Replace 12v battery at 36 months - no question's asked

[devmach-e]

I know you know this, … but, …. It will keep working fine until it doesn’t work at all - usually at 6 in the morning when you need to be somewhere. It, hey, life on the edge can be exciting …

Ford has put systems in place to try to give more advanced warning that the battery is going to fail. Batteries can fail at less than 1-year of life, too. I monitor the health of the battery via a variety of methods and all indicate that the battery is being well maintained by the car’s systems.

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[matwlev]

Where did the advice to replace at 36 months originate? My dealers tells me every time that the battery is fine and there’s no need to replace. I got my 21 used, but they said the battery looks original.

 

[wdk1947]

Went to far and fell in the 12 VDC failure trap. am posting to warn and help you avoid this issue. DO DEMAND or replace yourself the battery at the 36 month mark. I was lucky and blessed by a great dealer that had mobile service. Went past the 36 month and got caught at 41 months. Fortunately i was at home my Dealer was awesome and were able to support same day mobile service. Could have been allot worse. DO NO MAKE THE SAME MISTAKE! Change your 12 VDC battery at 36 months on the normal maintenance appointment. tell them to change it without a test. As they say JUST DO IT.

UPDATE 7/11 More info: I had the 12V warning at 36 months and asked the Dealer to replace it at the 40K service. They said there was a software change and the warning was inaccurate also reported the battery tested fine (Again UNTIL IT FAILS) I did get another warning the day before it failed.

ALSO shout out to to the reply noting the door entry button and other functions like recognizing the phone as a key close to the car were not functioning well prior to the failure and just figured it was something to do with an update. All that was corrected with the new battery as well. To me this is strange but also true

Just had my 23 in for yearly inspection car built April of 23 had the battery changed because of this forum no need to look for issues. Car only has 20,000 plus miles

 

[Maquis]

Where did the advice to replace at 36 months originate?

It’s a 36 month battery…

 

[HuntingPudel]

The problem with this is when your battery is "full" at 80% capacity or higher, it doesn't always test accurately. I had mine test "OK" twice after showing signs of issue before it failed a day later. There's damage that doesn't appear when it's been charged recently.
<SNIP>

Additionally, most techs don’t realize that the car keeps the inverter active for several minutes (up to 12) after the car has “turned off.” So at that point they are testing a battery that is attached to a running charger.

 

[AZBill]

Damn, I'm at 77K miles and 50 months. Guess I missed the deadline by quite sometime. Battery continues to work fine...

Mine last 52 months in the Arizona heat. I got a message in the Ford app that it needed replaced, did it myself.

 

[allenj444]

Okay here’s my question. My ‘25 was manufactured in Feb ‘25 but sat on the lot till I purchased it on Sep 6. Should I account for those 7 months, or from the time I purchased it? The car had just under 200 miles on the ODO (from test drives and driving it from another dealer in GA.) when I bought it.

I’m inclined to think I should start the 36 mo countdown from Feb ‘25. Thoughts?

 

[HuntingPudel]

Okay here’s my question. My ‘25 was manufactured in Feb ‘25 but sat on the lot till I purchased it on Sep 6. Should I account for those 7 months, or from the time I purchased it? The car had just under 200 miles on the ODO (from test drives and driving it from another dealer in GA.) when I bought it.

I’m inclined to think I should start the 36 mo countdown from Feb ‘25. Thoughts?

Not only should you count the months the car was completed before you got the car, you should count the months before the battery went into the car. It’s battery age, not car age.

 

[matwlev]

It’s a 36 month battery…

I mean, I see that it has a 36 month warranty. The big battery has an 8 year warranty but hopefully it’s not an “8 year battery”-!

 

[Maquis]

I mean, I see that it has a 36 month warranty. The big battery has an 8 year warranty but hopefully it’s not an “8 year battery”-!

Not a fair comparison.

 

[RickMachE]

I bought my '23 in early '24 and am just now coming up on the end of my warranty early next year. I'm hoping the battery dies soon so I can get it replaced under warranty, but if not, my plan is to replace it immediately after the base warranty ends.

Most dealers will perform a battery test for free. Do it at 35.5 months. Got a new battery in the Lightning, but not the Mach-E.

 

[allenj444]

Not only should you count the months the car was completed before you got the car, you should count the months before the battery went into the car. It’s battery age, not car age.

Ahh good point! I’m on a 1200 mile vacation now. When I get home I will definitely check the date of manufacture

 

[matwlev]

Not a fair comparison.

Why not? I’m not comparing battery to battery, just the logic of “if something has a warranty for x number of years, that means it should be replaced at x number of years.” Why does that apply to this one battery? I’m not disagreeing with the suggestion to replace at 36 months, just asking why that’s the magic number (and maybe why there is a magic number at all?). Seems like the guidance should be a bit more nuanced based on situation,
battery testing, and now the warning in the app.

 

[4sallypat]

It’s a 36 month battery…

Is it worth getting the larger H5 battery and shoe horning it in ???

 

[jdrrnn]

Okay here’s my question. My ‘25 was manufactured in Feb ‘25 but sat on the lot till I purchased it on Sep 6. Should I account for those 7 months, or from the time I purchased it? The car had just under 200 miles on the ODO (from test drives and driving it from another dealer in GA.) when I bought it.

I’m inclined to think I should start the 36 mo countdown from Feb ‘25. Thoughts?

Mine had a build date of November 2023 and sat on the lot until May 2024. I bought it brand new but the dealer wasn’t maintaining it I’m sure. Long story short, I had to replace it July 2025 because it was failing under load. Not sure if it was killing the battery just sitting on the lot or I got a defective one or what, but that was my experience.

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