To Plug in or not when away for a couple of weeks?

[Adventureboy]

Guys--following what we've also done with our two ICE cars, we bought a third Battery Tender, Jr and a matching extension chord with cigarette lighter plug at the other end. Plan to plug this into the cigarette lighter 12v in the luggage area of our 2024 MME GT to keep the 12v topped off line we do in the other two cars. A preliminary test with one of the other setups seemed to indicate power was active to the 12v with this method. (All purchased from Amazon.)

Access is more convenient than taking apart stuff inside frunk.

Thoughts?

I am not convinced this will work. I expect the MME will shut down the rear outlet after 30 minutes or so and disconnect the jumper.

The car will manage the 12v provided the HVB is 50-60% and you have gotten OTA updates in the last year or so. I'd only worry about it if leaving it for more than 30 days or in the dead of winter.

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[HuntingPudel]

Guys--following what we've also done with our two ICE cars, we bought a third Battery Tender, Jr and a matching extension chord with cigarette lighter plug at the other end. Plan to plug this into the cigarette lighter 12v in the luggage area of our 2024 MME GT to keep the 12v topped off line we do in the other two cars. A preliminary test with one of the other setups seemed to indicate power was active to the 12v with this method. (All purchased from Amazon.)

Access is more convenient than taking apart stuff inside frunk.

Thoughts?

The circuit that the cigar lighter socket is connected to goes dead a short while after the car is shut off. So a cigar lighter plug won’t work.

 

[Bad Dolphin]

The circuit that the cigar lighter socket is connected to goes dead a short while after the car is shut off. So a cigar lighter plug won’t work.

Thanks to both of you. How about if I leave the car on and plugged into Ford charger with climate control and auto shutdown turned off?

 

[RickMachE]

Thanks to both of you. How about if I leave the car on and plugged into Ford charger with climate control and auto shutdown turned off?

You're going to leave the vehicle running, for days on end, to keep the 12v charged? Umm....

 

[thenew3]

Thanks to both of you. How about if I leave the car on and plugged into Ford charger with climate control and auto shutdown turned off?

How long are you going to be gone? I left mine unplugged for 29 days and had no issues. HVB dropped 6%, 12v had no issues (keep in mind my car is 4.5 years old, so old 12v battery).

It seems to be overkill to leave it on and running for that long.

 

[Bad Dolphin]

You're going to leave the vehicle running, for days on end, to keep the 12v charged? Umm....

 

[Bad Dolphin]

Oh, no...we live on an island so distances driven are very small. Our experience with our ICE cars is that the 12v batteries die prematurely because they are not kept topped off. So we've put them on trickle chargers and the problem is solved.

We've had a Tesla for 8 years. This was never an issue as the Tesla would top off its own 12v on a regular basis.

On this forum, I have read that our MME's do not do this. They only charge the 12v from the main battery if the 12v goes very low, and this leads to premature 12v expiration. There has been much talk about how to keep the 12v topped off, and most seem to recommend using a trickle charger attached to the battery or to its remote terminals. But this requires a rather cumbersome taking apart of certain elements in the frunk.

Ford not using software to regularly top off the 12v from the HV battery seems to be a design flaw.

Plugging in to the cigarette lighter (which we do in both of our other vehicles) seems to be a better solution. So I'm looking for info as to how to keep the cigarette lighter active.

An advisor at the Ford help line said that plugging it in overnight would work fine. She did not seem very knowledgeable, though, so I'm here and believe your advice over hers.

Any way to maintain an active 12v connection through the cigarette lighter to trickle charge the 12v?

 

[thenew3]

Oh, no...we live on an island so distances driven are very small. Our experience with our ICE cars is that the 12v batteries die prematurely because they are not kept topped off. So we've put them on trickle chargers and the problem is solved.

We've had a Tesla for 8 years. This was never an issue as the Tesla would top off its own 12v on a regular basis.

On this forum, I have read that our MME's do not do this. They only charge the 12v from the main battery if the 12v goes very low, and this leads to premature 12v expiration. There has been much talk about how to keep the 12v topped off, and most seem to recommend using a trickle charger attached to the battery or to its remote terminals. But this requires a rather cumbersome taking apart of certain elements in the frunk.

Ford not using software to regularly top off the 12v from the HV battery seems to be a design flaw.

Plugging in to the cigarette lighter (which we do in both of our other vehicles) seems to be a better solution. So I'm looking for info as to how to keep the cigarette lighter active.

An advisor at the Ford help line said that plugging it in overnight would work fine. She did not seem very knowledgeable, though, so I'm here and believe your advice over hers.

Any way to maintain an active 12v connection through the cigarette lighter to trickle charge the 12v?

One of the OTA software updates in the last year or so solved this issue. It will keep the 12v sufficiently charged.

I believe that's why my HVB dropped 6% over 29 days. It was using the HVB to keep the 12v charged.

We drive very little as well (work from home) and I also use a trickle charger on my ICE cars, but have not had to do that for the MME.

(My wife commutes to work, but puts less than 3k miles on her car a year, our large SUV for family trips is only used once every few months, the rest of the time it sits in the garage. the MME is now the grocery getter, and is used once or twice a week around town.)

 

[Bad Dolphin]

One of the OTA software updates in the last year or so solved this issue. It will keep the 12v sufficiently charged.

I believe that's why my HVB dropped 6% over 29 days. It was using the HVB to keep the 12v charged.

We drive very little as well (work from home) and I also use a trickle charger on my ICE cars, but have not had to do that for the MME.

(My wife commutes to work, but puts less than 3k miles on her car a year, our large SUV for family trips is only used once every few months, the rest of the time it sits in the garage. the MME is now the grocery getter, and is used once or twice a week around town.)

Thank you. Very helpful. We have a new 2024 MME GT. We took it to the dealer for the recent recall updates. Is there any way that we can verify that the OTA update to which you are referring has been done to our vehicle? Since we purchased in April, nonOTA's have been offered (we do have the default OTA schedule activated, and the car is garages directly under a high speed Internet repeater.)

 

[HuntingPudel]

A month or less should require no special treatment other than just driving the car (or just leaving it on) for about half to three quarters of an hour the evening before you leave.

Since you have a trickle charger you could just wire the charger’s quick disconnect to the battery positive and chassis ground and plug it in. It seems the simplest solution.

 

[thenew3]

Thank you. Very helpful. We have a new 2024 MME GT. We took it to the dealer for the recent recall updates. Is there any way that we can verify that the OTA update to which you are referring has been done to our vehicle? Since we purchased in April, nonOTA's have been offered (we do have the default OTA schedule activated, and the car is garages directly under a high speed Internet repeater.)

Maybe you can go to the thread where folks have FDRS and can look up info on your car to see what's installed and what's pending.

 

[thenew3]

A month or less should require no special treatment other than just driving the car (or just leaving it on) for about half to three quarters of an hour the evening before you leave.

Not sure that will do much. I've tested that a handful of times. Leaving my car parked in the garage in the "on" mode with lights, hvac, radio turned off. After 8 hours like that, the 12v SOC only goes up by about 2-3%.


What I do when I need to get the car to charge the 12v is to plug it into my L2 charger, set the L2 EVSE to the lowest current level possible (in my case 6 amps), and let it sit. Doing this will charge the 12v by about 3-4% per hour. Leaving it like this overnight can get the 12v into the upper 80 to lower 90% SOC.

 

[ChrisO]

I was sort of curious about charging when just on in accessory mode. I haven't driven my Mach-E in a few days, and it wasn't plugged in to the charger. When I plugged in the scanner the state for charge the 12v battery was at 75%.

And it did start charging the 12V battery. And there is a definite charge curve. At first it was gaining 1% in less than a minute, then 1 minute, and then 1.5 minutes, 2 minutes, ... I turned it off when it got to 83%, that took 21 minutes.

 

[Adventureboy]

Thank you. Very helpful. We have a new 2024 MME GT. We took it to the dealer for the recent recall updates. Is there any way that we can verify that the OTA update to which you are referring has been done to our vehicle? Since we purchased in April, nonOTA's have been offered (we do have the default OTA schedule activated, and the car is garages directly under a high speed Internet repeater.)

Your 2024 will be fine. My 2022 is fine since the updates in 2023. You need not worry about this for a two to three-week vacation. Leave it at 50-60% SOC unplugged, enjoy your vacation and come back to a happy car.

 

[Bad Dolphin]

Your 2024 will be fine. My 2022 is fine since the updates in 2023. You need not worry about this for a two to three-week vacation. Leave it at 50-60% SOC unplugged, enjoy your vacation and come back to a happy car.

Thanks again. But I was unclear--the OP was for a vacation and I'm inquiring about everyday 12v battery maintenance for longevity.

So if the HV battery now daily tops off the 12v, I'm good. But if it waits for the 12v to get low on charge first (as some forum chains have suggested) I'm looking for a solution.

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