F-150 Lightning Electrical System Overview – w/ 12v Battery, Power and Ground Points

[beatle]

The bms for any EV 12-volt is pretty sophisticated, and presumably specific to the battery type, so just tossing a different charge-type into an EV seems a bit riskier than in an ICE. Tesla apparently did a lot of engineering to make the switch to lithium 12-volt batteries last year.

The 12v battery in my Model S threw a warning early last year and Tesla replaced it with another AGM. Even though the battery chemistry was the same as the original, the tech had to update the firmware to reflect the new battery - not just "reset" the warning. I like to think if this were not important they wouldn't waste their time updating the firmware to account for even small changes in the battery.

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[PungoteagueDave]

The 12v battery in my Model S threw a warning early last year and Tesla replaced it with another AGM. Even though the battery chemistry was the same as the original, the tech had to update the firmware to reflect the new battery - not just "reset" the warning. I like to think if this were not important they wouldn't waste their time updating the firmware to account for even small changes in the battery.

Agreed, I wouldn't mess with changing anything associated with electronics/batteries on any EV, especially while under warranty. I tear into my motorcycles immediately on delivery, replacing suspension, lighting, seats, windshields, pegs, exhausts, headers, batteries, turning a $28k purchase into $40k right up front, but that doesn't affect warranty, as most mods are factory-ok. On a 600-lb BMW GSA, cutting a 16-lb battery to 3 lbs is a big difference, given how top-heavy those bikes are. The same is true for stainless-to-titanium exhaust and headers conversion, especially if dropping the catalytic converter and exhaust flapper systems. Doing the same on a car or truck is meaningless, and IMO, risky.

 

[FlasherZ]

The 12v battery in my Model S threw a warning early last year and Tesla replaced it with another AGM. Even though the battery chemistry was the same as the original, the tech had to update the firmware to reflect the new battery - not just "reset" the warning. I like to think if this were not important they wouldn't waste their time updating the firmware to account for even small changes in the battery.

After we blew through the warranty in our 2016 Model X (now at 157k miles), I replaced its AGM battery with the Ohmmu model back in 2019-ish (I think?). Knock on wood, have had no problems so far.

I didn't do it for weight reasons, I did it to try something for longevity. Been driving Tesla since 2012 and EV's are considerably tougher on lead-acid batteries compared to typical starting batteries because of the car's deep-cycle nature/treatment.

My first 12V replacement in Model S came after only 6 months, in April of 2013. They've since gotten much better at treating those batteries, but they're still looking for something better I think. I've replaced 6 or 7 12V batteries across Model S (2012/2016/2018 models) and Model X (2016) in 10 years.

 

[metroshot]

Does the USB-C and USB-A power come from the 12V AGM battery ?

 

[Lui]

The AntiG battery will not work.
1st; it wont fit, H5 is over 2" longer...
2nd, the AG's " restart feature will disconnect the battery early and not allow the battery to cycle
below 13V.

Both wrong. See below pic the 12v battery tray is at least 3+" longer. Also see attached the 12v battery state of charge graph, during idle (mach e). The dc dc will kick in to maintain the battery charged in idle or while charging. I have asked AG tech team and they said the threshold for the re-start feature to kick is around 11.5V and that is lower than the ford threshold module, which around 12v. So all boxes r covered.

 

[LiBatt]

ok, a longer bigger battery will fit. I cant wait to spend $660+ on a new battery !

 

[bms72]

Has anyone replaced the LVB in their lightning with an Ohmmu yet? If so, how is it working?

 

[Citizen0]

Yes it can stay switched on while driving.

I can confirm the 110 outlets can be enabled while driving. I pulled a parade float last year and ran an amp and speakers for the float from the rear outlets. If I accidently leave the cover open in the frunk (have to show off all the bells and whitles sometimes, lol) I get a prompt on the center display asking if I want to continue providing power to those outlets.

Check the amperage of the 110 outlets too though. Some may be limited to certain wattage. I remember my old C-Max had a 110 for the rear seats, but it was limited to 150w.

 

[Dolio]

Also see attached the 12v battery state of charge graph, during idle (mach e). The dc dc will kick in to maintain the battery charged in idle or while charging. I have asked AG tech team and they said the threshold for the re-start feature to kick is around 11.5V and that is lower than the ford threshold module, which around 12v. So all boxes r covered.

Thanks for posting this graph. And I also noticed that the Lightning (and Mach-e) keep the 12v battery charged up during long periods of the vehicle being off. AFIKT this is a relatively new behavior as far as cars and other BEVs go. I do not believe that my Leaf nor my Bolt would do this, and I also do not think my PHEV Prius(2012) nor current Pacifica Hybrid (2018 PHEV-33Mi) have this feature.

I was thrilled to learn this because I was using s dumb ~300watt APC UPS with a 50Ah ~12v LiFePo4 battery under the back seat to run about 100watts (~12v*8amps) for roughly a week. It was also connected to the cab AC outlet, but it would never charge the Li battery because it only had about 10watts worth of charger and the voltage was slightly too high. And so I would swap out that LiFePo4 every week or so when it was finally dead and charge it back up outside the truck. Plus all the conversion losses involved with this Rude Goldburg, as the actual load is probably about 50watts or less.

Anyway... I recently tore out all this APC UPS bs and just tapped a few of the unused fuses in the passenger foot well kick panel instead. Since the truck will keep the 12v accessory battery topped up on it's own! Has been working well enough for a week or so now. Only adverse side effect is that now I get this warning in the ford pass app, and on the speedo screen every few days:

ELECTRICAL SYSTEM DRAIN SERVICE REQUIRED Today at Some:Time AM​

There is an electrical drain in LightningName, possibly caused by after-market device(s). If that's not the case, please schedule service soon.​

Since this is an "after-market device", I have just been ignoring this warning, which should be fine. I also got the monthly health check email, and it did not include any mention of this warning that I had got a few days before the health check email. I intend to hook up a data logger and generate my own graph similar to the one you have shared here. So thanks for the bread crumb and inspiration.

Regarding others discussion about adding large loads, and the ~55amps available. I believe that is the continuous current available given that all of the other stock 12v accessory loads were also fully running, which would be pretty rare I would imagine. Some of the higher load accessories mentioned were also periodic items like a winch or snow plow blade hydraulics. Since these types of loads would have a short duty cycle, I think it would be safe to use them without much modification. Its not as if running a 200amp load for a few seconds would overload the DC-DC converter. First the converter would probably have nearly that much overhead available. Second, the 12v battery would be picking up any slack that the DC-DC wasn't supplying. And Finally, Adding a load larger than the DC-DC doesn't immediately overload it, the 12v battery would need to be depleted first, and even then the converter will only supply what it is capable of and be under voltage or shut itself down if it couldn't make some minimum voltage... I would imagine. It would probably be a good idea to add your own 12v battery and a fuse, if not your own current limited dc-dc converter between the stock battery and your addon, if you plan on running a very heavy accessory that will have a very high duty cycle... But then again, we have about 6+3kva worth of 110/220vac @30 amps from which to drive something so big. That dwarfs the 12v*55a (0.6kva) of native 12v accessory overhead. Anyway, if any aftermarket outfitter needed more power than this... We do have a massive HV battery that ford might help them tap into sort of how the home power backup works.

 

[Maquis]

Thanks for posting this graph. And I also noticed that the Lightning (and Mach-e) keep the 12v battery charged up during long periods of the vehicle being off. AFIKT this is a relatively new behavior as far as cars and other BEVs go. I do not believe that my Leaf nor my Bolt would do this, and I also do not think my PHEV Prius(2012) nor current Pacifica Hybrid (2018 PHEV-33Mi) have this feature.

I was thrilled to learn this because I was using s dumb ~300watt APC UPS with a 50Ah ~12v LiFePo4 battery under the back seat to run about 100watts (~12v*8amps) for roughly a week. It was also connected to the cab AC outlet, but it would never charge the Li battery because it only had about 10watts worth of charger and the voltage was slightly too high. And so I would swap out that LiFePo4 every week or so when it was finally dead and charge it back up outside the truck. Plus all the conversion losses involved with this Rude Goldburg, as the actual load is probably about 50watts or less.

Anyway... I recently tore out all this APC UPS bs and just tapped a few of the unused fuses in the passenger foot well kick panel instead. Since the truck will keep the 12v accessory battery topped up on it's own! Has been working well enough for a week or so now. Only adverse side effect is that now I get this warning in the ford pass app, and on the speedo screen every few days:

ELECTRICAL SYSTEM DRAIN SERVICE REQUIRED Today at Some:Time AM​

There is an electrical drain in LightningName, possibly caused by after-market device(s). If that's not the case, please schedule service soon.​

Since this is an "after-market device", I have just been ignoring this warning, which should be fine. I also got the monthly health check email, and it did not include any mention of this warning that I had got a few days before the health check email. I intend to hook up a data logger and generate my own graph similar to the one you have shared here. So thanks for the bread crumb and inspiration.

Regarding others discussion about adding large loads, and the ~55amps available. I believe that is the continuous current available given that all of the other stock 12v accessory loads were also fully running, which would be pretty rare I would imagine. Some of the higher load accessories mentioned were also periodic items like a winch or snow plow blade hydraulics. Since these types of loads would have a short duty cycle, I think it would be safe to use them without much modification. Its not as if running a 200amp load for a few seconds would overload the DC-DC converter. First the converter would probably have nearly that much overhead available. Second, the 12v battery would be picking up any slack that the DC-DC wasn't supplying. And Finally, Adding a load larger than the DC-DC doesn't immediately overload it, the 12v battery would need to be depleted first, and even then the converter will only supply what it is capable of and be under voltage or shut itself down if it couldn't make some minimum voltage... I would imagine. It would probably be a good idea to add your own 12v battery and a fuse, if not your own current limited dc-dc converter between the stock battery and your addon, if you plan on running a very heavy accessory that will have a very high duty cycle... But then again, we have about 6+3kva worth of 110/220vac @30 amps from which to drive something so big. That dwarfs the 12v*55a (0.6kva) of native 12v accessory overhead. Anyway, if any aftermarket outfitter needed more power than this... We do have a massive HV battery that ford might help them tap into sort of how the home power backup works.

The 12V is only charged when the truck is on or charging. You are getting the warning because you are depleting the 12V battery.

 

[TaxmanHog]

The BCM / PCM does initiate the LVB charging process with KEY OFF as well, IF no faults or exceptions are present.

 

[Maquis]

The BCM / PCM does initiate the LVB charging process with KEY OFF as well, IF no faults or exceptions are present.

Wow, that’s completely different than the Mach-E.

 

[Dolio]

The 12V is only charged when the truck is on or charging. You are getting the warning because you are depleting the 12V battery.

That is not the case, unless you know something that invalidates the official "Police Modifier Bulletin"? It's literally right there in the document attached to the first post of this thread (f150-lightning-electrical-system-overview.pdf). And its also apparent from the chart that I quoted from someone (LUI) who tested first hand this feature in their Mach-e. It also says that this is a feature in all plug in vehicles, So I presume it should also work in their plug in hybrids (Does ford do a PHEV Escape hybrid? shrugs?)

" Recommendation​

The 220A DC-DC converter and range battery pack standard on the F-150 Lightning Pro trim level can be used for applications that add aftermarket equipment such as lighting, radios, video, computers, video, spot lamps, surveillance, radar, etc. There are 55 Amps available for aftermarket equipment.​

...​

While ignition is off, if 12V battery reaches 40% state of charge, then vehicle waits 48 hours , before the DC-DC transfers 300 Watt-hours of energy to recharge the 12V battery. The HV power comes from either HV battery or wall power while on plug. If the 12V battery state of charge reaches 30%, then this HV to LV energy transfer happens immediately with no delay.​

...​

HV to LV Energy Transfer​

The HV to LV Energy system is providing energy transfer from the HV battery to the low voltage battery to prevent non-start condition when vehicle has been keyed-off for extended time. This is to avoid non-start conditions of empty LV battery and the system is only available to electrified plug-in vehicle only. The feature document is to provide high level requirements to develop functional requirements and implementation.​

...​

Conditions where High Voltage (HV) to Low Voltage (LV) Energy Transfer is not supported​

...​

The Battery Monitoring is clamped directly to the negative terminal of the battery and grounds to the vehicle at the chassis ground connection point... External customer loads must only be connectred to the vehicle at the customer battery connection point. If an eternal(sic:external) customer load is connected at the negative battery post, the Battery Monitoring Sensor accuracy cannot be guaranteed..."​

Granted, they do also warn that using this frequently will wear out the 12v battery earlier. Which should be obvious since using any device contributes to it's lifecycle timespan rating. It states that the lightning has a 35AH battery, so about 420Wh but it catches it at 30% minimum SoC so at most it should let 294Wh get consumed. Of if longer than a 48hour window it kicks in at 40$ or 252Wh worth. As I look back, I have three loads that are each 1-3watts. So I'll call it 10watts, and they will burn 240Wh per day. So they should be triggering the exception for use more than once per 48 hours and hitting that 30% limit. And I assume that is why I am being notified.

I had considered adding my own secondary 12v battery system, but that would mostly add a bunch of extra complexity that this HV-LV Energy Transfer feature is basically built to deal with. I was absolutely thrilled when I found this thread because I've always thought that hybrids, PHEVs, and BEVs should have a feature like this! And finally we do for Ford at least... Does anyone know if there is a comparable feature in other BEVs like the Chevy Bolt or Teslas?

 

[Maquis]

That is not the case, unless you know something that invalidates the official "Police Modifier Bulletin"? It's literally right there in the document attached to the first post of this thread (f150-lightning-electrical-system-overview.pdf). And its also apparent from the chart that I quoted from someone (LUI) who tested first hand this feature in their Mach-e. It also says that this is a feature in all plug in vehicles, So I presume it should also work in their plug in hybrids (Does ford do a PHEV Escape hybrid? shrugs?)

" Recommendation​

The 220A DC-DC converter and range battery pack standard on the F-150 Lightning Pro trim level can be used for applications that add aftermarket equipment such as lighting, radios, video, computers, video, spot lamps, surveillance, radar, etc. There are 55 Amps available for aftermarket equipment.​

...​

While ignition is off, if 12V battery reaches 40% state of charge, then vehicle waits 48 hours , before the DC-DC transfers 300 Watt-hours of energy to recharge the 12V battery. The HV power comes from either HV battery or wall power while on plug. If the 12V battery state of charge reaches 30%, then this HV to LV energy transfer happens immediately with no delay.​

...​

HV to LV Energy Transfer​

The HV to LV Energy system is providing energy transfer from the HV battery to the low voltage battery to prevent non-start condition when vehicle has been keyed-off for extended time. This is to avoid non-start conditions of empty LV battery and the system is only available to electrified plug-in vehicle only. The feature document is to provide high level requirements to develop functional requirements and implementation.​

...​

Conditions where High Voltage (HV) to Low Voltage (LV) Energy Transfer is not supported​

...​

The Battery Monitoring is clamped directly to the negative terminal of the battery and grounds to the vehicle at the chassis ground connection point... External customer loads must only be connectred to the vehicle at the customer battery connection point. If an eternal(sic:external) customer load is connected at the negative battery post, the Battery Monitoring Sensor accuracy cannot be guaranteed..."​

Granted, they do also warn that using this frequently will wear out the 12v battery earlier. Which should be obvious since using any device contributes to it's lifecycle timespan rating. It states that the lightning has a 35AH battery, so about 420Wh but it catches it at 30% minimum SoC so at most it should let 294Wh get consumed. Of if longer than a 48hour window it kicks in at 40$ or 252Wh worth. As I look back, I have three loads that are each 1-3watts. So I'll call it 10watts, and they will burn 240Wh per day. So they should be triggering the exception for use more than once per 48 hours and hitting that 30% limit. And I assume that is why I am being notified.

I had considered adding my own secondary 12v battery system, but that would mostly add a bunch of extra complexity that this HV-LV Energy Transfer feature is basically built to deal with. I was absolutely thrilled when I found this thread because I've always thought that hybrids, PHEVs, and BEVs should have a feature like this! And finally we do for Ford at least... Does anyone know if there is a comparable feature in other BEVs like the Chevy Bolt or Teslas?

That bulletin states specifically that it applies to the Pro trim. Do we know for certain that other trims behave the same way?

 

[Dolio]

That bulletin states specifically that it applies to the Pro trim. Do we know for certain that other trims behave the same way?

I have been using an aftermarket accessory that is using about 3~10watts for the past month, since 20230329. So that should be using 72~240Wh per day... Given that "the lightning has a 35AH battery, so about 420Wh but it catches it at 30% minimum SoC so at most it should let 294Wh get consumed" per triggering of the "HV to LV Energy Transfer" feature.

This fits my observations, in that over the weekends when I sometimes do not drive the truck for more than a day, or when I do I am making very short trips which might not have time to fully recharge the 12v battery... I am getting a FordPass app and in vehicle notification that says: "There is an electrical drain in TruckName, possibly caused by after-market device(s). If that's not the case, please schedule service soon." I got this notice 2023.{0402(2days off), 0407(2days off), 0414(1day off), 0416 & 0417(2days off and two consecutive days notification), 0423}. So I think this proves that the Lariat trim also has this feature.

Also, the bullitin states: "this is a feature in all plug in vehicles" so it should be present in all trims of all BEV vehicles. It makes sense in that it's really silly for a discharged 0.4kWh 12v battery to completely disable a vehicle with a 60~130kWh HV Traction battery pack that can easily keep the 12v charged for days to months even if a parasitic load is present in the 12v system...

Since I know my discharge is in fact caused by an "after-market device(s)" I have been recording but otherwise ignoring the notification. The wording of the notice indicates to me that no service is required if the user is aware of why there is an electrical drain.

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