12V Issues with 2025 Flash 2 months Into New Ownership

[Tfarrell73]

Mine is 30. When I first got my OBD adapter I made the mistake of leaving the app open. This kept the Bluetooth active and keeps some truck modules running.

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[chl]

I have an OBD device for my Virginia Mileage Choice plan always plugged in always sending info to their satellite in bursts, never ran down my 12V battery.

Keeping your truck plugged in to a Ford Charge Station Pro will keep the 12V battery topped off, but I only do that in the winter when it goes below 40F to keep the HV battery warm. Not sure about other EVSE's - some say it might not be effective with the Ford Mobile Power Cord for example, or other lower amperage EVSEs, but I don't know.

Before having a couple battery related CSPs done on my 2023 Pro, I did experience trouble with getting OTA updates due to LV battery SOC being below 80% apparently - plugging the truck into the FCSP overnight solved that issue before the CSPs were done - since the CSPs no problems with OTA updates.

During an OTA update the DC-DC transfer of energy from HV to LV batteries is turned off by the way.

I did have one time when the Frunk failed to open after I had let the truck sit for approx a week without driving or charging (due to rainy weather and my schedule), but like you after turning the truck on for a few moments, the frunk opened fine. I had the CSP related to the Frunk before that incident, so I attributed it to maybe a low LV battery SOC because of lack of use/charging of the truck.

That said, several people have had troubles with the Lightning AGM batteries based on forum posts anyway and had them replaced under warranty.

Like any vehicle, many things in the Lightning may run off the 12V battery, when on and off, which can result in depleting the stored energy. Some have resorted to trickle chargers when the truck is not in use (hooked up to the jump posts inside the passenger side frunk top panel).

From all the troubles people have had, it is clearly a weak point in the Lightning design.

 

[ClevelandBeemer]

I have an OBD device for my Virginia Mileage Choice plan always plugged in always sending info to their satellite in bursts, never ran down my 12V battery.

Keeping your truck plugged in to a Ford Charge Station Pro will keep the 12V battery topped off, but I only do that in the winter when it goes below 40F to keep the HV battery warm. Not sure about other EVSE's - some say it might not be effective with the Ford Mobile Power Cord for example, or other lower amperage EVSEs, but I don't know.

Before having a couple battery related CSPs done on my 2023 Pro, I did experience trouble with getting OTA updates due to LV battery SOC being below 80% apparently - plugging the truck into the FCSP overnight solved that issue before the CSPs were done - since the CSPs no problems with OTA updates.

During an OTA update the DC-DC transfer of energy from HV to LV batteries is turned off by the way.

I did have one time when the Frunk failed to open after I had let the truck sit for approx a week without driving or charging (due to rainy weather and my schedule), but like you after turning the truck on for a few moments, the frunk opened fine. I had the CSP related to the Frunk before that incident, so I attributed it to maybe a low LV battery SOC because of lack of use/charging of the truck.

That said, several people have had troubles with the Lightning AGM batteries based on forum posts anyway and had them replaced under warranty.

Like any vehicle, many things in the Lightning may run off the 12V battery, when on and off, which can result in depleting the stored energy. Some have resorted to trickle chargers when the truck is not in use (hooked up to the jump posts inside the passenger side frunk top panel).

From all the troubles people have had, it is clearly a weak point in the Lightning design.

Yeah, I hope Antigravity develops a battery solution for the Lightning that solves these issues.

 

[Mal106]

My '25 Lightning is the 5th EV, hybred, plug in hybred I've had 12v battery problems with.

Yesterday I got in the truck and every light and warning concerning brakes was on. I called the dealer and left a message but never got a call back. Suspecting a 12v problem, I plugged it in and charged for a couple hours. 120v for 3kwh. That indeed fixed it.

I DID have an OBD dongle plugged in. Unfortunately I did not check the 12v voltage. The last update I received on May 19 was protection for the 12v battery, maybe not. Looks like Ford, Nissan and KIA could save the little LVB with all that stored energy on board.

As a point of interest NOT RECCOMENDED; I drove it. The brakes were horribly funky requiring excess pressure, grabbing and slow to release but ... they would stop the truck.

 

[ClevelandBeemer]

I had similar issues with mine. It turned out to be a bad frunk switch. The switch has been replaced 2 times under warranty. The second time it went bad I already had it in the shop for strange 12v battery issues The Text said that they had had a few of them in with strange battery issues that were related to the bad switch. When he checked the switch it was bad. He unplugged it and ordered the parts. It was a few days for the parts to come in, but as soon as he unplugged it, the 12 V battery issues stopped the new switches in and everything’s fine now.

Turns out I think the frunk exterior switch is bad. It’s maybe working 30% of the time now. Dealer appointment scheduled and hopefully this resolves the issue.

 

[chl]

Turns out I think the frunk switch is bad. It’s maybe working 30% of the time now. Dealer appointment scheduled and hopefully this resolves the issue.

Mine (the outside switch) sometimes requires two pushes to function, about 10% of the time maybe. The inside switch always works the first time unless the battery is low.

 

[ClevelandBeemer]

Mine (the outside switch) sometimes requires two pushes to function, about 10% of the time maybe. The inside switch always works the first time unless the battery is low.

Yeah, my issue is now pretty frequent on the exterior switch. I’m wondering if it’s causing a short as my truck has gone into “sleep” mode twice this week. Yet the battery is at 13V right this moment…..

 

[chl]

Yeah, my issue is now pretty frequent on the exterior switch. I’m wondering if it’s causing a short as my truck has gone into “sleep” mode twice this week. Yet the battery is at 13V right this moment…..

That does seem a likely scenario -strange reaction for pushing the Frunk button, so wires crossed/shorted somewhere seems likely to me.

 

[Ryanhu1234]

They had to replace the switch and the harness both had water damage

 

[bmwhitetx]

Yeah, my issue is now pretty frequent on the exterior switch. I’m wondering if it’s causing a short as my truck has gone into “sleep” mode twice this week. Yet the battery is at 13V right this moment…..

Are you using Home Assistant to check 12V in that screenshot? If so and you poll too often, that keeps the truck more awake and might drain 12V.

 

[ClevelandBeemer]

Are you using Home Assistant to check 12V in that screenshot? If so and you poll too often, that keeps the truck more awake and might drain 12V.

This is from LowJack.

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