v battery health tile in the Ford Pass app.

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[generaltso]

I finally had a chance to test my theory. The 12v battery message appeared. I turned off the timer and let the MME "idle" in the garage for 8 hours. After I turned the MME off a scheduled update was performed without an issue and the HVB dropped 1%.

What theory was that testing? That the 12V battery is charged when the car is on? Was that in question?

 

[generaltso]

BITE ME!!!

Umm. Wow.

 

[JJR]

It's the typical 12v Fault message. "12v Battery Fault. Service soon." I can tell when the battery is low because the interior lights don't come on. The vehicle turns on just fine.
If charging to the 12v battery stops when the LVB isn't being charged due to reaching its target, that's a problem. Why would you want to stop charging the 12v battery?

On another point; I asked Ford to put the 12v battery status in the Ford Pass App under vehicle/status, on the same page as tire pressure. I was told that a major version release is in the works.

So I did a little non-scientific experiment.
Using a 2022 Premium eAWD Extended Range built 12/21, delivered 4/22, and has 1650 miles.
I started with the LVB at 12.2v. With the MME on the LVB measures 13.6v.
Turning the MME on and disabling the power off timer.
After 6 hours the LVB was 12.5v.
After 12 hours the LVB was 12.55v.
After 24 hours the LVB was 12.7v.
After 24 hours the HVB dropped about 8%.

Draw your own conclusions.
I guess cars are not designed for people who don't drive.

 

[JJR]

So I did a little non-scientific experiment.
Using a 2022 Premium eAWD Extended Range built 12/21, delivered 4/22, and has 1650 miles.
I started with the LVB at 12.2v. With the MME on the LVB measures 13.6v.
Turning the MME on and disabling the power off timer.
After 6 hours the LVB was 12.5v.
After 12 hours the LVB was 12.55v.
After 24 hours the LVB was 12.7v.
After 24 hours the HVB dropped about 8%.

Draw your own conclusions.
I guess cars are not designed for people who don't drive.

Since Ford won't realize that the 12v battery is more important in an EV than in an ICE, I went and installed an Ancel BM300 12v Battery Monitor. It was less than $35 from Amazon. I now have a way of monitoring the SOC of the 12v battery on my phone.
The bad news is that I had to remove the Frunk to access the 12v battery.
The good news is that there's a very good YouTube video on how to remove and reinstall the Frunk.

 

[JJR]

So I did a little non-scientific experiment.
Using a 2022 Premium eAWD Extended Range built 12/21, delivered 4/22, and has 1650 miles.
I started with the LVB at 12.2v. With the MME on the LVB measures 13.6v.
Turning the MME on and disabling the power off timer.
After 6 hours the LVB was 12.5v.
After 12 hours the LVB was 12.55v.
After 24 hours the LVB was 12.7v.
After 24 hours the HVB dropped about 8%.

Draw your own conclusions.
I guess cars are not designed for people who don't drive.

Since I've been having the MME turned on in the garage and turning it off at night, I have had numerous OTAs installed without a glitch.

 

[Rudi Krupsdahl]

I'm thinking that it's the PAAK that's causing the drain. I read that another had the same issue and after the dealers did an inspection, Bluetooth was a possible culprit, since Bluetooth does require power and my phone is almost always within the Bluetooth circle of influence. I deleted the PAAK yesterday since I always carry the fob, it isn't necessary.
I'll take the MME out for a spin to charge up the 12v battery and we'll see if that helps.
I'll update if this is a fix.

Mine doesn't, so I don't think it's the bluetooth connection that's to blame.
Always have it enabled and it doesn't drop percent on the 12v battery.
But you also cannot top up if you have reached your top-up goal on HVB.

 

[dtbaker61]

The HVB is at 90%.

I'm tempted to start the MME and let it sit in the garage "running" all night to see what happens.

A related issue is that PAAK will drain the 12v battery via the Bluetooth connection.

you can reduce drain by turning BT off on your phone when you want your pony to sleep well.

you can leave your MME 'on' , with auto-timeout disabled, turn off headlights manually, and the HV will charge the 12v up to 100% after a day or two, as long as your HV is above 15%. It is good for your 12v to do this a couple times a year.

 

[JJR]

Mine doesn't, so I don't think it's the bluetooth connection that's to blame.
Always have it enabled and it doesn't drop percent on the 12v battery.
But you also cannot top up if you have reached your top-up goal on HVB.

Since I drive my MME very little, like 800 miles per year, I have adjusted my behavior to accommodate the needs of the machine.
I now keep the MME turned on in the garage to keep the LVB charged. I turn it off at night to receive any OTAs.
I have also installed an Ansel BM300 battery monitor that connects to my phone and gives me the LVB SOC.
With the monitor installed there's no guessing if or when the LVB needs charging.

 

[zvez]

Since I drive my MME very little, like 800 miles per year, I have adjusted my behavior to accommodate the needs of the machine.
I now keep the MME turned on in the garage to keep the LVB charged. I turn it off at night to receive any OTAs.
I have also installed an Ansel BM300 battery monitor that connects to my phone and gives me the LVB SOC.
With the monitor installed there's no guessing if or when the LVB needs charging.

why not just get a agm friendly battery tender and keep it plugged in when not driving. That way no leaving the car powered up for hours at a time. You could put a pigtail on the battery, open the frunk and plug in

 

[JJR]

why not just get a agm friendly battery tender and keep it plugged in when not driving. That way no leaving the car powered up for hours at a time. You could put a pigtail on the battery, open the frunk and plug in

Your idea will work, but with the battery monitor I can see when to power-up the MME and use the energy in the HVB that I've already paid for.

 

[Mach-Lee]

why not just get a agm friendly battery tender and keep it plugged in when not driving. That way no leaving the car powered up for hours at a time. You could put a pigtail on the battery, open the frunk and plug in

That's too technical/too much work for a lot of people.

Most people do not need a battery tender unless the vehicle will be sitting for weeks or longer.

If you get 12V drain messages, then you need to find and fix the drain issue rather than trying to put it on a charger. Fix the root cause, not the symptoms.

 

[JJR]

That's too technical/too much work for a lot of people.

Most people do not need a battery tender unless the vehicle will be sitting for weeks or longer.

If you get 12V drain messages, then you need to find and fix the drain issue rather than trying to put it on a charger. Fix the root cause, not the symptoms.

In a lot of cases I don't think there's a drain issue rather just not using the vehicle enough to keep the LVB charged.
Cars and especially EVs were not designed for people who don't drive. That's a joke but it's true.
For me it's as simple as turning the car on and turning the power off timer off when my monitor indicates a low battery. Since I've been doing this I haven't had any problems.
If Ford would help by including an LVB monitor the problem would be solved.

 

[Mach-Lee]

In a lot of cases I don't think there's a drain issue rather just not using the vehicle enough to keep the LVB charged.
Cars and especially EVs were not designed for people who don't drive. That's a joke but it's true.
For me it's as simple as turning the car on and turning the power off timer off when my monitor indicates a low battery. Since I've been doing this I haven't had any problems.
If Ford would help by including an LVB monitor the problem would be solved.

How long does the car need to sit before you get a 12V battery fault message? FYI I can park my car for a whole week without driving it and I don't get any error messages, everything fires up just fine.

You might want to send me your VIN so I can check if your battery is going bad.

 

[lesz]

In a lot of cases I don't think there's a drain issue rather just not using the vehicle enough to keep the LVB charged.
Cars and especially EVs were not designed for people who don't drive. That's a joke but it's true.
For me it's as simple as turning the car on and turning the power off timer off when my monitor indicates a low battery. Since I've been doing this I haven't had any problems.
If Ford would help by including an LVB monitor the problem would be solved.

Like you, I don’t drive frequently or long distances. What works for me is to keep the key in a faraday box and charge with an L1 connection which charges slowly enough to make sure the SOC for the LVB increases before the target SOC for the HVB is reached. I monitor the SOC for the LVB at ‘my account’ on ford.com.

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