How to keep a charge on the 12V?

[Louie N]

Hello All,

The Mustang Mach E is my first EV and I and hoping to learn more about the 12V battery after my recent experience.

knowns...
The 12V charges while driving through a DC to DC converter
if I am using preconditioning the car will "warm up" and also ensure the 12V is fully charged. I believe the DC to DC converter is engaged during preconditioning.

unknown...
Does the 12V get charged when the vehicle is charging?
Is the 12V being "trickle" charged whenever the car is plugged in even if it not actively charging?
Is the preconditioning the most important thing I can do to ensure a good charge on the 12V?

Just trying to learn

Thank you for any information.

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[Kabish]

I don't know the definitive answer to those questions, but I have an idea of what the answers are from reading the forum. I don't want to spread misinformation, so I'll just keep an eye on this post to see if I'm right or not

 

[Mach-Lee]

unknown...
Does the 12V get charged when the vehicle is charging?
Is the 12V being "trickle" charged whenever the car is plugged in even if it not actively charging?
Is the preconditioning the most important thing I can do to ensure a good charge on the 12V?

Yes, 12V is maintained while charging.

If the car is plugged in L1/L2 not charging the DC/DC module goes to sleep, but will wake up periodically and charge the battery if it gets low. Same if the car is sitting unplugged. However if you are using a very large draw accessory like an inverter you should leave the car ON since it might draw too much power before the DC/DC wakes up.

You shouldn't have to think about doing anything special for the 12V battery, it should take care of itself. There were some bugs in the early software that caused issues, but those are resolved now. If you do encounter 12V battery issues, you should take your car into the dealer and have everything updated as a first step.

 

[Kabish]

Same if the car is sitting unplugged

I did not know the HVB would charge the LVB when its just sitting parking, kind of a good thing to know.

 

[QuRace]

Yes, 12V is maintained while charging.

If the car is plugged in L1/L2 not charging the DC/DC module goes to sleep, but will wake up periodically and charge the battery if it gets low. Same if the car is sitting unplugged. However if you are using a very large draw accessory like an inverter you should leave the car ON since it might draw too much power before the DC/DC wakes up.

...

Not questioning your answer at all, but: Where do you get this kind of information (in writing...)?

I don't remember reading anything that specific in the user manual, so: Do you have access to some internal company info? Or what else is it? Reverse engineered the system over OBD?


.

 

[RickMachE]

My Fusion Energi 12v battery charged after the main battery completed charging. This should be no different.

 

[benk016]

There is a bug with some cars that if you plug in, and have the car in accessory mode, the 12v system won't charge and will drain the battery within 45 minutes and you'll start getting all the alerts pop up as the voltage drops.

My dealer updated a few modules and this no longer happens, and the 12v system is being charged now as expected while plugged in to L2.

 

[benk016]

There is a bug with some cars that if you plug in, and have the car in accessory mode, the 12v system won't charge and will drain the battery within 45 minutes and you'll start getting all the alerts pop up as the voltage drops.

My dealer updated a few modules and this no longer happens, and the 12v system is being charged now as expected while plugged in to L2.

 

[TRP]

On occasion when a scheduled charge starts at home the FP app will have a banner that says "Charging 12v Battery" before the HVB starts to charge. It doesn't happen every time but often enough for me to be confident that it is monitoring the 12v battery and charging when needed

 

[Louie N]

Hello,

Thank for the replies. The confusion around this is why I asked the question. The 12V being depleted happen to me and I want to ensure it does not happen again. Maybe the SW fix is all I needed.

First Post - Broken Heart - Car Would not Start - Solved (Update 9/24/21) | Ford Mustang Mach-E Forum - MachEforum.com

Also just exploring the new technology.

Thanks

 

[breeves002]

Not questioning your answer at all, but: Where do you get this kind of information (in writing...)?

I don't remember reading anything that specific in the user manual, so: Do you have access to some internal company info? Or what else is it? Reverse engineered the system over OBD?

The information comes from people on this forum figuring it out over the past year. Observation of how systems function along with technical info from the workshop manual.

 

[Mach-Lee]

Not questioning your answer at all, but: Where do you get this kind of information (in writing...)?

I don't remember reading anything that specific in the user manual, so: Do you have access to some internal company info? Or what else is it? Reverse engineered the system over OBD?

Service manual.

 

[ChasingCoral]

Not questioning your answer at all, but: Where do you get this kind of information (in writing...)?

I don't remember reading anything that specific in the user manual, so: Do you have access to some internal company info? Or what else is it? Reverse engineered the system over OBD?

Lots of threads discussed this several months ago.

 

[HuntingPudel]

Hello,

Thank for the replies. The confusion around this is why I asked the question. The 12V being depleted happen to me and I want to ensure it does not happen again. Maybe the SW fix is all I needed.

First Post - Broken Heart - Car Would not Start - Solved (Update 9/24/21) | Ford Mustang Mach-E Forum - MachEforum.com

Also just exploring the new technology.

Thanks

Did your dealer apply the software update to correct this issue when your MME was being serviced for the depleted 12V battery? If they did not, you should make sure that they do.

 

[Louie N]

HuntingPudel,

The dealer did apply the TBS 21-12091 SW patch. No problems so far after 5 days. But you know makes you nervous.

Thanks

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