12V Battery FAQ

[Eraser]

@Mach-Lee outstanding write up of the installation process as well as related details. I watched this video for some visual guidance, this was quite helpful as well.

My 12V battery was nearly 4 years old so I decided to swap it out and not tempt fate. The process went smoothly. I pre-charged the battery with an AGM charger so I could hit the ground running without delay. No issues resetting the BMS either.

A day and a half later I took the car out and noticed many features were unavailable/offline. 1-Pedal drive, Auto Hold, lane keeping, Pre-Collision Assist to name a few. After driving for 20 minutes none of those features turned back on. After turning off the car and returning after 15 minutes or so, everything but 1-pedal drive came back online. After my second stop about 30 minutes later, stopping and restarting the car 1-pedal drive came back as well. Since that has never happened before, I can only assume it was related to replacing the 12V battery. I didn't see anyone else mention it (but I didn't read all 20+ pages of the thread), so it might be a one off.

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[Mach-Lee]

@Mach-Lee outstanding write up of the installation process as well as related details. I watched this video for some visual guidance, this was quite helpful as well.

My 12V battery was nearly 4 years old so I decided to swap it out and not tempt fate. The process went smoothly. I pre-charged the battery with an AGM charger so I could hit the ground running without delay. No issues resetting the BMS either.

A day and a half later I took the car out and noticed many features were unavailable/offline. 1-Pedal drive, Auto Hold, lane keeping, Pre-Collision Assist to name a few. After driving for 20 minutes none of those features turned back on. After turning off the car and returning after 15 minutes or so, everything but 1-pedal drive came back online. After my second stop about 30 minutes later, stopping and restarting the car 1-pedal drive came back as well. Since that has never happened before, I can only assume it was related to replacing the 12V battery. I didn't see anyone else mention it (but I didn't read all 20+ pages of the thread), so it might be a one off.

Yes that seems unusual. Couple questions:

• Did you buy the OEM battery?
• How old is it (date code)?
• Did you fully charge it before install?
• Did you see the battery light flash when resetting the BMS?

Make sure you didn't have anything hooked up the negative battery terminal and bypassing the BMS sensor.

May need to do a long charge and reset the BMS again: Thread 'How to Recondition/Service Your 12V Battery' Again, make sure battery charger is hooked up the correct places (use body ground).

If you did everything right, it may be possible you struck out and got a defective new battery.

 

[Eraser]

Yes that seems unusual. Couple questions:

• Did you buy the OEM battery?
• How old is it (date code)?
• Did you fully charge it before install?
• Did you see the battery light flash when resetting the BMS?

Make sure you didn't have anything hooked up the negative battery terminal and bypassing the BMS sensor.

May need to do a long charge and reset the BMS again: Thread 'How to Recondition/Service Your 12V Battery' Again, make sure battery charger is hooked up the correct places (use body ground).

If you did everything right, it may be possible you struck out and got a defective new battery.

Did you buy the OEM battery? Yes, directly from Ford. Part #: BAGMH3
How old is it (date code)? 6/24
Did you fully charge it before install? Yes, prior to installing. Had it on the charger for almost 24 hours, but it finished charging after 2 or 3 hours.
Did you see the battery light flash when resetting the BMS? Yes, surprisingly I nailed it on the first try.

Whatever the issue was seems to be temporary. Zero issues to and from work today.

 

[Fixbear]

@Mach-Lee outstanding write up of the installation process as well as related details. I watched this video for some visual guidance, this was quite helpful as well.

My 12V battery was nearly 4 years old so I decided to swap it out and not tempt fate. The process went smoothly. I pre-charged the battery with an AGM charger so I could hit the ground running without delay. No issues resetting the BMS either.

A day and a half later I took the car out and noticed many features were unavailable/offline. 1-Pedal drive, Auto Hold, lane keeping, Pre-Collision Assist to name a few. After driving for 20 minutes none of those features turned back on. After turning off the car and returning after 15 minutes or so, everything but 1-pedal drive came back online. After my second stop about 30 minutes later, stopping and restarting the car 1-pedal drive came back as well. Since that has never happened before, I can only assume it was related to replacing the 12V battery. I didn't see anyone else mention it (but I didn't read all 20+ pages of the thread), so it might be a one off.

You should not blame it on the battery without further testing or evidence that that is in fact the problem. With software controlled vehicles, a corrupt code line is all it takes to cause a error. Over the 4 years I've had mine, Several OTA's have caused the loss of one pedal and other functions. Several reboots goes back to a saved version. I can't even count how many times we lost one pedal due to the braking safety system and camera.. Pull over, turn it off, and back on. Everything back to normal. Went on from June 24 till OTA in December. Dealing with a computer control vehicle isn't always the most reliable way to do something. When I drove a model "A", tie wire, pliers, crescent wrench and a screwdriver is all I needed to keep it moving. Today you'll need 10 grand of equipment. And software licenses. Do I like the car, YES. Do I like Fords service system, NO. And I worked for a few Ford dealers. It's just way to slow to respond to customers needs. Cars in for weeks or months. Many dealers want to hang on your vehicle for 3 days for a 2 hour job.. Cause they don't know how to manage the floor anymore.. Yea, a software upgrade can blip and cause the tech to go nuts, There by running well over the time manual. But damn, every day?

 

[Anton]

The dealership next to me quoted me ~$175 to swap out the LVB. Waiting on a callback to schedule the mobile service.
I don't think I trust this dealer to fully charge the battery prior to installing it. Is there a way I can check? Or is there a document I can point to which says the battery must be fully charged before swapping it in.

 

[dtbaker61]

you do not have to charge the 12v to 100% before install.

 

[Anton]

you do not have to charge the 12v to 100% before install.

FAQ says otherwise. @Mach-Lee

 

[Anton]

Just passed the 3yr mark on a 2021 job 2. Decided to have the battery replaced before it fails. Cost was $170 incl. parts and labor through Ford Mobile Service. They did the replacement in less than an hour.

Checked the battery level on the old one - 390/380. "It was still good".

 

[Space_Pony]

The dealership next to me quoted me ~$175 to swap out the LVB. Waiting on a callback to schedule the mobile service.
I don't think I trust this dealer to fully charge the battery prior to installing it. Is there a way I can check? Or is there a document I can point to which says the battery must be fully charged before swapping it in.

Fully charge it at home.

 

[Anton]

Fully charge it at home.

With what?

 

[Space_Pony]

With what?

Your 12 volt automotive charger.

 

[GreaseMonkey]

With what?

This science experiment requires drivers with a full SAE certification, not just a drivers license. That should have been the fine print on the sales contract.

 

[Anton]

Your 12 volt automotive charger.

The tech said these things come pre-charged. He already placed it in the vehicle. It's got the 3year warranty now so I don't think I should be messing with it.

 

[dtbaker61]

With what?

turn mme in, disable auto off setting, leave vehicle on overnight. 12v will charge as long as mme is on

 

[Mach-Lee]

you do not have to charge the 12v to 100% before install.

FAQ says otherwise. @Mach-Lee

The battery should be at over 85% (or over 12.75 volts) when it's installed and the BMS is reset. If the battery has been sitting on a shelf for more than a year (check the date code or sticker), it should be charged first. If you're unsure if the battery was fully charged when it was installed, connect a 12-volt (4-amp or larger) battery charger for over 12 hours and then reset the BMS.

Resetting the BMS informs the computer that the battery is at 100% charge and has a 35-amp-hour capacity. However, if the battery is not close to full charge when the BMS is reset, it can cause issues because the BMS will assume the battery has a higher State of Charge (SoC) than it actually does, potentially affecting the accuracy of the capacity algorithm.

If the dealer recently ordered the battery from the central parts warehouse and installed it, it's likely only a couple of months old and in good condition. However, in some cases, a dealer may have a battery in stock for a year or two before anyone needs it. In such situations, it would need to be charged first.

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