Don't wait to replace the 12v battery at 3 years - just do it

[EasyPass]

For consideration:
There is no invisible barrier that definitely compels a 12v battery to be retired at 3 years. My '21 Premium passed 4 yrs in July '25. I occasionally check it's health stats with Car Scanner, and can envision the IPC/Ford App warning of oncoming decay appearing someday when the time has come.

That said any 12v can suddenly give up the ghost anytime. Only difference with an ICE vehicle is that you MIGHT get a warning sign with a slow turnover at startup. Perhaps the IPC/Ford App warning could be its equivalent.

FYI, My wife's Ford PHEV Fusion Energi just recently needed it's 12v replaced after continuous service since fall of 2016! It woke up nearly dead one morning.

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[ghaskins]

In fact, the 12-volt battery powers almost everything other than the drive motors, DC/DC converter, and thermal management.

We are talking accessories, lights, control modules, displays, cabin fans, door locks, air bags, ...

It isn't just used to "start the car".

It's important to note that while there are additional loads on 12v besides starting (e.g. welcome lights, door locks, interior lights, etc), all of those functions should be driving load against the HVB via DC/DC inverter when the car is running, not the 12v battery. If you use accessory-mode, then it would be direct load on the 12v battery, though.

 

[ChrisO]

It's important to note that while there are additional loads on 12v besides starting (e.g. welcome lights, door locks, interior lights, etc), all of those functions should be driving load against the HVB via DC/DC inverter when the car is running, not the 12v battery. If you use accessory-mode, then it would be direct load on the 12v battery, though.

Your correct, my mistake.

 

[shelnian]

I periodically checked my LVB on Car Scanner. After I owned the car 36 months I noticed the LVB wouldn't charge above a SOC of about 68% and that was after I charged it with my battery charger. I asked Mach-Lee about it and he recommended I replace it, so I did. I had no warnings or any other indication the battery was going bad.

 

[Boxman74]

guess I am on borrowed time then. bought aug 21, and 231,000 km. original battery stiill

 

[racker]

For anyone curious, this is the vehicle-reported 12V state of charge before and after replacement on Nov 15. This is a 3.5 year old Mach-E' s original battery. Too bad I don't have more data history, but you can see it drops below 60% once. This car is plugged in and charged every night.

I suppose once I see it approaching "50%" (12.2V?) repeatedly that would be time to replace

 

[dww]

We end of wintering in warmer climates and leaving our '22 in a cold garage for the winter for 6-8 weeks at a time. I was going to change the battery before we left but didn't get around to it.

Do anyone how to charge the 12V while you are gone? I have heard if you turn the car on for 45-60 min at some point the large battery will charge the 12V. It has gone 2 winters this way, but I'm afraid my luck might run out this year without a trickle charger.

 

[racker]

Just buy a cheap NOCO Genius 1 ($24 amazon) if you have a 110V outlet and hook it up. Note the ground (negative) goes to the car frame (note the grounding line)

EDIT oh you left already. IMHO don't do anything

 

[ChrisO]

We end of wintering in warmer climates and leaving our '22 in a cold garage for the winter for 6-8 weeks at a time. I was going to change the battery before we left but didn't get around to it.

Do anyone how to charge the 12V while you are gone? I have heard if you turn the car on for 45-60 min at some point the large battery will charge the 12V. It has gone 2 winters this way, but I'm afraid my luck might run out this year without a trickle charger.

In theory you shouldn't have to do anything because the car will charge the 12V battery when needed from the HVB.

 

[RickMachE]

We end of wintering in warmer climates and leaving our '22 in a cold garage for the winter for 6-8 weeks at a time. I was going to change the battery before we left but didn't get around to it.

Do anyone how to charge the 12V while you are gone? I have heard if you turn the car on for 45-60 min at some point the large battery will charge the 12V. It has gone 2 winters this way, but I'm afraid my luck might run out this year without a trickle charger.

You can't do what you stated. A remote start is 15 min max, and extended for 15 min. Doing 2 remote starts, or one and an extend, then requires a physical start. As you are not there, you have no options.

 

[ipca204]

I find it interesting that there is a thread for the “oldest 12v battery“ as in it some kind of good competition to let it go until you have problems. I personally am planning on changing mine when I get to the three year mark.

heh! That was one I started..still had some action as of last month..

 

[HGxxx]

I have a Oct 22 build that I took delivery in early dec of 22, got Ford pass warning on Nov 23 rd 25, took to dealer failed load test, replaced 12 v under 3 year warranty ( had one more week left of the 36 months).

 

[Sikkun]

That said any 12v can suddenly give up the ghost anytime. Only difference with an ICE vehicle is that you MIGHT get a warning sign with a slow turnover at startup.

Literally every 12v car battery I have had has seemingly randomly died, then I jump it, go to an auto parts store for them to tell me it “test fine”, and then dies again the next day if I stupidly don’t just buy a new one.

The only difference I see with the Mach E is not being able to pop the trunk and do the jump as easily when that happens…which is design I disagree with. But apparently door handles and key holes are not currently in vogue.

 

[Vgkfan]

Got the check 12v battery message on my ford app yesterday at 10am. Mobile service here around 2. $315.

 

[motto]

How did you get this graph?

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