Ford BMS Battery Monitoring System: How it Works, How to Properly Charge, How to Power Accessories

[scott011422]

Hey Everyone,

Hoping y'all can help me figure out what I need to do here.

I started getting the 12v state of charge low errors a couple weeks ago. I work from home, so most weekdays, my only driving is to and from Starbucks in the morning. Tossed my battery charger on (which is also a maintainer) per the recommendation in the youtube video, but fairly quickly it reported the battery was charged and switched over to maintainer mode and stopped charging. Checked my SOC using OBDII and it only reported ~48%. Performed a BMS reset and now it reports in the 70s but I can't get past 78%. Drove the truck almost all day today and it still only got to 78%. I had hit 80% a few days ago but it quickly went back down and hasn't gotten back since.

Do I need to disconnect the in-cab battery and then charge the under-hood one?
Do I need to do the opposite of above?
Do I need a new battery?
Do I need to get a manual battery charger where I tell it when to stop charging?

I've got an OTA update that won't load because of this (23-PU1009-SS-NS)

Thanks for your advice!

Did you increase your SOC? If not, its 80% by default. So your about as perfect as stock gets.

Charging is always questionable when charging the easy way. The Aux battery till charge much faster than the big 12v under the hood. The smart chargers will often see that and shut down. I cant easy charge with ANY of my cheepos without disconnecting a battery. My Odyssey charger has no problem easy charging with both batteries. If you want to be certain, Disconnect and charge the batteries separately.

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[scott011422]

I have great respect for this point of view.
But I also believe that the OEM has no choice but to set parameters and strategies for a hypothetical use case. Or put another way, they had to choose some estimated range of hours running per day/week, for example.
I do think the original charging strategy was sufficient for a constantly driven truck, but was way too conservative for those on the other end of the spectrum. And I think the forum has well documented the impact and shortcomings.

Having said that, the new charging strategy, at least on my Powerboost, is a fairly dramatic shift. I wouldn't call it a tweak by any means. It's fairly aggressive by comparison.

Which brings up my final point. I agree with you that someone should use some degree of caution if all they are going to do is edit Asbuilt values without monitoring the necessary PIDs to witness the affects of any changes made. I personally do not want 100% SOC, nor would I do anything to assist my truck in aiming for that.

Do you have any screenshots of daily driving on the logger? I'm not really seeing any difference with that battery update. If anything, I notice there will be a random charging event when i'm above the 12.49 threshold. Other than these random events, Everything seems to be about the same.

 

[Snakebitten]

Do you have any screenshots of daily driving on the logger? I'm not really seeing any difference with that battery update. If anything, I notice there will be a random charging event when i'm above the 12.49 threshold. Other than these random events, Everything seems to be about the same.

The Voltage logger is just voltage, so although it is definitely part of the equation, unless you are monitoring the Ford SOC value, and more importantly, the amount of current (amps from the DC/DC converter) being supplied to charge the battery, you couldn't really know what has changed.

But let's say you were only monitoring the Ford SOC value.
It was impossible not to notice how much quicker the SOC increased once the truck was in use. The rate of increase, especially at the beginning of each drive, is much more rapid.

Because I also monitor the PID for amps being provided to the LV battery, it was obvious why the SOC was increasing at a quicker rate.

For nearly 3 years I watched the BMS, as I describe it, trickle charge the battery. I use that term because of the small amount of charging current. The vast majority of the time the truck was providing 1-5 amps of current regardless of whether it was 12.7V, or 13.7V or 14.7V.

That was fine as long as the SOC (Ford's SOC) was 85%, or on long runs maybe even higher. But if the trucks battery was already at a low SOC, regardless of whether it was from an injured-weak battery, or the truck had simply sat a while and parasiticaly been drawn down, or any other reason, the BMS was still stingy with the current.

No longer.
It's like the difference between charging the battery with a Clore Pl2320 set at 20amps vs 2 or 10. The charging voltage might be the same, but the volume of current being supplied is double, or triple.

I took some screenshots and posted in another thread when I had first noticed. It was to show how much more aggressive and how quickly the SOC was climbing now. And remarkably, it was even with the SOC being ABOVE 80%.

Note that at just 2 miles of driving, the SOC has already hit 82%
And amazingly the BMS is throwing 28Amps of charging current at the battery. I was stunned at seeing this. Ford was not using this strategy before.

Just 2 miles later.
SOC is up 2%???
That's not trickle charging.
And at 84% SOC, Ford is still throwing 20amps at it? Not 3 or maaaaybeeee 4?

Halfway home from the office.
Just 12 miles.
88%. I would have feinted a year ago.
9 AMPs still.
What happened at Ford for them to decide to actually charge the battery while I'm driving? It's like I have my 2018 3.5 Ecoboost under the hood now.

 

[PaulGrun]

The Voltage logger is just voltage, so although it is definitely part of the equation, unless you are monitoring the Ford SOC value, and more importantly, the amount of current (amps from the DC/DC converter) being supplied to charge the battery, you couldn't really know what has changed.

But let's say you were only monitoring the Ford SOC value.
It was impossible not to notice how much quicker the SOC increased once the truck was in use. The rate of increase, especially at the beginning of each drive, is much more rapid.

Because I also monitor the PID for amps being provided to the LV battery, it was obvious why the SOC was increasing at a quicker rate.

For nearly 3 years I watched the BMS, as I describe it, trickle charge the battery. I use that term because of the small amount of charging current. The vast majority of the time the truck was providing 1-5 amps of current regardless of whether it was 12.7V, or 13.7V or 14.7V.

That was fine as long as the SOC (Ford's SOC) was 85%, or on long runs maybe even higher. But if the trucks battery was already at a low SOC, regardless of whether it was from an injured-weak battery, or the truck had simply sat a while and parasiticaly been drawn down, or any other reason, the BMS was still stingy with the current.

No longer.
It's like the difference between charging the battery with a Clore Pl2320 set at 20amps vs 2 or 10. The charging voltage might be the same, but the volume of current being supplied is double, or triple.

I took some screenshots and posted in another thread when I had first noticed. It was to show how much more aggressive and how quickly the SOC was climbing now. And remarkably, it was even with the SOC being ABOVE 80%.

Note that at just 2 miles of driving, the SOC has already hit 82%
And amazingly the BMS is throwing 28Amps of charging current at the battery. I was stunned at seeing this. Ford was not using this strategy before.

Just 2 miles later.
SOC is up 2%???
That's not trickle charging.
And at 84% SOC, Ford is still throwing 20amps at it? Not 3 or maaaaybeeee 4?

Halfway home from the office.
Just 12 miles.
88%. I would have feinted a year ago.
9 AMPs still.
What happened at Ford for them to decide to actually charge the battery while I'm driving? It's like I have my 2018 3.5 Ecoboost under the hood now.

So it seems clear that Ford actually solved the problem properly. Good news.

 

[Snakebitten]

So it seems clear that Ford actually solved the problem properly. Good news.

I guess that depends on which problem?

I do think their altered battery charging strategy will help enormously with keeping a "low use" vehicle's battery charged.

I don't think it will solve the problem of having a low quality battery under the hood. If that is indeed true.

Although I bet it would mask the issue of a lesser quality battery? The average fella isn't going to be affected by a lower quality battery as long as that battery is providing the necessary current when it is being required to.

 

[Snakebitten]

I also don't know how to explain the changes in daily parasitic draw on the truck now either.
Is it possible that the update(s) are adjusting more than just the charging strategy.

This is the static voltage log for 13 days of the truck sitting in the barn.
First graph is May 10-16
Second graph is May 16-22

Voltage sat at ~12.5V on day 1
Voltage sat at ~12.4V on day 13

Admittedly the truck sat undisturbed by a key fob or a door opening, but I still have no explanation for a truck not being in battery protection mode (deep sleep) yet losing only a 1/10th of a volt in 2 weeks.

So much about this truck is different than when it came off the assembly line. And other than the tires and some suspension mods, it's 100% software that's behind it.

 

[SilverPigeon]

After sitting on NOCO 10 for days and nights (mostly weekend driven), SOC is in the 50's%. Target SOC set to 103%, all I do is long drives > 30 mins. Cannot get the SOC over 65%, at which time OBD Fusion reports the Battery Current PID as 0A (nothing going in). Has had BMS resets. Spent 60 bucks on a battery tester from amazon which arrives in a day or two. No software updates yet, but I'm betting the factory H6 is toast, maybe a completely dead cell. Will keep you posted

 

[PaulGrun]

After sitting on NOCO 10 for days and nights (mostly weekend driven), SOC is in the 50's%. Target SOC set to 103%, all I do is long drives > 30 mins. Cannot get the SOC over 65%, at which time OBD Fusion reports the Battery Current PID as 0A (nothing going in). Has had BMS resets. Spent 60 bucks on a battery tester from amazon which arrives in a day or two. No software updates yet, but I'm betting the factory H6 is toast, maybe a completely dead cell. Will keep you posted

Without discounting the possibility that your H6 is indeed shot, you might try verifying that you have all OTA updates and restore your SOC to 80%. You may well find that your problems are solved.
In reading through the thread, my theory is that folks have been monkeying around with SOC threshold to no avail since the problem lay deeper in the charging strategy being used. According to @Snakebitten, there’s a very good chance that Ford solved the charging strategy problem. I believe it.

 

[SilverPigeon]

Without discounting the possibility that your H6 is indeed shot, you might try verifying that you have all OTA updates and restore your SOC to 80%. You may well find that your problems are solved.
In reading through the thread, my theory is that folks have been monkeying around with SOC threshold to no avail since the problem lay deeper in the charging strategy being used. According to @Snakebitten, there’s a very good chance that Ford solved the charging strategy problem. I believe it.

Indeed Paul, but no OTA out across the ditch here (long story previously covered), so if the dealer doesn't update everything via FDRS (which they promised me) then I'll be getting a 40A supply and doing them myself. I've had no cranks, shutdowns, NOCO 10 charge errors (battery faulty/cannot charge) so I'll be quite taken aback if the battery test good... we'll see

P.S. The truck started at default 80% target and was having these problems; I moved it to 103% to force it to stay in conventional charging while driving (verified by PID) and that's where I'm hitting the 60's% 0A wall.

 

[SilverPigeon]

Well, knock me down with a feather and I'm glad I don't bet money; the H6 is fine, despite sitting 9 months between factory and I.

I've detailed everything I did in another post because I don't want to clog this one; if you have an H6 battery, I think it's worth your while to read

 

[scott011422]

But let's say you were only monitoring the Ford SOC value.
It was impossible not to notice how much quicker the SOC increased once the truck was in use. The rate of increase, especially at the beginning of each drive, is much more rapid.

For nearly 3 years I watched the BMS, as I describe it, trickle charge the battery. I use that term because of the small amount of charging current. The vast majority of the time the truck was providing 1-5 amps of current regardless of whether it was 12.7V, or 13.7V or 14.7V.

Note that at just 2 miles of driving, the SOC has already hit 82%
And amazingly the BMS is throwing 28Amps of charging current at the battery. I was stunned at seeing this. Ford was not using this strategy before.

So overall, Still don't see much in changes. It still charges per key cycle only, and even with lower SOC, isn't charging every cycle. Still doing that low SOC or Voltage threshold.

What I did just notice yesterday is, I deep cleaned my interior on Monday leaving the battery at 12.1v. After driving 30m to work yesterday the battery recovered a whole .52v to 12.63v! That Dc/Dc converter was REALLY getting after it!

So yeah, Definite change there!

 

[scott011422]

There are three BMS config in BCM, I recommend setting to

TargetSOC_Cfg: 726-08-02 xxxx xx07 80--
0780=120%, the value from 2020+ Police Interceptor Utility with AGM H8 and 2021+ F-150 Police

RegenFunctionActive_Cfg: 726-07-02 xxxx x0xx xx--
RegenFunctionActive means Ford Smart Regenerative Charging, in PIU it was 0=disabled

RefreshFunctionActive_Cfg: 726-07-01 xxxx x1xx xx--
RefreshFunctionActive means SRC battery refresh phase, it was 1=enabled by default

Edit:
about SRC
https://www.motor-talk.de/forum/aktion/Attachment.html?attachmentId=749293

and see attached .pdf from Ford

I did this to my PowerBoost Sunday. it does NOT look like it works on the PowerBoost. My trip in this morning was my first one where my starting voltage was over the 12.5 threshold at 12.55v. 30m drive later I discharged to 12.54 after giving the truck a few hours to settle.

My starting settings were:

726-08-02 0007 0806 206C
726-07-02 0028 0101 0161
726-07-01 0200 0100 3068

I set to the following:

726-08-02 0007 0807 806C
726-07-02 0028 0001 0161
726-07-01 0200 0100 3068


Unless I missed something?

 

[Hyins]

I did this to my PowerBoost Sunday. it does NOT look like it works on the PowerBoost. My trip in this morning was my first one where my starting voltage was over the 12.5 threshold at 12.55v. 30m drive later I discharged to 12.54 after giving the truck a few hours to settle.

My starting settings were:

726-08-02 0007 0806 206C
726-07-02 0028 0101 0161
726-07-01 0200 0100 3068

I set to the following:

726-08-02 0007 0807 806C
726-07-02 0028 0001 0161
726-07-01 0200 0100 3068


Unless I missed something?

Use some OBD tool to monitor the BCM PID BAT_CHRG_Mode (Battery charging mode), the PID should display Conventional Charging.

 

[MLCRNMedicTX]

An update on my situation after changing to Hyins recommendations…All is running well. No issues. Truck charges up completely as evidenced by watching the batt charge PID. It starts around 8-10 amps and decreases to 1-2 each drive. I attached a few pics to show what voltage it charges to and then the steady state overnight. I just returned home and the truck has been sitting for around 10 min or so. I am pleased so far…ymmv.

 

[MLCRNMedicTX]

These were a few days ago…

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