Porpoise Hork
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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 October 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
10/6/25 Update:
After 19 days with the new BMS, multiple days of sitting parked or very short trips (less than 5 miles) I go out this morning and the SOC finally dipped from 100% to 85%. I immediately checked the actual voltage of the main battery and it was sitting at 12.68v. So the BMS SOC report was accurate. For once. Before the battery voltage would be 12.8-12.9 but show 80% SOC.
Instead of putting it on the charger I wanted to see how it would respond to the DC/DC charging the batteries, so I ended up driving around for about 40 minutes with the voltage pegged at 14.5v the entire time, then shut it off for about 5 hours. Just checked it and it's now showing 100% SOC with a resting voltage of 12.89v. With the old BMS it would either not have updated at all or gotten lower despite having been on charge for 4-5 hours or driven the same amount of time.
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 October 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
- Turn the ignition on (engine off), or press the start button without pressing the brake so the vehicle is in accessory mode.
- Flash the high beam headlights five times quickly.
- Now press the brake pedal three times quickly.
- If done correctly, the battery (BATT) icon on the dash will flash three times, confirming the reset.
10/6/25 Update:
After 19 days with the new BMS, multiple days of sitting parked or very short trips (less than 5 miles) I go out this morning and the SOC finally dipped from 100% to 85%. I immediately checked the actual voltage of the main battery and it was sitting at 12.68v. So the BMS SOC report was accurate. For once. Before the battery voltage would be 12.8-12.9 but show 80% SOC.
Instead of putting it on the charger I wanted to see how it would respond to the DC/DC charging the batteries, so I ended up driving around for about 40 minutes with the voltage pegged at 14.5v the entire time, then shut it off for about 5 hours. Just checked it and it's now showing 100% SOC with a resting voltage of 12.89v. With the old BMS it would either not have updated at all or gotten lower despite having been on charge for 4-5 hours or driven the same amount of time.
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