Ford BMS issues, research, testing, and solution results

[gwb82]

I'm running the O'reilly Super Start Power Sport AGM Top Post Battery Group Size BTX14AH 220 CCA - ETX15 and the ECO-WORTHY 12V 20Ah Lithium piggyback with Cartman 4AWG 18-Inch cables.

The O'reilly battery is a fair bit taller and thicker than the OEM 7.5AH agm battery so some trimming needs to be done on the lower tray to fit it and on the battery itself so the terminals will bolt down. You'll need a longer bolt for the tie down strap to secure it and the lid won't completely close because of the increased thickness. I used black Gorilla duct tape to keep it down. Yeah.. I'm a redneck... I might end up swapping the bigger AGM out for a OEM sized one later on.

If you don't want to mess with all that then any parts house should have a direct replacement for the Ford BHAGM-AUX1-B auxiliary battery. You can then just get the 20AH or if you want more reserve capacity get a 30AH lithium cell instead. Definitely worth looking at Hammaman's testing an aux battery solution thread if you have not done so already.

Thanks much. I read all of your threads and Hammerman’s. You guys are on a much higher intellectual level than than I when it comes to the tech on my truck so I read as much as I can in order to learn. Much appreciated! And I live in South Carolina, speaking only for myself here…I understand redneck all too well lol.

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[Porpoise Hork]

Nothin wrong with a bit of redneck engineerin.

Hey guys. I just installed the new revision and while doing so I see there is a second BMS sensor on the aux battery as well. Any thoughts replacing it too?
Part number BT4Z-14B357-C.

From what I can find on it this is the battery current and temperature sensor. It works in tandem with the primary BMS to regulate a vehicles alternator or DC/DC (hybrid) output based on the battery temps. It allows the BMS to safely adjust charging voltages and currents, protecting the battery from thermal stress.

It doesn't appear that Ford has released any revisions for this part and has been in use on the F150 since 2011.

https://parts.lakelandford.com/p/Ford__/Sensor-Battery-Current-Temperature/51358760/BT4Z14B357C.html

My takeaway on this is that you'd have to closely monitor how much amperage the charging system is pushing to the battery at different temps to see how it's behaving to determine if it's reporting the correct data to the BMS or not. Also with it being located at the aux battery would mean that Ford is wanting to limit how much current is directed to the 7.5AH cell to prevent overheating and potential damage from electrolyte boil-off.

 

[Mosey]

I always learn new stuff here. Thanks.

 

[Porpoise Hork]

Same here and anytime sir. I learned more about Ford's BMS than I really wanted to with this endeavor. lol

 

[dadrew]

Maybe this is what I need to replace on my 21 PB, barely drove it over the weekend since my wife was in the hospital. Just a few times to and from there but mostly sat in the driveway

Go to start it Monday morning to take the dog to the vet and get the stop safely message and Christmas tree of lights all over the dash. I had been getting at random times charging system service soon message but would go away after a drive and battery charged up.

charged both batteries using this charger from Amazon for a few hours and seemed to take care of it once I drove it around, check engine light went away

https://www.amazon.com/dp/B007ESQW08?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_2&th=1

Replaced both the main under the hood battery with a Costco Interstate H7 battery, also replaced the 12v battery in the rear (just a new motorcraft) that was almost a year ago and still issues

truck is at 87k miles and warranty is up at 100k.....cant get into the dealer for at least a month and no loaner vehicle

idk maybe I just move on from it and get a new truck lolol

 

[dadrew]

maybe this is a dumb question so excuse my ignorance but is there a specific spot to put charging cables on the PowerBoost. It just seems different with the BMS and covers there so I wasn't 100% sure

 

[Snakebitten]

maybe this is a dumb question so excuse my ignorance but is there a specific spot to put charging cables on the PowerBoost. It just seems different with the BMS and covers there so I wasn't 100% sure

Nothing really special, but I put the chargers positive clamp on the positive post of the underhood AGM, and the negative clamp on the negative strap bolted to the right of the battery.

 

[dadrew]

Nothing really special, but I put the chargers positive clamp on the positive post of the underhood AGM, and the negative clamp on the negative strap bolted to the right of the battery.

I was putting the negative slightly to the left where the BMS is....maybe that's my issue

 

[Davexxxx]

I was putting the negative slightly to the left where the BMS is....maybe that's my issue

That is also "proper".

 

[dadrew]

I think Ford should hire most of the folks on this forum as engineers, we wouldn't have nearly the same amount of issues

 

[Snakebitten]

I'm willing to bet Ford has more than enough engineering prowess to address every issue any of us have with any of their products.

That's not the problem.

The problem is that the engineer designs a brilliantly capable valvebody for the 10r80, but by the time the co$t analysis folks get their hands on it the valve body no longer represents what the engineer intended. Which in turn leads to $millions in warranty expenditures, along with customer dissatisfaction with the product, all because of a remarkably small up front co$t savings in materials and composition.

Just switching metallurgy specs to save $15.00 (guesstimate) can be the difference between a 250,000 mile solid performing steel valvebody vs a transmission replacement during warranty. Or worse yet, at 100,000 miles and out of warranty?

Engineering wasn't the root cause.
Bean counting to a fault is.

No engineer would recommend a variable pressure oil pump for a 100+ HP per liter engine. EPA/CAFE pressure forces the engineer to design such a thing.

While defending the professional automotive engineer, I admit it's hard to defend some of the self-inflicted manufacturers conclusions of what the customer wants. (or doesn't want)

Ford thinks a Raptor buyer desires the active suspension options to be untethered from the drive mode options, but doesn't think the CCD F150 owner would care. There can't be a single suspension engineer that would believe such nonsense.

 

[PFXLT]

I must say it again, this damn forum keeps costing me money. Haha
Seems like an easy and cheap upgrade to a probable issue. Truck is late 2021 so I’m sure it’s the original faulty version. Found the part local, dated march 2024 and only cost me about $1.50 after using ford points.

 

[Mosey]

I must say it again, this damn forum keeps costing me money. Haha
Seems like an easy and cheap upgrade to a probable issue. Truck is late 2021 so I’m sure it’s the original faulty version. Found the part local, dated march 2024 and only cost me about $1.50 after using ford points.

Me too.

 

[ReverendQ]

This is the ongoing trials and tribulations I have dealt with on the Ford BMS system for my F150. My testing is ongoing but I wanted to go ahead and post how things have been going so far. There's a lot to sort through so I tried to break it up based on my experience, findings and results so far.

Early versions of Ford BMS sensors installed on 14th gen F150's reported to have issues with incorrect 12v and HV battery (PB versions) SOC, random SOC drops overnight of 10-20%, blocking of OTA updates, modules being put into deep sleep/failing to power up correctly due to inaccurate SOC readings leading to errors or warnings in both the FordPass app and cluster on startup.

Since I began monitoring the 12v SOC levels 6 months ago I have noticed some odd voltage related behaviors. I have had the 12v SOC set to 100% for the majority of time I have owned the truck and have a 20AH lithium battery piggy backed to the 7AH AUX battery for 3ish months now. The main battery is 14 months old and has tested good. The aux battery was original but also tested good.

Behaviors observed: I have seem random overnight drops in 12v SOC from 100 to 90-80% along with a drop in the HV battery SOC from 55-60% to under 35%. No OTA updates received or other indications leading to the drain issues. No alerts sent from the truck, no modules put into deep sleep but the low HV charge level would cause the truck to use the flywheel starter on system startup. This would happen at least 1-2 times a week but has progressively gotten worse over time. The random flywheel startup has been present since day one of truck ownership. Since I only recently started monitoring the SOC, I can only assume the voltage drop problem has been present since I bought the truck.

Testing:

Battery voltages taken: When BMS reports 80% SOC (overnight drop from 100%), voltages reported with handheld meter show resting primary 12v at 12.86v, aux battery 12.84v, and 20ah battery 12.62v. All showing 99-100% SOC when comparing to industry standards for their battery types.

Steps to attempt to correct the behavior when SOC drop appeared: Leaving the truck off for 8+ hours to see if it would update the SOC but still reports as low despite resting voltages showing otherwise. Charging all three batteries separately and allowing 6+ hours for AGM desulfation cycle to complete and Lithium cell balancing to complete at 14.8v.

Observation after charging: BMS may correctly update SOC levels but most of the time a 6-8 hour key off cycle required for correct SOC to report back. Incorrect SOC and random HV charge level drop occurrences still happens and increased to every 3-4 days despite having driven for 60+ miles the previous day.

Next Step to solve: Replaced Aux battery with 14AH AGM battery. Replacement charged for 6 hours before swap and tested 100% to make sure battery is healthy. BMS reset completed when aux battery replaced.

Observation: 12v SOC remained at 100% for 48 hours once BMS relearn completed then 12v dropped to 75% and HV dropped to 37% after being parked for 12 hours, 12v battery voltages again reported all at 100% SOC despite BMS reporting low. No OTA received.


Research / Findings:
This is when I started looking into replacing the BMS and here is what I discovered about the piece of crap.
Ford has had numerous issues with BMS modules produced from late 2020 to late 2023. Issued include the state of charge on affected vehicles to randomly drop by 10-20% overnight. Anecdotal reports also found that Powerboost HV battery levels also fell to below 40% despite being at 60% at key off when 12v SOC dain incidents happened. Ford has issued a Customer Satisfaction Program 23B70 replace BMS modules with part numbers NL3T-10C652-AC and NL3T-10C652-AD but when I contacted the dealer they said mine was not included despite it having a build date of 1/27/21.

I found that Ford released their latest version of the BMS "ML3Z-10C679-B" in mid October of 2023 which is reported to have addressed all the known issues of the earlier versions, but may not have begun installing them until early December to use up existing inventory.


Issues reported - Early BMS revisions dates of manufacture.
NL3T-10C652-AC - October 2021 to October 2022
NL3T-10C652-AD - October 2022 to October 2023

Current BMS revision - ML3T-10C652-B - Manufacture dates of November 2023 to current.
Replacement cost is roughly $20 + shipping from most online OEM parts vendors.

The BMS will have the Ford engineering part number "ML3T-10C652-BA" stamped on it just under the FoMoCo marking regardless of the actual part number on the packaging when received. How to identify what version or associated part number your BMS is will be the production date that is directly under the engineering number. So when you get the part be sure to verify the build date of the part. It should be early 2024 but still want to verify it.



Testing possible solution: BMS replaced with current revision

It has been 12 days (as of this post) since I replaced the original BMS with a build date of 11-12-2021 for ML3T-10C652-B with a build date of 02-17-2024. So far zero issues with random 12v or HV SOC drops. No flywheel starts, no random park assist not available errors, no APIM delayed boot (sending welcome chimes to cluster) issues. Both 12v SOC has remained at 100% and HV charge levels remaining the same as at key off with no overnight drops.

I am still watching things but so far replacing the BMS appears to have resolved all the issues I have been having. For anyone with a 21-23 both PB and non-PB versions and having odd issues as those stated you may want to consider checking the build date on the BMS installed and replace it if it shows anything before 10/23.




Replacement: Time -5 minutes.

Steps to replace: Non PB models - Disconnect ground lead at BMS and remove BMS from negative terminal. Carefully unclip harness lead to old BMS (it's a very thin plastic clip) and replace with new one then reconnect. Perform BMS reset procedure. Allow 6-8 hours of key off for new BMS to "learn" current battery SOC level.

For PB models disconnect the negative terminal on Aux battery and then the main 12v battery to replace the BMS sensor and reconnect all terminals then perform the BMS reset.
Allow 6-8 hours of key off for new BMS to "learn" current battery SOC level.


Ford F-150 BMS Reset Steps

1. Turn the ignition on (engine off), or press the start button without pressing the brake so the vehicle is in accessory mode.
2. Flash the high beam headlights five times quickly.
3. Now press the brake pedal three times quickly.
4. If done correctly, the battery (BATT) icon on the dash will flash three times, confirming the reset.

I'll continue to monitor how the SOC and truck behaves and will post back if the SOC drop or other related issues happen to return.

Great stuff Bret!

Ironically, I just got the random inaccurate drop in SOC. For me, it occurs at a frequency of much longer than 12 days so I am looking forward to your update. My data is most likely skewed by using both a 30 mAh LiFePO Auxiliary Battery, Battery Problem? | Page 3 | F150gen14 -- 2021+ Ford F-150, Tremor, Raptor Forum (14th Gen) | News, Owners, Community, Discussions and a Solar charger for the main LensunSolar Hood Solar Panel F-150 Powerboost BAP/Tremor Hood Installation | F150gen14 -- 2021+ Ford F-150, Tremor, Raptor Forum (14th Gen) | News, Owners, Community, Discussions .

Thanks for the post with p/n and date code.

 

[ReverendQ]

Excellent work.

While I DO occasionally experience, or at least have experienced both the sudden drop in SOC for both LV and HV, it hasn't been often in recent months.

Still, I have every incentive to "upgrade" to the latest shunt/sensor.

Thanks for sharing.

Nerd.

Curious Bruce,

What is/are your incentive(s)? I was under the impression you (like me) implemented the LiFePO Aux Battery so your most likely at 100% SOC independent of the BMS reporting, and the BMS appears to get back on track with driving with a charge cycle. That is, I ignore it since I know I am not going to go low enough to cause module shut-downs, etc.

How are you determining the BMS if off-the-rails as compared to an actual drop in SOC due to OTA, even if a partial download or other Ford contact i.e. upload has/is happening while parked? Should I assume through the BT monitor you have?

Again, just curious,
ReverendQ Kevin

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