Do these 12v battery issues exist in the 2025 model?

[joshtb86]

Do the same issues exist in the 2025 models? Dying early etc?

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[Ncasini]

Do the same issues exist in the 2025 models? Dying early etc?

YES
Battery swelling too
Check all connections on the battery. I mean ALL connections.
i found them loose and somewhat oxidized. Check under the BMS on the negative terminal. Mine was not tight and could hear a hissing sound like a loose connection. I cleaned the oxidation off the contact areas and used dielectric grease (silicone) on all the connections and made all the connections tight.
I bought a NAPA battery. ( there are only 2 manufacturers of this battery, one with the waffled sides like Ford, etc or flat sides like the NAPA. Don’t forget to reset the BMS.
And a 5 amp CTEK battery maintainer.

 

[joshtb86]

YES
Battery swelling too
Check all connections on the battery. I mean ALL connections.
i found them loose and somewhat oxidized. Check under the BMS on the negative terminal. Mine was not tight and could hear a hissing sound like a loose connection. I cleaned the oxidation off the contact areas and used dielectric grease (silicone) on all the connections and made all the connections tight.
I bought a NAPA battery. ( there are only 2 manufacturers of this battery, one with the waffled sides like Ford, etc or flat sides like the NAPA. Don’t forget to reset the BMS.
And a 5 amp CTEK battery maintainer.

Battery maintainer like a trickle charger? Are you plugging that into the pro power bed in the frunk? Got a solar one that plugs directly in to the OBD2 port for on the battery itself

 

[El Duderino]

2025 Flash owner here.

No low battery issues except for one after dealer performed recall via software update in my driveway. I think the 12v battery got drawn done further than normal via FDRS updates.

I completed a long Level 2 AC charge at very low rate (2,200 watts) and it charged the 12v backup to full.

I like low rates of level 2 charging when I can get away with it. My Emporia EVSE has adjustable charging from 6 amps up to 48 amps. I can change it in the app from my phone. Very convenient.

Current charge rate (240v * 10a = 2400w. Then some losses in conversion gets approx 2,200 watts shown in Ford Pass app)

 

[RickLightning]

Battery maintainer like a trickle charger? Are you plugging that into the pro power bed in the frunk? Got a solar one that plugs directly in to the OBD2 port for on the battery itself

No, you don't want to use the truck outlets to power a battery maintainer that charges the 12v battery...

If you use a battery maintainer, either connect it to the jump posts, or make sure the negative is south of the BMS connector.

 

[Heliian]

Mine lasted 3 years and 3 very cold winters before I proactively replaced it before leaving the truck parked for a week unplugged at - 25 deg C this year. Bought a new one from ford that has a 3 year warranty. No problems.

cleaned the oxidation off the contact areas and used dielectric grease (silicone) on all the connections and made all the connections tight.

I hope the order was clean, then tighten, then apply the dielectric grease over top.

 

[RickLightning]

Mine lasted 3 years and 3 very cold winters before I proactively replaced it before leaving the truck parked for a week unplugged at - 25 deg C this year. Bought a new one from ford that has a 3 year warranty. No problems.


I hope the order was clean, then tighten, then apply the dielectric grease over top.

Yeah, many improperly use dielectric grease.

 

[joshtb86]

No, you don't want to use the truck outlets to power a battery maintainer that charges the 12v battery...

If you use a battery maintainer, either connect it to the jump posts, or make sure the negative is south of the BMS connector.

Truck outlet to power the charger sorry should have clarified

 

[joshtb86]

Yeah, many improperly use dielectric grease.

What do you mean just put on top?

 

[RickLightning]

Truck outlet to power the charger sorry should have clarified

You don't want to use ProPower to power a device that is used to charge the 12v battery.

What do you mean just put on top?

It is non-conductive. If you coated the battery terminals, then put on the clamps, remove them and clean all the grease off. Apply the clamps and then tighten. Then, apply the dielectric grease if you see it (totally unnecessary).

 

[MountainAlive]

I’m going to jinx myself here but the 12v on my 2023 has been fine. I drive my truck every day though so it rarely sits. And I don’t leave any accessories plugged in when the truck is off except for the FITCAMX dashcam, but that’s connected to the rear view mirror power which shuts down when the truck is off. If your truck sits for several days in sub freezing temperatures then the 12v might go sooner.

 

[Heliian]

What do you mean just put on top?

Dielectric grease is to keep out moisture and prevent conductivity.

A contact enhancer goes on the connections prior to assembly to make it more conductive. Deoxit is probably the most available. Stabilant 22 is another popular contact enhancer but it's incredibly expensive. I use stabilant on aircraft, never had the need on a battery though.

There are various other battery contact cleaners but never used those either. Purple Scotch brite works well enough for me.

 

[djwildstar]

Do the same issues exist in the 2025 models? Dying early etc?

Ford has not significantly changed the 12V battery management.

In general, the lifespan of 12V batteries in EVs is about the same as in gas cars, roughly 3-6 years, mainly depending on your climate: the hotter it is, the quicker 12V AGM batteries will die.

Unlike gas cars, most EVs have electronic locks and latches, which sets up a catch-22: you can't access the vehicle without 12V power, but you can't jump-start the vehicle or replace the 12VB battery until you can access it.

This isn't the case with the Lightning: you can access the vehicle to jump-start it using only the key that's inside the keyfob. That plus a lithium-ion jump box (or another car with jumper cables) is all you need to get going again.

 

[Kansan]

Ford has not significantly changed the 12V battery management.

In general, the lifespan of 12V batteries in EVs is about the same as in gas cars, roughly 3-6 years, mainly depending on your climate: the hotter it is, the quicker 12V AGM batteries will die.

Unlike gas cars, most EVs have electronic locks and latches, which sets up a catch-22: you can't access the vehicle without 12V power, but you can't jump-start the vehicle or replace the 12VB battery until you can access it.

This isn't the case with the Lightning: you can access the vehicle to jump-start it using only the key that's inside the keyfob. That plus a lithium-ion jump box (or another car with jumper cables) is all you need to get going again.

There were updates to the 12v BMS over the past year. Those greatly improved how my 24 Flash manages the 12v battery - it was very evident this winter. I recall getting one or two updates OTA that affected the 12v system but I’m not sure if there were others - I keep my trucks updated with FDRS and you don’t get the nice summary when you update that way.

 

[chl]

Any an all 12v lead acid batteries will last longer if on a maintainer when not in use.
The reason is sulfate build up on the plates.

If the battery is not fully charged to 100% after use, the sulfates that form as a result of the chemical process of releasing stored energy will not be driven off of the plates in the battery back into the electrolyte, and they become a permanent coating reducing the ability of the battery to deliver energy.

Over time the sulfate build-up will 'kill" the battery's ability to deliver energy.

A battery maintainer will top off the battery to 100% and avoid this problem, using a low current to avoid another potential battery issue - overheating leading to swelling, loss of electrolyte and out-gassing of hydrogen gas. That has been seen in some Lightnings as well as the early death.

If you don't use a maintainer, you might get 2-5 years out of an AGM battery depending of driving habits, etc., before needing to replace it. Maybe that's enough for some, but there are many Lightning system components that are critically dependent on the 12v battery system.

From Lightning owner reports here and elsewhere, the lower end of the lifespan range seems to be a frequent occurrence.

When the 12v battery gets weak, the truck begins to shed loads, and then various error messages begin to show up indication problems with a variety of the truck's systems that can be disconcerting, even though they are due to the weak 12v battery.

OTAs may fail to install and you could even end up being stranded and needing a tow.

I have the original 12v battery (flooded not AGM) in my 2012 Nissan Leaf that has been on a maintainer since about March of 2012 and still does fine - that's over 14 years. I measured the SOH (state of health) recently and it was at 80%, about the threshold for replacement. So maintainers really work.

Maybe you've already seen these, but just in case:

About putting trickle charger/maintainers on the battery and how to make it easier by adding a trickle charger wire:
https://www.f150lightningforum.com/forum/threads/charging-12v-battery.16979/

The maintainer negative should be connected downstream of the BMS sensor as shown about, or to any chassis ground - just DO NOT connect it to the actual negative battery terminal which would by-pass the BMS sensor.

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