How-To: remove and replace your 12v battery - recommended at 36 months

[Jerrytball]

so..... It might be just possible to get the old battery out WITHOUT pulling the tub.... but definitely would be tight fit. If I had to do it again, I'd try it this way.

I would note that the replacement battery in the video is a different size, without same foot-clamp to secure in place, and different ah, which would throw off the firmware parameters for capacity and charging. I would recommend sticking with 12v-35ah AGM H3 size... which you may have to ask Dealership to order.

I wanted to pull the tub to check out a few other things regardless.

Specifically, I wanted to add beefy cables to 12v connection points for charging/export of 12v. But that' a separate project...

I’ve pulled the negative cables off mine plenty of times and I have that same little set up that she has so I’m guessing I don’t know the 23 is like that I don’t know. Just sharing the video saving some trouble.

Sponsored

 

[dtbaker61]

I understand and I always kind of thinking and this is really going outside my electrical knowledge box lol a big capacitor that holds it burst of power to start the car after it’s running, An inverter that only provides 12 V energy the certain parts, lol I have no idea what I’m talking about. Just ignore that.?

so.... it IS possible to set up EVs without any 12v battery, and just keep the internal dc-dc converter 'on' all the time to supply 12v all the time. However, this has a couple issues:
- reduced life for the dc-dc which would be 'on' all the time, and it's expensive to replace.
- higher draw on the HV battery... the dc-dc is not super efficient at very low loads, and having it on 24/7 would drain energy from the HV battery

 

[nlions]

Thanks for documenting the fun of replacing the 12v battery. I had the same question that
bshaw had and that is why do you need the MME to charge the battery to 100% when a charger will do that without all the steps you went through? Thanks again for the writeup.

 

[Jerrytball]

so.... it IS possible to set up EVs without any 12v battery, and just keep the internal dc-dc converter 'on' all the time to supply 12v all the time. However, this has a couple issues:
- reduced life for the dc-dc which would be 'on' all the time, and it's expensive to replace.
- higher draw on the HV battery... the dc-dc is not super efficient at very low loads, and having it on 24/7 would drain energy from the HV battery

Thank you

 

[mkhuffman]

Thanks for posting this Dan. I think I am going to proactively replace mine this fall.

 

[dtbaker61]

Thanks for posting this Dan. I think I am going to proactively replace mine this fall.

...I thought for sure these batteries would last longer.... and I was willing to test since I knew what to do. But I was unpleasantly surprised by the sudden and complete failure.

the consequences of locking me out of the car could have been MUCH worse if I was in a remote area, especially without cell service as I often am.

I hope that @Ford Motor Company is following this thread, and thinking about a way to prevent lockout in cases of 12v failure.... maybe a setting where you could CHOOSE whether you want doors locked, or UNlocked, or 12v failure.

 

[bshaw]

I hope that @Ford Motor Company is following this thread, and thinking about a way to prevent lockout in cases of 12v failure.... maybe a setting where you could CHOOSE whether you want doors locked, or UNlocked, or 12v failure.

They should have put a key cylinder on the outside of the vehicle somewhere. Both my Lincoln and Chevy that have push button doors have a key cylinder for backup.

 

[dtbaker61]

They should have put a key cylinder on the outside of the vehicle somewhere. Both my Lincoln and Chevy that have push button doors have a key cylinder for backup.

I am all for LESS electronics which would increase reliability, and reduce cost to build and repair.
- mechanical door handles, locks, and 'ignition'
- non-powered seats, cloth or micro-fiber available
- non-powered liftgate (which is available already)
- no proximity sensors, self-drive, lane-center or cameras other than back-up
- smaller 'infotainment' screen
- buttons and levers for HVAC
- I'd even be ok with roll-up windows,

 

[Deleted member 19354]

Zero microfiber towels were harmed in the making of this post.

“Thank you for being the best part of the Ford Family”

 

[ArthurDOB]

Thanks! This is the sort of thing I come here to learn. I appreciate your effort and photos.

 

[Jerrytball]

They should have put a key cylinder on the outside of the vehicle somewhere. Both my Lincoln and Chevy that have push button doors have a key cylinder for backup.

I wonder if there’s any way that you could run that frunck release handle that’s underneath the hood to a spot or even where those charge cables are?

 

[bshaw]

I wonder if there’s any way that you could run that frunck release handle that’s underneath the hood to a spot or even where those charge cables are?

You might be able to, but it would be a security risk as anyone could use it to get into your frunk.

 

[MoonRiver]

It seems that you have the service manual for the job. I wonder what tightening torque is to

I ran my original battery 39 months... tested shortly before 36 months hoping for warranty replacement, but it still tested ok. 'Great' SoH in fact... So I thought I'd charge to 100% and test monthly until it had a problem; thinking that since these little batteries are not cranking a starter they might last a lot longer than 36 mo warranty.

They don't ;(
They can fail suddenly, and without warning....

Possibly leaving you stranded somewhere if you are not prepared. I was lucky mine failed while I was at a jobsite in town and not out at one of my jobs in the booneys. I drove to the site, got out of the car, and the doors locked behind me! PAAK 'unlock' didn't work, Door pillar code bar did not 'light up', so I was stuck. Thank God I had my phone in my pocket and not locked inside the car!

Fortunately, I had several 12v batteries at home (for my solar business), and my wife was able to bring a battery, and a set of jumper cables to get me back on the road...

- used the spare 12v and the front bumper access port connections to pop the hood​

- jumpered the spare battery to the MME connection points, which was easy since I have access holes over the 12v+, 12v-, and HV disconnect. but, I ended up popping off the drivers side beauty cover so I could close the hood over the jumper cables.​

- and was able to start the car and get to my dealership, where they had a h3 35ah battery on the shelf ($211 + $16 core charge)​

I *could* have run with the spare jumpered in if a proper replacement was not available, but I'd recommend to anyone that when you battery hits 36 months, you ought to buy a replacement and carry it with you, along with jumper cables.

So, being a diehard DIYer, I thought I'd document the remove-replacement procedure in case anybody else wants to be prepared to handle it without a tow to a dealership.

=============== DIY remove-replace the 12v ===========

removal procedure starts in service manual page 1999-2001
section 414-01, if you want the factory pictures. The process is:

- remove rear and side 'beauty covers'
- remove Tub - mostly 10mm, and a screwdriver to pop access panels
- remove cross brace - 18mm
- remove/replace battery - 10mm
- reset BCM with dealer 'Scan Tool' , or, follow 'home reset procedure'
Resetting tells the computer you have a brand new battery at 100% heath.


Reset new battery ONLY after charging it to 100%.
The easiest way to charge the new 12v to 100% is:

- turn MME ON
- Turn Vehicle>Settings>auto-off = DISabled
- turn Headlights, A/c, Heat, fan OFF
- .... and leave MME on overnight
- ODB2+Carscanner, or voltmeter, should verify that battery is 100% and
resting at 'float' voltage of 13.2v by morning

THEN, you can 'reset' the BCM to the new 100% capacity by:

- turn MME 'off' once LVB has been charged to 100%
- Press the START button without pressing the brake (ACCESSORY mode)
- Flash the high beams with the stalk 5x
- Press the brake pedal 3x
- Battery icon on instrument cluster should flash 3x to indicate reset
- Turn OFF the car
- Turn OFF Fordpass and Bluetooth if you use PAAK so car-phone are not communicating
- Park the vehicle undisturbed for 6+ hours to allow the BCM to verify the battery SoC and quiescent load


and here are the pictures...

It seems that you have the service manual for the job. I wonder what the tightening torque for the black crossbar mounting nuts is. Does the the manual specify it?

 

[ARK]

Could someone explain how the 12v battery fails on an EV? In an ICE, my experience has been that the 12v just gets worse and worse at holding a charge until you reach the point where even after a few days, you are having to jump start the vehicle.

But on an EV like the MME, if that were happening, shouldn't the 12v just constantly be pinging the high voltage battery for more charge due to inability to hold a charge? How are these batteries having total failures without there first being a period of phantom drain or some notification that the 12v can't reach a charge above say 80%, 60%, 40%, 20%.

 

[Blue highway]

I wonder if / when a failing 12v battery could be detected by the BMS and warn me through the phone app before it is too weak to start the car.

The consequences of failure can be pretty high considering there is no warning.

Sponsored