12V Battery FAQ

[kodiakng]

@Administrator, can this be pinned/stickied? seeing lots of new questions about 12v battery maintenance that this answers.

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[Jayc]

Someone who can answer if this charger would work for the Mach e battery ??

 

[Mach-Lee]

Someone who can answer if this charger would work for the Mach e battery ??

Yes, make sure it’s in AGM mode.

 

[zvez]

@Administrator, can this be pinned/stickied? seeing lots of new questions about 12v battery maintenance that this answers.

yep hands down the best thread on this forum. I learned a ton from it.

 

[Jayc]

Yes, make sure it’s in AGM mode.

Thx Mache-Lee?

 

[dtbaker61]

How often does the 12V battery need to get replaced?

Every 2-6 years depending on your climate and usage level. Heat kills batteries, so the hotter the climate, the shorter it will last. If you live in the southern US, 2-4 years is typical. If you live in the northern US or Canada, 4-6 years is typical. It also depends on usage. FYI if you have a dashcam that drains the 12V battery, your battery will wear out approximately 2x faster than normal (it might only last a year or two with a dashcam).

Is my 12V battery going bad?

If you get warnings in FordPass about your 12V battery, the vehicle frequently enters deep-sleep mode in FordPass, you have a lot of difficulty getting OTAs to install, or notice other odd symptoms, it is possible the 12V battery is going bad. Have the battery tested with a digital battery analyzer by your dealer or other professional and replace as necessary. Also consider reconditioning the 12V battery per my topic to restore some lost capacity.

@Mach-Lee , What do you think is the best indicator that it is time to actually replace the 12v battery ?

Since it doesn't need much capacity and doesn't face any high current loads, and *should* be re-charged automatically from HV when needed... It's hard to tell when it really is time to replace the 12v battery until it gets SO bad that odd symptoms start showing up?

I'm wondering if there is any way to tell when the 12v starts to call for re-charge on a nightly basis, or some other indicator, would be the most effective way to tell when it's time to order a new battery....[/QUOTE]

 

[Zaptrax]

Well, I've read the original post and every reply and I'm still not sure of one thing. I'm going away for 10 weeks and storing my '23 Mach-E in the basement of my LA building's garage. Car will be charged to 50%. I plan to turn off Phone-As-Key, Ford Pass, and have no webcams or other accessories attached. No key fobs will be anywhere near the car and I will disable Welcome Lighting. Do I have to disconnect the neg terminal of the 12v, or can I just lock the car and come back in 10 weeks and have a reasonable expectation that the car will start?

 

[Mach-Lee]

Well, I've read the original post and every reply and I'm still not sure of one thing. I'm going away for 10 weeks and storing my '23 Mach-E in the basement of my LA building's garage. Car will be charged to 50%. I plan to turn off Phone-As-Key, Ford Pass, and have no webcams or other accessories attached. No key fobs will be anywhere near the car and I will disable Welcome Lighting. Do I have to disconnect the neg terminal of the 12v, or can I just lock the car and come back in 10 weeks and have a reasonable expectation that the car will start?

Ford says you should disconnect the 12V battery in the owner’s manual, but I think you’re okay to leave it as long as you don’t have any drain problems. I would arrive prepared with a jump pack upon return just in case the 12V battery died. Watch the jump start videos beforehand.

 

[Zaptrax]

Thanks, I did read the manual but I assumed Ford did not want to get into nuances, like "if you are storing the car at less than X degrees or more than Y degrees", etc etc so disconnecting the terminal was a good evergreen answer. Too bad the designers didn't get the memo and allow for easier access to the negative battery terminal. At least they put the little access port in the bumper to jump the frunk.

Do you have a recommendation for a little portable 12v AGM-compatible charger?

 

[waternut13134]

So I dont do a ton of far driving as everything from my work and places I shop are all within 15 miles from my house. If I do recommendation of leaving my car on for 2 hours a week with no AC to charge the 12V battery can I have my car actually plugged into my phase 2 charger so its not depleteing the HVB?

 

[Jerrytball]

I know I’m probably gonna answer my own question but here it goes. If you plug something in to the cigarette lighter to charge externally, for example, portable battery pack, without the car running, is it using the 12 V battery, but if I start the vehicle does it affect the 12 V battery and get charged through the HVB? Probably both answers are yes, and yes.

 

[mkhuffman]

So I dont do a ton of far driving as everything from my work and places I shop are all within 15 miles from my house. If I do recommendation of leaving my car on for 2 hours a week with no AC to charge the 12V battery can I have my car actually plugged into my phase 2 charger so its not depleteing the HVB?

It seems that the 12V battery is only charged via the L2 EVSE while the car is charging. Once charging stops, I don't believe it uses the L2 connection. However, to be sure I would need to leave it plugged in fully charged and monitor the LVB. I think I am going to do that and I will let you know what I observe.

 

[mkhuffman]

I know I’m probably gonna answer my own question but here it goes. If you plug something in to the cigarette lighter to charge externally, for example, portable battery pack, without the car running, is it using the 12 V battery, but if I start the vehicle does it affect the 12 V battery and get charged through the HVB? Probably both answers are yes, and yes.

I think the cigarette lighter outlet turns off when the car is off for a few minutes. Have you confirmed it stays on? In that case, that charging method won't work. But maybe I am remembering incorrectly.

 

[Jerrytball]

I think the cigarette lighter outlet turns off when the car is off for a few minutes. Have you confirmed it stays on? In that case, that charging method won't work. But maybe I am remembering incorrectly.

I’ve never plugged in anything on this car but I know on my regular Mustang I used to have an LED charger, well there was a charger that had an LED light on it and I would go out and it would be 15 minutes, so I’m assuming you’d have to leave the car running to charge something out of that 12 V? And if that’s the case, if the car was running would be draining the small battery or the bigger battery ?

 

[DRCal68]

We are planning to leave our car unplugged in our garage while away for 3 weeks. No phones or keys will be near it. I was thinking of leaving the hood unlatched so I can use my 12V jump pack more easily if necessary on return. I noticed the frunk interior light times out after some period so I will unlatch the hood before charging the HV battery from 40% to 50% the night before.

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