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airline tech

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What happened to the last post results - Chat GBT?
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TJC

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What happened to the last post results - Chat GBT?
I have just completed compiling the data into a 45 page document that a lot of us are going to find quite interesting. It was easier to do this as an attachment than to post multiple long messages. There is a lot of data in this document that explains / makes the BMS much clearer. I actually had Chatgpt reverse engineer a bit on Ford proprietary SOH algos... and it spit out a bit of pseudo code!

Here is a list of sections in the PDF document
  • 5G Ford Ranger BMS Overview
  • How does a 2020 Ford BMS calculate SOC?
  • How Does Ford monitor Battery SOH?
  • Why Incorrect SOH Causes Charging Problems
  • How to Reset BMS
  • How Ford calculates SOH (internal algorithm details)
  • What a correct SOH should look like by battery age
  • Diagnosing a Sulfated Battery
  • How to test your battery BMS sensor
  • How to test your alternator’s smart-charge command
  • How to test the battery temperature sensor
  • Normal Ford charging voltage by temperature chart
I find the SOH topics the most interesting. I've got to go over the data in detail... but I already know that Ford has a battery replacement date based upon the weighted criteria they use to determine SOH. SOC has 40%-50% weight, but age of battery is up there too.

Please read the attachment and let me know what you think. (You were not far off on many of your assessments.) But there are few details I know you will find interesting. The BMS is more complex than I assumed, with a lot of moving pieces. It is very dynamic.

I actually entered my data into Chatgpt and it told me with 100% certainty that my Battery SOC and SOH were an impossibility. Here is the exact exchange:
-------------------------------------------
"Quick Reality Check — You Can Use This to Confirm your Battery SOH

If you tell me:
  • Your SOH
  • Your battery age
  • AGM or flooded
  • Your climate
  • Alternator voltage behavior
I can tell you instantly if your SOH is correct or wrong."

I laughed out loud when it came back... I then reentered the data but with a 92% SOH (estimated) from what BMS reported on my last drive 2 days ago and got exactly the same result. Now I did recently reset BMS.. but that was well over 1.5 months ago, and I am confident that it has adjusted itself to the battery's SOH and SOC, and IR. and the absolute lowest SOC reading that the BMS has ever reported is 88% and it is regularly in the mid 90's. Both the Viking and TopDon report back SOH at 100%, and SOC at 100% quite regularly. But neither consider age... and I am not convinced that they should, at least not to the threshold that Ford does. Ford projects battery end of life at 5-6 years. with a SOH below 55%. See the embedded table.

Here's a quote from the document:

Here is the most accurate, realistic SOH-by-age chart for Ford vehicles with Smart Charge (BMS + PCM-controlled alternator). This data is based on:​
  • Ford engineering bulletins
  • Johnson Controls/Varta AGM aging curves
  • What FORScan users consistently report
  • Known behavior of Ford’s SOH estimator
This is not dealer fluff — it’s what you should actually expect to see.​
...​
...​
Ford’s SOH is therefore not just one test—it’s a rolling, adaptive calculation​
updated continuously.​

What Ford and by extension Chatgpt don't know is there is an onboard desultor installed that consistently keeps IR at new battery levels... and IR is weighted by Ford's algo at 50% in determining SOH per the docs Chatgpt provided me.

Anyway, Here was my response:

"Please confirm my Battery SOH, SOH 100%, Battery age 66 months, Battery is AGM, Raleigh, North Carolina Climate, Charge Voltage 14.1 - 14.4v."

And here is what Chatgpt replied:

Based on everything you provided, your Ford’s SOH = 100% is not possible and is definitely incorrect.

Let me break down why with engineering-level clarity.

⭐ Your Inputs
  • SOH: 100%
  • Battery age: 66 months (5.5 years)
  • Battery type: AGM
  • Location: Raleigh, NC (hot/humid summers, moderate winters)
  • Charge voltage observed: 14.1–14.4V (normal mid-temp charging)

⭐ REALITY CHECK: What SOH Should Be

Using the correct Ford SOH age table:

A 5.5-year-old AGM battery in North Carolina climate should realistically be:

45–70% SOH

(Depending on heat exposure, sulfation, charge cycles, and alternator behavior.)

Ford SOH cannot and does not stay at 100% on a 5+ year AGM.

SOH 100% is only normal for:
  • A new battery
  • A recently BMS-reset battery
…NOT for a 66-month AGM.

🚩 Conclusion: Your SOH Value Is Incorrect

Your SOH = 100% is not real.
It indicates a sensor/system reporting error, not an actual healthy battery.

🔍 Top causes when Ford reports false 100% SOH

One or more of these is almost guaranteed:

✔ 1. BMS was recently reset

SOH resets back to 95–100% automatically.
It takes weeks of driving for SOH to drop to its real value.

✔ 2. Incorrect battery type programmed (AGM vs Flooded)

Using “flooded” for an AGM can distort SOH and SOC.

✔ 3. Bad or drifting battery current sensor (MOST COMMON)


Symptoms:
  • SOH stuck high
  • SOC stuck 75–85%
  • GENFDC doesn’t respond to load properly
  • Charge current readings inaccurate
  • No SOH change over time
✔ 4. Bad battery temperature sensor

Incorrect temperature → incorrect resistance normalization → incorrect SOH.

✔ 5. Loose negative cable / corroded ground

Small voltage errors corrupt the SOH calculation.

✔ 6. Battery replaced long ago without BMS reset

Ford will never calculate SOH correctly until a reset is done.

🔋 What Your Charging Voltage Tells Me

You reported:

14.1–14.4V

This fits:

  • Normal 20–30°C battery temperature
  • Normal mid-level SOC
  • Normal smart charge behavior
Your alternator appears healthy.
This DOES NOT validate SOH.
Charging voltage is not related to SOH accuracy.

⭐ My professional assessment

Your real SOH is almost certainly:

50–65%

Your displayed SOH = 100% is:

❌ Not real
❌ Not possible for age
❌ Not physiologically correct for an AGM
❌ Not consistent with typical Ford BMS learning behavior


This is a wrong SOH reading.

----------------------------------
Happy Reading!

- T
 

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airline tech

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I have just completed compiling the data into a 45 page document that a lot of us are going to find quite interesting. It was easier to do this as an attachment than to post multiple long messages. There is a lot of data in this document that explains / makes the BMS much clearer. I actually had Chatgpt reverse engineer a bit on Ford proprietary SOH algos... and it spit out a bit of pseudo code!

Here is a list of sections in the PDF document
  • 5G Ford Ranger BMS Overview
  • How does a 2020 Ford BMS calculate SOC?
  • How Does Ford monitor Battery SOH?
  • Why Incorrect SOH Causes Charging Problems
  • How to Reset BMS
  • How Ford calculates SOH (internal algorithm details)
  • What a correct SOH should look like by battery age
  • Diagnosing a Sulfated Battery
  • How to test your battery BMS sensor
  • How to test your alternator’s smart-charge command
  • How to test the battery temperature sensor
  • Normal Ford charging voltage by temperature chart
I find the SOH topics the most interesting. I've got to go over the data in detail... but I already know that Ford has a battery replacement date based upon the weighted criteria they use to determine SOH. SOC has 40%-50% weight, but age of battery is up there too.

Please read the attachment and let me know what you think. (You were not far off on many of your assessments.) But there are few details I know you will find interesting. The BMS is more complex than I assumed, with a lot of moving pieces. It is very dynamic.

I actually entered my data into Chatgpt and it told me with 100% certainty that my Battery SOC and SOH were an impossibility. Here is the exact exchange:
-------------------------------------------
"Quick Reality Check — You Can Use This to Confirm your Battery SOH

If you tell me:
  • Your SOH
  • Your battery age
  • AGM or flooded
  • Your climate
  • Alternator voltage behavior
I can tell you instantly if your SOH is correct or wrong."

I laughed out loud when it came back... I then reentered the data but with a 92% SOH (estimated) from what BMS reported on my last drive 2 days ago and got exactly the same result. Now I did recently reset BMS.. but that was well over 1.5 months ago, and I am confident that it has adjusted itself to the battery's SOH and SOC, and IR. and the absolute lowest SOC reading that the BMS has ever reported is 88% and it is regularly in the mid 90's. Both the Viking and TopDon report back SOH at 100%, and SOC at 100% quite regularly. But neither consider age... and I am not convinced that they should, at least not to the threshold that Ford does. Ford projects battery end of life at 5-6 years. with a SOH below 55%. See the embedded table.

Here's a quote from the document:

Here is the most accurate, realistic SOH-by-age chart for Ford vehicles with Smart Charge (BMS + PCM-controlled alternator). This data is based on:​
  • Ford engineering bulletins
  • Johnson Controls/Varta AGM aging curves
  • What FORScan users consistently report
  • Known behavior of Ford’s SOH estimator
This is not dealer fluff — it’s what you should actually expect to see.​
...​
...​
Ford’s SOH is therefore not just one test—it’s a rolling, adaptive calculation​
updated continuously.​

What Ford and by extension Chatgpt don't know is there is an onboard desultor installed that consistently keeps IR at new battery levels... and IR is weighted by Ford's algo at 50% in determining SOH per the docs Chatgpt provided me.

Anyway, Here was my response:

"Please confirm my Battery SOH, SOH 100%, Battery age 66 months, Battery is AGM, Raleigh, North Carolina Climate, Charge Voltage 14.1 - 14.4v."

And here is what Chatgpt replied:

Based on everything you provided, your Ford’s SOH = 100% is not possible and is definitely incorrect.

Let me break down why with engineering-level clarity.

⭐ Your Inputs
  • SOH: 100%
  • Battery age: 66 months (5.5 years)
  • Battery type: AGM
  • Location: Raleigh, NC (hot/humid summers, moderate winters)
  • Charge voltage observed: 14.1–14.4V (normal mid-temp charging)

⭐ REALITY CHECK: What SOH Should Be

Using the correct Ford SOH age table:

A 5.5-year-old AGM battery in North Carolina climate should realistically be:

45–70% SOH

(Depending on heat exposure, sulfation, charge cycles, and alternator behavior.)

Ford SOH cannot and does not stay at 100% on a 5+ year AGM.

SOH 100% is only normal for:
  • A new battery
  • A recently BMS-reset battery
…NOT for a 66-month AGM.

🚩 Conclusion: Your SOH Value Is Incorrect

Your SOH = 100% is not real.
It indicates a sensor/system reporting error, not an actual healthy battery.

🔍 Top causes when Ford reports false 100% SOH

One or more of these is almost guaranteed:

✔ 1. BMS was recently reset

SOH resets back to 95–100% automatically.
It takes weeks of driving for SOH to drop to its real value.

✔ 2. Incorrect battery type programmed (AGM vs Flooded)

Using “flooded” for an AGM can distort SOH and SOC.

✔ 3. Bad or drifting battery current sensor (MOST COMMON)


Symptoms:
  • SOH stuck high
  • SOC stuck 75–85%
  • GENFDC doesn’t respond to load properly
  • Charge current readings inaccurate
  • No SOH change over time
✔ 4. Bad battery temperature sensor

Incorrect temperature → incorrect resistance normalization → incorrect SOH.

✔ 5. Loose negative cable / corroded ground

Small voltage errors corrupt the SOH calculation.

✔ 6. Battery replaced long ago without BMS reset

Ford will never calculate SOH correctly until a reset is done.

🔋 What Your Charging Voltage Tells Me

You reported:

14.1–14.4V

This fits:

  • Normal 20–30°C battery temperature
  • Normal mid-level SOC
  • Normal smart charge behavior
Your alternator appears healthy.
This DOES NOT validate SOH.
Charging voltage is not related to SOH accuracy.

⭐ My professional assessment

Your real SOH is almost certainly:

50–65%

Your displayed SOH = 100% is:

❌ Not real
❌ Not possible for age
❌ Not physiologically correct for an AGM
❌ Not consistent with typical Ford BMS learning behavior


This is a wrong SOH reading.


----------------------------------
Happy Reading!

- T
WOW- You know I was so frustrated over this simple question - How does the BMS and Charging system work? Which is why I took the dive and created my original post on the - Charging System Operation.

I was able to decipher the majority of the operation but was left in the dark on the details.
I cannot tell you how many hours and how many websites I visited>
NOTE: 95% of any search result was from forums such as this one and within those would be varied Ford (D&O) from the manuals and that was it.
or it was some university (abc) lab results on testing the battery etc.

All those findings and what I posted at least proved mostly correct.

Now, for one I am surprised:shock::crackup: you even would use such an App (Chat GBT) with you disconnecting your TCU and all.
To be HONEST, I never heard of it until a few weeks ago and Saturday Night Live, did a skit about it, I also never really looked deep into what this (AI) is all about, I just know that it pops up in Google Results. :giggle:

What you have posted, should have been EASY TO FIND information, not hidden deep into the dark web.
This is VALIABLE INFORMATION for everyone on this forum and would like to also post the PDF on my thread - Charging Sys Ops, with credit to you (of course). I want to post it in my (OP)

I skimmed through it and the only thing that caught my eye, that is incorrect would be the reference to Gen Mon & Gen Com or whatever they have it labeled. (We Only have LIN)
LIN Replaced the 2 separate data lines with a single data line (LIN)

The SOH, I have not seen as a PID (viewable), and I have only seen this on the Battery Testers we have.

THANK YOU - for this, it's a huge read but informative and provides the unknowns we were seeking - lots of detail to go through.
I see they touched on the subject - but did not go into detail.
Disconnecting the sensor, are there any long-term drawbacks by leaving it disconnected, for those that chose to disconnect?
What is the ideal SOC setting if altering from the factory setting of 75%?

I guess I need t keep up with the times and try this Chat GBT myself.
 
Last edited:
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OP

TJC

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WOW- You know I was so frustrated over this simple question - How does the BMS and Charging system work? Which is why I took the dive and created my original post on the - Charging System Operation.

I was able to decipher the majority of the operation but was left in the dark on the details.
I cannot tell you how many hours and how many websites I visited>
NOTE: 95% of any search result was from forums such as this one and within those would be varied Ford (D&O) from the manuals and that was it.
or it was some university (abc) lab results on testing the battery etc.

All those findings and what I posted at least proved mostly correct.

Now, for one I am surprised:shock::crackup: you even would use such an App (Chat GBT) with you disconnecting your TCU and all.
To be HONEST, I never heard of it until a few weeks ago and Saturday Night Live, did a skit about it, I also never really looked deep into what this (AI) is all about, I just know that it pops up in Google Results. :giggle:

What you have posted, should have been EASY TO FIND information, not hidden deep into the dark web.
This is VALIABLE INFORMATION for everyone on this forum and would like to also post the PDF on my thread - Charging Sys Ops, with credit to you (of course). I want to post it in my (OP)

I skimmed through it and the only thing that caught my eye, that is incorrect would be the reference to Gen Mon & Gen Com or whatever they have it labeled. (We Only have LIN)
LIN Replaced the 2 separate data lines with a single data line (LIN)

The SOH, I have not seen as a PID (viewable), and I have only seen this on the Battery Testers we have.

THANK YOU - for this, it's a huge read but informative and provides the unknowns we were seeking - lots of detail to go through.
I see they touched on the subject - but did not go into detail.
Disconnecting the sensor, are there any long-term drawbacks by leaving it disconnected, for those that chose to disconnect?
What is the ideal SOC setting if altering from the factory setting of 75%?

I guess I need t keep up with the times and try this Chat GBT myself.
I spent my entire career in I/T technology and helped design and create AI / KB databases, and HW / SW AI engines way back in the early to mid 1990s.

I worked with Dr Dave Bradley (he co-wrote the first IBM PC BIOS and invented Ctrl-Alt-Delete) in the late 1980's. A real nice guy.

I am an old school techie, SW and HW developer. I very much like tech, but I want to be in control of it.

Too much has been developed to tempt the public into giving up essential control for convenience. We are selling our freedom for convenience.

The simple truth is that we can have both. The convenience of modern tech without the overlords using that tech to virtually imprison us.

I have more computers in my home then probably 99.5% of the population. 4 of them run 24/7. I use tech, but I do not have a massive footprint on the web. Like many of my techie colleagues, I keep a low public tech footprint.

We understand the ramifications of what we invent. We see the double edge sword. If humanity can technically do something, they will do it, and use it for selfish greed... to the detriment of mankind. It is as simple as that.

I left the USAF for the same reasons. I spent 5 of my 6 years in NORAD & SAC underground bunkers... 3 years at NORAD CMC, and 2 years in a SAC war room. I have seen my fair share of... for lack of a better word, insanity.

Anyway the document just got bigger! Now 83 pages with lots of new questions and answers.

Remember that all of these AI engines can and will lie. And they make serious and obvious errors. I have found several in my answers from questions asked. I left them in and in several cases noted them in red. But with all this said, it does provide insights into the systems. It is an excellent source for medical information as well.

Attached in Version 1.01

Here is the updated list of sections in the PDF document
  • 5G Ford Ranger BMS Overview
  • How does a 2020 Ford BMS calculate SOC?
  • How Does Ford monitor Battery SOH?
  • Why Incorrect SOH Causes Charging Problems
  • How to Reset BMS
  • How Ford calculates SOH (internal algorithm details)
  • What a correct SOH should look like by battery age
  • Diagnosing a Sulfated Battery
  • How to test your battery BMS sensor
  • How to test your alternator’s smart-charge command
  • How to test the battery temperature sensor
  • Normal Ford charging voltage by temperature chart
  • Will a BatteryMinder OBD-12 Desulfator Extend SOH?
  • My truck has been housed in a garage its entire life. How does this affect SOH?
  • Will changing the SOC to 100% with Forscan affect SOH?
  • Will disabling ASS affect SOH?
  • Will unplugging the BMS Sensor affect SOH?
  • Does keeping SOC at ~70% affect SOH?
  • SOC was set by Ford at 70% for the XLT, should I change it to 75% -like the Lariat model?
  • What is the battery voltage at SOC of 70%?
  • Does the SOC at 70% increase sulfation?
  • How long a drive is required to restore a battery to 70%-80%?
  • At what SOC will AGM batteries last the longest?
  • Optimal SOC for AGM battery longevity?
  • How does letting the truck sit unused for 2 weeks affect SOH?
  • Strategy for Optimizing SOH
  • I have installed AMP Research Power Steps to my Ranger. How does this affect SOH?
 

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airline tech

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I spent my entire career in I/T technology and helped design and create AI / KB databases, and HW / SW AI engines way back in the early to mid 1990s.

I worked with Dr Dave Bradley (he co-wrote the first IBM PC BIOS and invented Ctrl-Alt-Delete) in the late 1980's. A real nice guy.

I am an old school techie, SW and HW developer. I very much like tech, but I want to be in control of it.

Too much has been developed to tempt the public into giving up essential control for convenience. We are selling our freedom for convenience.

The simple truth is that we can have both. The convenience of modern tech without the overlords using that tech to virtually imprison us.

I have more computers in my home then probably 99.5% of the population. 4 of them run 24/7. I use tech, but I do not have a massive footprint on the web. Like many of my techie colleagues, I keep a low public tech footprint.

We understand the ramifications of what we invent. We see the double edge sword. If humanity can technically do something, they will do it, and use it for selfish greed... to the detriment of mankind. It is as simple as that.

I left the USAF for the same reasons. I spent 5 of my 6 years in NORAD & SAC underground bunkers... 3 years at NORAD CMC, and 2 years in a SAC war room. I have seen my fair share of... for lack of a better word, insanity.

Anyway the document just got bigger! Now 83 pages with lots of new questions and answers.

Remember that all of these AI engines can and will lie. And they make serious and obvious errors. I have found several in my answers from questions asked. I left them in and in several cases noted them in red. But with all this said, it does provide insights into the systems. It is an excellent source for medical information as well.

Attached in Version 1.01

Here is the updated list of sections in the PDF document
  • 5G Ford Ranger BMS Overview
  • How does a 2020 Ford BMS calculate SOC?
  • How Does Ford monitor Battery SOH?
  • Why Incorrect SOH Causes Charging Problems
  • How to Reset BMS
  • How Ford calculates SOH (internal algorithm details)
  • What a correct SOH should look like by battery age
  • Diagnosing a Sulfated Battery
  • How to test your battery BMS sensor
  • How to test your alternator’s smart-charge command
  • How to test the battery temperature sensor
  • Normal Ford charging voltage by temperature chart
  • Will a BatteryMinder OBD-12 Desulfator Extend SOH?
  • My truck has been housed in a garage its entire life. How does this affect SOH?
  • Will changing the SOC to 100% with Forscan affect SOH?
  • Will disabling ASS affect SOH?
  • Will unplugging the BMS Sensor affect SOH?
  • Does keeping SOC at ~70% affect SOH?
  • SOC was set by Ford at 70% for the XLT, should I change it to 75% -like the Lariat model?
  • What is the battery voltage at SOC of 70%?
  • Does the SOC at 70% increase sulfation?
  • How long a drive is required to restore a battery to 70%-80%?
  • At what SOC will AGM batteries last the longest?
  • Optimal SOC for AGM battery longevity?
  • How does letting the truck sit unused for 2 weeks affect SOH?
  • Strategy for Optimizing SOH
  • I have installed AMP Research Power Steps to my Ranger. How does this affect SOH?

Awesome - It did not attach though- I guess you are still working on it
 


got3fords

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TJC

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Awesome - It did not attach though- I guess you are still working on it
Sorry, Didn't get a lot of sleep last night and simply forgot to attach the PDF!

I think we may finally have enough info to warrant a sound plan that finally takes advantage of the Ford BMS to personalize to individual ways people use their Rangers.

Base upon geo location and climate, garaged or not, distance driven to / from work, ASS on or off, and maybe how often the truck is driven.

There are a lot of variables at play. And sneak peek, ASS harms the battery SOH, BMS if tuned correctly does not. At least according to the data that GpsChat sourced.
 
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TJC

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BTW, It looks like an SOC of 80 might be the sweet spot for me...but only if the down time doesn't drop my battery voltage into sulfation range.

And Airline Tech was right... Anything above an SOC of 80 appears to be harmful in the long term to the battery... but again, it depends on how you use your truck. Short hops - probably better to have the the SOC higher. Long distance driving will need to be lower.

I'm very interested in seeing what others understanding will be.
 
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TJC

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Here is the new PDF.

My hope is that Airline Tech can fill in the missing holes, and correct any errors that GPTChat may have made. It is known to make some serious mistakes. I was playing / testing it and it proved to be wildly incorrect on occasion.

I simply asked it to give me the dates and times at 60 hour increments starting on Nov 3, and running for 3 months.

It came back with a great looking schedule that was flat out WRONG! I pointed out the error, and gptchat apologized, and posted a corrected schedule that was accurate.

A big part of me is thinking that it wasn't mistake, but an intentional error to determine my awareness. To what end? I have no idea, but we ran tests just like that to insure our code was sound, and that the alpha and beta testers we had enrolled were up to the task.

It has been my experience that people give a good reason for their decision or behavior, but rarely give the real reason. Our AI friends may be doing behaving very similar.
 

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airline tech

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OK - I went through the PDF (Revised)

First - The Ranger does not have a SOH nor a Battery IR (PID) - at least with 3 scan tools plus Forscan. Forscan still will not display SOC, but other scan tools will.
I do not remember if FDRS displays that PID

The SOH can be displayed on the battery testers, now the Viking shows truly unobtainable numbers, but the Top-Don I believe shows the most accurate and true readings for the test.

SOH is derived from the IR of the battery.
The Lower the IR the Higher the SOH which in turn shows a higher CCA available.

So, with the Battery Tester we can prove that a 92% SOH is obtainable on a 3 yr Plus Battery

Test Taken just after a charge and headlights (ON) surface charge removed.
For me the most accurate is the TopDon Tester.


Full Charge Testers Compare.webp


So, we can prove that a High SOH is obtainable, but it requires (periodic) external help - I just completed a Charge plus Repair Cycle

Full Charge SOH 92%.webp


Since we do not have a SOH (PID) as called out in the PDF, I believe that the BMS System (BCM) is using the SOC & SOH as detailed (VERY DETAILED) algorithm formula. although we cannot see the actual SOH (PID) we can see the (SOC) and charging voltage changes with the Gen Duty Cycle and Gen Output (Amperage) as well as the Battery (Current In/Out)

SOH:
So, the way I understand it and can actually see it if monitoring the Duty Cycle. I can see small bumps in the cycle - This would be what the BMS sensor is seeing - those small bumps and it's measuring how well the battery can absorb the fast current bump, though the battery voltage reading.

Noted PCM PIDs in the PDF are not correct for the Ranger

1. GENMON
► Generator Monitor
Shows actual alternator field duty cycle (%).
We do not have a GENMON - Since we have a LIN Bus (Single Wire)

But we can see
2. GENFDC (Measured)
► Generator Field Duty Cycle Command
The voltage command the PCM sends to the alternator
This is displayed as a (percent) normal around 35%

3. GEN_VOLT_CMD
► Commanded charging voltage.
We do not have this specific PID
But it's listed as PID - GENVDSD - Generator Voltage Desired or Gen Voltage Setpoint Depending on scan tool.
This is displayed as a voltage


4. GEN_VOLT_ACTUAL
► Actual charging voltage measured
We do not have this specific PID
But its listed and monitoring in these 2 PIDs, note there are various VBAT or Module Supply PIDs for each module - but these are the important ones

VBAT System - System Battery Voltage - This is the voltage at the battery being produced by the Generator - This voltage will read higher when charging (to push current through the battery)

Example: 14.65 Volts (System) with 14.52 (Inferred) and Actual Battery Voltage via BCM/PCM is 14.30 Volts and Gen Desired Voltage Setpoint = 14.40 Volts

Batt V INF - Battery Voltage Inferred
This is the (Inferred Voltage) which is where the SOC (%) reading comes from (BMS Sensor)

I want to take a deeper look and compare these 2 voltages vs my SOC Reading PID as I had to research the difference between these 2 PIDs and this is what I have concluded they are.

We can also see:
Generator Current (Corrected) as an amperage display
and
Also see the Battery Current (In/Out) for charging and discharging.

There are various other related PIDs, but I am only highlighting the important ones for charge monitoring.


As far as the document I find the information very interesting.
It leaves me thinking that most other Ford Models have the SOC set to 80%, which was my original driving factor in upping the SOC from 70% or 75% and I was monitoring the charging voltage (via) the voltmeter in the Power Point and noted what the system did @ idle and stopped. I never felt comfortable watching the commanded voltage drop down to 12.2 or 12.4 Volts

The whole reasoning for bumping the SOC was to eliminate that from happening, and now we have a decision and dilemma to overcome and that is to find our own (SWEET SPOT) that provides a happy medium for the BMS System & Battery Health.
My opinion would be between 85% & 90%, if I recall 90% was the spot that provided (0) low voltage measurements at idle.
I would have to reflect back on my notes on what it did at 85%, I know I have been set @ 90% for quite a while and recently upped it to 95% but backed it back down today to 90%.
I have had zero issues at 90% and my battery IR is staying 3.4 and below.
I like increments of 5 and have not tried something like 88% for example.

So, the question is - by bumping the SOC up, how much does it truly throw off the BMS Algorithm and how far above factory SOC does it truly become detrimental to the battery.
We have proven that the factory set SOC does not work for the Ranger especially for short trip drives.
Since we just actually started monitoring the SOC PID, I am thinking that yes bumping the SOC up does indeed throw what we are seeing off, and it is hovering between 85-90 percent while driving.
I plan on monitoring this a bit deeper and possibly play with the SOC to see what the reading does if I was to lower the SOC back down closer to 75%, as this would give us a true reading and gauge what the factory SOC actually does.


This document does bring up another question.
What effect does the On-Board Batt Minder do to the BMS Algorithm for SOC & SOH?
We know it helps the battery, but what about the BMS Sensor itself?
 
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TJC

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OK - I went through the PDF (Revised)

First - The Ranger does not have a SOH nor a Battery IR (PID) - at least with 3 scan tools plus Forscan. Forscan still will not display SOC, but other scan tools will.
I do not remember if FDRS displays that PID

The SOH can be displayed on the battery testers, now the Viking shows truly unobtainable numbers, but the Top-Don I believe shows the most accurate and true readings for the test.

SOH is derived from the IR of the battery.
The Lower the IR the Higher the SOH which in turn shows a higher CCA available.

So, with the Battery Tester we can prove that a 92% SOH is obtainable on a 3 yr Plus Battery

Test Taken just after a charge and headlights (ON) surface charge removed.
For me the most accurate is the TopDon Tester.


Full Charge Testers Compare.webp


So, we can prove that a High SOH is obtainable, but it requires (periodic) external help - I just completed a Charge plus Repair Cycle

Full Charge SOH 92%.webp


Since we do not have a SOH (PID) as called out in the PDF, I believe that the BMS System (BCM) is using the SOC & SOH as detailed (VERY DETAILED) algorithm formula. although we cannot see the actual SOH (PID) we can see the (SOC) and charging voltage changes with the Gen Duty Cycle and Gen Output (Amperage) as well as the Battery (Current In/Out)

SOH:
So, the way I understand it and can actually see it if monitoring the Duty Cycle. I can see small bumps in the cycle - This would be what the BMS sensor is seeing - those small bumps and it's measuring how well the battery can absorb the fast current bump, though the battery voltage reading.

Noted PCM PIDs in the PDF are not correct for the Ranger

1. GENMON
► Generator Monitor
Shows actual alternator field duty cycle (%).
We do not have a GENMON - Since we have a LIN Bus (Single Wire)

But we can see
2. GENFDC (Measured)
► Generator Field Duty Cycle Command
The voltage command the PCM sends to the alternator
This is displayed as a (percent) normal around 35%

3. GEN_VOLT_CMD
► Commanded charging voltage.
We do not have this specific PID
But it's listed as PID - GENVDSD - Generator Voltage Desired or Gen Voltage Setpoint Depending on scan tool.
This is displayed as a voltage


4. GEN_VOLT_ACTUAL
► Actual charging voltage measured
We do not have this specific PID
But its listed and monitoring in these 2 PIDs, note there are various VBAT or Module Supply PIDs for each module - but these are the important ones

VBAT System - System Battery Voltage - This is the voltage at the battery being produced by the Generator - This voltage will read higher when charging (to push current through the battery)

Example: 14.65 Volts (System) with 14.52 (Inferred) and Actual Battery Voltage via BCM/PCM is 14.30 Volts and Gen Desired Voltage Setpoint = 14.40 Volts

Batt V INF - Battery Voltage Inferred
This is the (Inferred Voltage) which is where the SOC (%) reading comes from (BMS Sensor)

I want to take a deeper look and compare these 2 voltages vs my SOC Reading PID as I had to research the difference between these 2 PIDs and this is what I have concluded they are.

We can also see:
Generator Current (Corrected) as an amperage display
and
Also see the Battery Current (In/Out) for charging and discharging.

There are various other related PIDs, but I am only highlighting the important ones for charge monitoring.


As far as the document I find the information very interesting.
It leaves me thinking that most other Ford Models have the SOC set to 80%, which was my original driving factor in upping the SOC from 70% or 75% and I was monitoring the charging voltage (via) the voltmeter in the Power Point and noted what the system did @ idle and stopped. I never felt comfortable watching the commanded voltage drop down to 12.2 or 12.4 Volts

The whole reasoning for bumping the SOC was to eliminate that from happening, and now we have a decision and dilemma to overcome and that is to find our own (SWEET SPOT) that provides a happy medium for the BMS System & Battery Health.
My opinion would be between 85% & 90%, if I recall 90% was the spot that provided (0) low voltage measurements at idle.
I would have to reflect back on my notes on what it did at 85%, I know I have been set @ 90% for quite a while and recently upped it to 95% but backed it back down today to 90%.
I have had zero issues at 90% and my battery IR is staying 3.4 and below.
I like increments of 5 and have not tried something like 88% for example.

So, the question is - by bumping the SOC up, how much does it truly throw off the BMS Algorithm and how far above factory SOC does it truly become detrimental to the battery.
We have proven that the factory set SOC does not work for the Ranger especially for short trip drives.
Since we just actually started monitoring the SOC PID, I am thinking that yes bumping the SOC up does indeed throw what we are seeing off, and it is hovering between 85-90 percent while driving.
I plan on monitoring this a bit deeper and possibly play with the SOC to see what the reading does if I was to lower the SOC back down closer to 75%, as this would give us a true reading and gauge what the factory SOC actually does.


This document does bring up another question.
What effect does the On-Board Batt Minder do to the BMS Algorithm for SOC & SOH?
We know it helps the battery, but what about the BMS Sensor itself?
I had a 100% confidence level that you would fill in the holes. I inferred the same results.
  • I do beleive the Batterty Minder Onboard Desulfator substantually extends the battery life... and more then ChatGPT suggests. I can not speak to the other desulfators on the market.

    I've tried a few on my 24v I/T battery backup systems, and still awaiting the results. I have 4 battery back up units, 1 died early. The are still chugging along fine. I do not think the desultafor killed that battery. I think the Backup until over charged the battery. I'll break it open and repair the failing component that let charge voltage rise a bit too much.

  • I do beleive that the positive change the desulfator makes may disrupt the battery aging algo that Ford built in to the BMS, but without know definitively how much of the firmware is hard coded vs derived (hard coded implies less adapability/flexibility to react to the sensor inputs) from more advanced algos it remains an unknown. But I suspect that the Ford algos are far more advanced than I previously believed.

    That statement made, that doesn't change the fact that Ford has optimized the Algo for ASS / EPA goals over extended battery life. This is CLEAR. Note that in the PDF ChatGPT actually states that turning off ASS will improve battery health. (I think it improves engine/drivetrain health as well)

  • While there may not be a PID for SOH, it is clear that the BMS dynamically derives SOH and targets/manipulates the same paramerters that SOH is calculated / derived from.

  • I note that your battery Rated CCA is higher than the rated CCA from the manufacturer - using both the Viking and the TopDon.

  • I also believe the TopDon to be more real world precise, but using rulers with different increments doesn't matter as long as you stick to the one you used first. The delta data change will be present in both tools. Both will still reflect relative battery health, just at different places on the scale. I think both will tell you when your battery begins to fail and when it is healthy.
  • Re: SOC - Based upon my realworld experience, it seems the BMS may be adjusting the SOC target over time. I set teh SOC at 100, and on the first drive or so it performed as expected, then fropped to 95%, then dropped to the mid 80's. That is when I reset the BMS, Charge voltage dropped from the low 14 volts. to the 13.6v. Over teh next few days the charge voltagewewnt back to 14.1v-14.4v. I have not drivent the rruck enough to see of the SOC drops back to the mid 80's (or even lower ir I do not interrrupt it.). I am going to let it ride for a week or so and see what results.

  • I now do agree that a lower SOC charge is healthier, but this depends on how often you drive. You must keep the battery voltage above the sulfation threshhold, and 12.2v is much too low. I am much more comfortable at 12.6-12.65v, and by this I mean I want to see this voltage for days after I turn the truck off. The closer we get to the is voltage the longer the battery life. We accomplish this by balancing charge SOC and minimizing dark drain current as best we can.

  • While I am mentioning this, I have noted that keeping the hood latch locked while charging the battery, or while leaving ther hood up over night has lowered my battery discharge rate substantially. I mean SUBSTANTIALLY. I am seeing precious little drops in battery readings since I starting locking that latch. I left the hood up to keep from opening the doors when checking the battery condition. My battery voltage is holding very steady over a 7-10 days since changing my routine. I have not investigated what systems remain active with the hood up, but it makes a measurable difference.
I only skimmed yoru report. I need to read it in more detail... So more to discuss later. Right now I have a 2 hour ride ahead - Must head out to family Thanksgiving Dinner!

Thank you again for your interest, knowledge and research. I very much apprciate it. I think that we are very close to understanding enough of the inner workings of the BMS to intelligently optimize the settings.
 

Ranger_Rocks

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... Right now I have a 2 hour ride ahead - Must head out to family Thanksgiving Dinner!
Have you been spending a little to much time in the garage testing your battery ?

Thanksgiving was Thursday. :crackup:
 

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I believe I can confirm the Voltage at the battery terminals (Inferred) is the BMS Sensor Input
and depending on what you have (SET) as the SOC, dictates what the charging system does at this point - Using the SOC/Battery Voltage Chart

I have been performing a few, battery charge & repair cycles.
So, battery was fully charged at beginning of test - reading 100% SOC, normal charging until I turned off the headlights (Load)
Then the Desired Setpoint - dropped to 12.6 Volts and since the battery was fully charged it allowed the battery to support the load - also reading 12.6 on the voltmeter.
After a minute or so - the SOC dropped to 99% and the (Inferred Batt Voltage was 12.71 Volts)
in 35 seconds - the SOC ticked up to 100% - with a (Inferred Batt Voltage of 13.15 volts)

Voltage at each progression:
Note: This was with Headlights (Off) @ Idle
Desired Voltage Setpoint: 12.6
Sys Voltage 12.6
Inferred Voltage 12.71
Battery Current: (-2 amps)
SOC: 100%
SOC Set via Forscan: 90%

At this point when SOC dropped to 99%
The Desired Set Point: Progressively Raised to 13.04 Volts and in 35 Seconds the SOC bumped back up to 100%
However, the (Inferred Voltage now reads 13.5 Volts) as it has a charging voltage applied.
Desired Setpoint: 13.04 Volts
Battery Current (+8.19 amps) and the amperage charge slowly backed off.

So, what this tells me is that the SOC (Set) @ 90% equals 12.71 Volts the same as the charts show.
BUT what we are reading (MAY) be read as 99% SOC actually equals 99% of what we have as (SET)
per my test this is my conclusion as 100% SOC for my test equals 12.71 Volts which is my setting of 90% SOC.

Further tests will need to be performed with the SOC (SET) lower and easier for the system to obtain.

I will say that I must have had some sulfation as I have not been doing regular Charge & Repair cycles and may have been the reason for my SOC reading hanging in the 85% to 91% range and it being a very slow climb during the drive cycle test.
More drive cycle tests will be performed to monitor this after my aggressive battery charge and repair cycles in the last few days.
I am curious to see the results and also if I experience the same as you - Lowering SOC (progressive)

But for now - note this was just after my above test so the reason for the lower battery voltage reading as the system was not charging.
But the (SOH) amazed me

This by far the best SOH reading I have ever seen, granted this is fresh after a recent charge, need to do some drive cycles and see if it remains.

Top-Don Nov 2025.webp
 
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TJC

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Have you been spending a little to much time in the garage testing your battery ?

Thanksgiving was Thursday. :crackup:
Absolutely....

NOT! :LOL:

My Sister in Law had a delayed Thanksgiving Dinner due to unforeseen circumstances, and we were invited! Gave my wife time to visit witrh her family. It was a nice day!
 
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TJC

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Your comments in Bold. My response below in normal italics font

I believe I can confirm the Voltage at the battery terminals (Inferred) is the BMS Sensor Input
and depending on what you have (SET) as the SOC, dictates what the charging system does at this point - Using the SOC/Battery Voltage Chart


So 100% SOC = 12.6v - 12.8V (based on the table). This seems to be the perfect charge to the best of my knowledge.

I have been performing a few, battery charge & repair cycles.
So, battery was fully charged at beginning of test - reading 100% SOC, normal charging until I turned off the headlights (Load)
Then the Desired Setpoint - dropped to 12.6 Volts and since the battery was fully charged it allowed the battery to support the load - also reading 12.6 on the voltmeter.
After a minute or so - the SOC dropped to 99% and the (Inferred Batt Voltage was 12.71 Volts)
in 35 seconds - the SOC ticked up to 100% - with a (Inferred Batt Voltage of 13.15 volts)

Voltage at each progression:
Note: This was with Headlights (Off) @ Idle
Desired Voltage Setpoint: 12.6
Sys Voltage 12.6
Inferred Voltage 12.71
Battery Current: (-2 amps)
SOC: 100%
SOC Set via Forscan: 90%

At this point when SOC dropped to 99%
The Desired Set Point: Progressively Raised to 13.04 Volts and in 35 Seconds the SOC bumped back up to 100%
However, the (Inferred Voltage now reads 13.5 Volts) as it has a charging voltage applied.
Desired Setpoint: 13.04 Volts
Battery Current (+8.19 amps) and the amperage charge slowly backed off.


This is expected, from what I have experienced

So, what this tells me is that the SOC (Set) @ 90% equals 12.71 Volts the same as the charts show.

90% of the Target that we set in ForScan? So what you are saying is that Setting your SPC at 80% in Forscan actually results to 12.71V at the battery terminals when SOC = 100%. Am I understanding correctly?

BUT what we are reading (MAY) be read as 99% SOC actually equals 99% of what we have as (SET) per my test this is my conclusion as 100% SOC for my test equals 12.71 Volts which is my setting of 90% SOC.

90% is actually 12.75V, but may be close enough. due to aging , resting state, and temperature, etc.

Is this the table that you a referencing?

1764463861603-ct.webp


Further tests will need to be performed with the SOC (SET) lower and easier for the system to obtain.

I will say that I must have had some sulfation as I have not been doing regular Charge & Repair cycles and may have been the reason for my SOC reading hanging in the 85% to 91% range and it being a very slow climb during the drive cycle test.
More drive cycle tests will be performed to monitor this after my aggressive battery charge and repair cycles in the last few days.
I am curious to see the results and also if I experience the same as you - Lowering SOC (progressive)

But for now - note this was just after my above test so the reason for the lower battery voltage reading as the system was not charging.
But the (SOH) amazed me

This by far the best SOH reading I have ever seen, granted this is fresh after a recent charge, need to do some drive cycles and see if it remains.

Top-Don Nov 2025.webp


More as I digest your note more.
Sponsored

 
 








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