Ford BMS issues, research, testing, and solution results

[Davexxxx]

Seems to be hit/miss from the results others have gotten. For some like myself who's primary issue was random overnight large SOC drops, the updated BMS seems to be a solid fix. For others especially the non PB owners, Ford's anemic charging strategy rears its gnarled head and looks to be a major contributor to those trucks not being able to maintain the set SOC.

I mean I get why Ford is trying to squeeze as high an average mpg across their fleet as possible so they can hit EPA standards to reduce the fines as much as possible for missing the mark. The thing is none of the other car brands on the market appear to have as much trouble maintaining battery SOC levels. Take my wife's Kia Sportage for example. It'll sit parked in the garage for days on end and never has an issue with battery SOC levels. Start it up and let it idle and even with the hvac off it's pumping 13.8-14.5v into the battery all the time and easily keeps the battery at 100% SOC. Compare that to ours where we're lucky to get 12.8v unless we trick it to increase voltage draw and for many still struggles to keep it at 80% regardless of what the SOC is set to.

Unless Ford releases some smaller reliable ultra high MPG cars to offset the low numbers because about all they make now are trucks we're stuck dealing with this crap. Well that is unless someone can come up with a way to reprogram the ridiculous base charging strategy Ford's genius engineers set and actually pump current into the batteries...

The inconsistencies, make it hard to figure. I had (have?) a fix, that lasted near a yr. twice. Samson is just now getting his first warnings, on a 22. Some change the engine batt and poof, like magic.

Some have trucks that sit for days, or even weeks, others drive daily and still have troubles.

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[Porpoise Hork]

Yeah.. I suspect that the many of the underlying issues we have are at least in part caused by various modules not shutting down or are being woken up when the trucks are parked.

The only way to know if this is the case is to get a charger/maintainer that tracks and reports how much current it's outputted during the charge session. Hook it up and then check it daily to see what the truck(s) pulled from it the night before. From there investigate what modules are either remaining active or are kicking on overnight.

 

[ttnuagmada]

My assumption is that Fords battery aging/charging algorithm is just not well balanced for all types of driving, and that it's overly aggressive in some cases when determining battery age based on external parameters, and also maybe too aggressive when charging them when they're brand new, when it wouldn't have to if it didn't artificially limit the max SOC.

IE: The computer sees a slightly aged battery in terms of IR/capacity after I had the truck for a year, but then sees the ratio of starts/miles over the last several weeks because I live a mile from work and take a lot of short trips plus the battery temperature in Texas heat, and starts overcompensating with the charging strategy, which is worried about battery longevity.

Eventually things reach a point where I'm getting "system off to save battery" messages, so I reset the BMS. The truck goes back to charging based just on initial battery readings which makes the problems go away, but as it collects data over the course of a few weeks, it starts overcompensating and undercharging again, and then 5-6 weeks later I get messages again. Rinse repeat.

I did that for over a year after having the truck for about as long. Battery never failed an actual battery test, because the battery wasn't bad. It was just old enough to not measure like a brand new battery, and the truck was just too concerned about extending the battery life and was overcompensating based on external parameters that it factors into its aging algorithm.

I'm on battery 2, and I've not had this issue yet past the 2 year mark, but I can tell by looking at the SOC reading lately that I'm probably getting close to that point again. The only thing I did differently this time was raise the max SOC in Forscan when the battery was replaced. Not completely sure what difference this made, but my guess is that it gives the battery a wider operating range and the truck both A. doesn't charge it as agressively when it's new since it stays in the operating range for longer and B. gives extra headroom when it does start undercharging it, adding a few weeks/months before the SOC reaches borderline and starts throwing warnings again.

There's probably not really anything for Ford to "fix" because the strategy it uses probably actually is the best way to do things for the majority of drivers, but their algorithm is probably pretty basic and can't compensate properly for outliers.

 

[Davexxxx]

So, the weekend's fun with the BMS:
- Friday afternoon disconnect charger, KOEO: 77% @ 12.1V
- Friday evening arrived at destination, KO then KOEO: 83% @ 12.1V
- Sunday morning KOEO: 21% @ 10.9V, no crank.
I always carry a lithium jump starter so no problem when leaving Sunday afternoon. I do have to post this next photo because I've never seen this before. Approximately 1 hour into the drive home (KOER):

Some observations:
- It has never been to 100% before, ever. Notice that:
- the alternator is still pushing amps into the battery;
- still did so for the entire drive home although it ramped down to 1A
- the alternator is working its guts out, with 7A more than the typical 45A-ish being the norm on my truck

Some conclusions:
- the OBD Fusion Ford/Lincoln/Mercury PID for estimated SOC% must max out at 100 because my modified charging parameters have SOC% at 120; if it was only a true 100, there wouldn't be any current going into the battery
- It seems that the (effectively) complete discharge of the battery over the weekend has somehow woken up the BMS (or BCM?) to finally start taking notice of my modified charging parameters.

As usual, I will keep the truck on trickle charge at home and if anything odd happens, I'll let you know. I'm not bothering to put back the original BMS but it's stored away for a spare

How do you get that screen?

 

[Porpoise Hork]

From the icon of the engine on the right hand side it's likely to be the OBD Fusion app for iOS. it coasts $10 and works with most wifi and BT OBD2 adapters from the looks of it. Depending on which adapter you have will determine what level of access to the PIDs you get. I get most of the same info with the "Car scanner ELM OBD2" app and Vgate iCar Pro adapter but there are somethings others can see that I can't. Guess that's the difference between a $25 / $120 OBD dongle, and a 2.99 / 9.99 app.

 

[Davexxxx]

The only way to know if this is the case is to get a charger/maintainer that tracks and reports how much current it's outputted during the charge session.

I suspect we'll be seeing chargers with bluetooth apps before long.

 

[Davexxxx]

From the icon of the engine on the right hand side it's likely to be the OBD Fusion app for iOS. it coasts $10 and works with most wifi and BT OBD2 adapters from the looks of it. Depending on which adapter you have will determine what level of access to the PIDs you get. I get most of the same info with the "Car scanner ELM OBD2" app and Vgate iCar Pro adapter but there are somethings others can see that I can't. Guess that's the difference between a $25 / $120 OBD dongle, and a 2.99 / 9.99 app.

So there are devices short of Forscan, that can give more than error codes?

Do any of them allow changes, or only monitoring?

I'm not interested in full blown forscan. Its not that I'm unable, I just don't wanna.

But something else, I could be persuaded. Maybe.

 

[SilverPigeon]

How do you get that screen?

1. Bought A cheaper obdII adapter, a VeePeak BT+ BTLE from amazon
2. Bought OBD Fusion
3. Bought the Ford/Lincoln/Mercury enhanced library for my MY23. Make sure to get the library for your model year.

unlike the free OBDLink app, OBD fusion allows CarPlay display of PIDs.

 

[SilverPigeon]

So there are devices short of Forscan, that can give more than error codes?

Do any of them allow changes, or only monitoring?

I'm not interested in full blown forscan. Its not that I'm unable, I just don't wanna.

But something else, I could be persuaded. Maybe.

Without full FORScan, you won't make changes. You can use the FORScan lite apps and an obdII adapter to monitor on your phone/tablet. If the adapter is not on their list of supported ones, it may or may not work.

 

[Paul Neubauer]

Decided to replace my BMS module after reading this thread. The old module was always letting the battery get very low and routinely saw 65% SOC. The battery would never recover from the low voltage driving and the key fob had started not working anymore. Fully charged the battery and changed the module followed by a reset and the battery is finally charging and hitting the 80% target. This bad module may be the cause of a lot more of this trucks issues which I am waiting to see the outcome of.

 

[Paul Neubauer]

Old battery was still discharging faster than it would charge and quickly got back into the 60% range with low voltage DTC codes again. Replaced it over the weekend with another H8 Motorcraft and the new one recovers quick and doesn’t have the constant discharge problem. The charging system really doesn’t want the battery over 85% with that slow trickle charge of 4 amp and 13.3 volts.

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