Ford BMS issues, research, testing, and solution results

[Snippy]

Are you trying to do this with the engine running? If so, the battery light will stay out if all is well.

The BMS reset procedure needs to be done with ignition on, engine off. Then you will see the battery light, and it flashing when the procedure is successful.

No the engine is off but ignition is on. I don’t see a battery icon anywhere on the dash.

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[SilverPigeon]

That'd be bad... can you take a photo of the whole cluster when the ignition is on and the engine is off? Then we can see what you're seeing

 

[Touringsedan]

My setting of 120% is 120*16=1,920 -> 0780 hex.

Why do you have your Battery SOC to 120% or the 0780 hex? just wondering.

 

[FirstFord]

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.

I was so excited that I already ordered the part!

My module arrived this afternoon. I was so excited, you would have thought I was a kid on Christmas morning. I ripped open the package, and my heart sank: the date on the module is 10/26/23. According to @Porpoise Hork 's research, the "improved" modules began being produced "mid-October". So where does that put my build? I don't know. Because I ordered it over the internet rather than getting it from my local dealer, I couldn't check the date prior to ordering. It was a $17.00 (plus shipping) gamble. I thought it was worth the gamble, even if I wind up losing...

 

[SilverPigeon]

Why do you have your Battery SOC to 120% or the 0780 hex? just wondering.

Because of this post: https://www.f150gen14.com/forum/thr...ge-how-to-power-accessories.13862/post-452723 - SOC% has never hit 90% and rarely now drops below 70%. I'm still not happy with how the original BMS is behaving which is why I want to try a new one.

 

[Porpoise Hork]

My module arrived this afternoon. I was so excited, you would have thought I was a kid on Christmas morning. I ripped open the package, and my heart sank: the date on the module is 10/26/23. According to @Porpoise Hork 's research, the "improved" modules began being produced "mid-October". So where does that put my build? I don't know. Because I ordered it over the internet rather than getting it from my local dealer, I couldn't check the date prior to ordering. It was a $17.00 (plus shipping) gamble. I thought it was worth the gamble, even if I wind up losing...

It would most likely be the ML3Z-10C679-B. Ford released the customer service program to replace faulty BMS in early Jan 24 citing the ML3Z-10C679-B as the replacement. This is also about when it started appearing when purchased from places like Tasca with ML3T-10C652-BA stamped on it but a build date a little over two weeks earlier than the one you got.

https://www.f150lightningforum.com/...ings-bms-sensor-replacement.17900/post-361618

Multiple people in that thread along with others later reported that after installing the BMS with similar dates that the SOC behavior was much improved as well as they started receiving OTA updates again. Some others do show the same BMS with build dates with the same coding as 8/5/23 but had seen similar results as the guy in the post I linked.

 

[FirstFord]

It would most likely be the ML3Z-10C679-B. Ford released the customer service program to replace faulty BMS in early Jan 24 citing the ML3Z-10C679-B as the replacement. This is also about when it started appearing when purchased from places like Tasca with ML3T-10C652-BA stamped on it but a build date a little over two weeks earlier than the one you got.

https://www.f150lightningforum.com/...ings-bms-sensor-replacement.17900/post-361618

Multiple people in that thread along with others later reported that after installing the BMS with similar dates that the SOC behavior was much improved as well as they started receiving OTA updates again. Some others do show the same BMS with build dates with the same coding as 8/5/23 but had seen similar results as the guy in the post I linked.

Much thanks, Bret. I feel a little better about it. The real test will be in monitoring its behavior in the upcoming weeks. If this newer BCM winds up being "the answer", then you will have saved my sanity, because nothing was making any sense with my SOC readings!

By the way, this was the first time I used the headlight flash, brake pedal method to reset the BCM (I previously used FORScan). You indicated in your instructions that when successful, the Battery indicator would flash 3 times. When I finished, no "Battery" light flashed, but the "Check Engine" light flashed 3 or 4 times. I assume we are talking about the same thing? (At this point, I don't want to take any chances...)

EDIT: This is my new BCM:

 

[FirstFord]

Whoops! It appears that I may have unintentionally / inadvertently supplied some bad information. For the sake of speed and simplicity, I reasoned that I would compare the ASBUILT values of the original OEM backup to that of a more recent backup, and note the differences. Seemed fair enough.... But now I realize that there were a few assumptions packed in with that thinking.

I keep a spreadsheet "log" of any and all changes made through FORScan, and I record the existing values before the change, as well as the change itself (in effect, it is somewhat of a secondary backup). I reviewed my log, and the values don't jibe with what I posted earlier. I know that OTA updates (obviously) can change ASBUILT values. It appears that somewhere along the way, an OTA changed the original ASBUILT values for the BCM 726-08-02 address (the values that were in my original backup), but prior to my effort to change it. When I went to increase the charge rate in FORScan, I recorded in my log that the values were:
726-08-0200070805A4EB Which is different from what I had in my original backup, thus the conclusion that it was changed by an OTA.
After attempting to increase the charge rate (using the "Easy Mehod"), I apparently went back and noted the new values where the 4 was changed to 0 (A0EB, which was also reflected in a more recent backup). I'm hoping to be able to get the laptop plugged in the next couple of days and reconfirm.

(I feel kind of weird quoting myself, but its just a reference for this post.)

So, I finally got to a point where I could check the currently existing values in FORScan - interesting! (And my education continues!) As a preface, I will state that I am exceedingly aware of the utmost importance to use values that are accurate, so when I make my spreadsheet records, I triple check the values. The values had changed from when I recorded them in my spreadsheet! I again assume that an OTA was the reason. Based on this, I concluded (correctly or not) that any OTA may have far-reaching tentacles that affect other modules that you might not ever even associate with the module that is the target of the update.

So, while I was in there fooling around - and being completely ignorant regarding hexadecimal - played around with entering different values using the so-called "Easy Method", and then went and recorded the ASBUILT values that the changes yielded.

		726-08-02	0007	xxxx	xxxx
"Easy Method" of	Yielded ASBUILT Value:
80%				0805	004B
95%				0805	F03B
96%				0806	004C
98%				0806	206C
100%				0806	408C

 

[Touringsedan]

Because of this post: https://www.f150gen14.com/forum/thr...ge-how-to-power-accessories.13862/post-452723 - SOC% has never hit 90% and rarely now drops below 70%. I'm still not happy with how the original BMS is behaving which is why I want to try a new one.

Thank you. I have added that thread to my read list. I have been reading all the entries in the Forscan thread first and added the BMS ones to that reading list. Thanks for all the hard work and great insight.

 

[ReverendQ]

No incentive except to get a new one for a couple of bucks?

And you are right, in that my Battery Management woes are behind me and have been since swapping the aux AGM for the LFP.

My truck sat for 12 days before I got in it this morning. The static voltage was 12.78V as a result of multiple door opening and tailgate down/up events over those 12 days. The Ford SOC PID said 92% on startup.

By the time I got to the office it was 97% with me running the fan5 procedure for about 20 miles.

I don't think I have a malfunctioning shunt/sensor.
But I still am curious if I will see any changes if I replace it with a new version?

I actually never had issues @Porpoise Hork had but have added PRB and PFM and have approach detection on and realize these sip off, and sometimes drink, off the 12VDC system. These in addition to whatever else the truck is contemplating including OTA updates via WiFi or Cellular, etc.

Between the extra capacity of a 30 mAh LiFePO Auxiliary Battery, and hood solar, I rarely see less than 9X% SOC. About the only time it is much less is when I leave the truck in the street with the dash cameras running and have poor sun light and it's a bit windy. The activity in the causes the cameras to Amp up, the wind causes the alarm to trigger, and no sun means the power consumed is not replenished by the hood solar.

I am not blaming you as much as OP @Porpoise Hork, but I too was curious to understand if it changes anything . So $21 bucks and five minutes later...

 

[Snakebitten]

Wait.
You beat me to actually doing it?

I'm all talk. Apparently.

 

[Porpoise Hork]

I actually never had issues @Porpoise Hork had but have added PRB and PFM and have approach detection on and realize these sip off, and sometimes drink, off the 12VDC system. These in addition to whatever else the truck is contemplating including OTA updates via WiFi or Cellular, etc.

Between the extra capacity of a 30 mAh LiFePO Auxiliary Battery, and hood solar, I rarely see less than 9X% SOC. About the only time it is much less is when I leave the truck in the street with the dash cameras running and have poor sun light and it's a bit windy. The activity in the causes the cameras to Amp up, the wind causes the alarm to trigger, and no sun means the power consumed is not replenished by the hood solar.

I am not blaming you as much as OP @Porpoise Hork, but I too was curious to understand if it changes anything . So $21 bucks and five minutes later...

What is das hood solar that you speak of?

 

[ReverendQ]

What is das hood solar that you speak of?

Post #44 has a link to it and the biggest Aux battery that fits

 

[bgalakazam]

Is this worth it on a 2021-05-19 build date?

had OTA issues, but not battery related. I have a H8 AGM in.

Shipping is more than part

 

[Porpoise Hork]

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.

Is this worth it on a 2021-05-19 build date?

had OTA issues, but not battery related. I have a H8 AGM in.

Shipping is more than part

Best thing to do is monitor the battery SOC levels over time to see if you experience random drops in what is reported vs actual voltages at the battery. Especially if you have the SOC set to anything above Ford's default. If for example you have it set to 95% and it maintains that for extended periods and does not fluctuate then you're prbably good. However if it randomly drops 10-20% overnight but actual voltage of the battery does not reflect this SOC level (like mine did) then replacing the BMS with the latest revision should be considered.

You can use a bluetooth OBD scan tool and app to check the battery SOC reading as reported by the BMS. You can also ise a volt meter or bluetooth battery monitor to see what the resting voltage is of the battery.

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