BMS reset - no tools required

[GT4EVR]

Marc (@Farkel), I want to thank you for the info contained in the initial posting under this topic. Yesterday I replaced the 2.5 year old OEM 390 CCA battery in my Shelby with a new 96R series 590 CCA battery purchased from my local Ford dealer. Lacking any Forscam capability, I performed the reset procedure you described to establish the beginning "days in service" of the new battery in the Body Control Module (BCM), and received 3 confirmation flashes of the battery icon. (This is something that Ford should have provided in the vehicle manual.) I then left the car locked and undisturbed for at least 8 hours, as indicated in the manual, and subsequently drove the car at least 10 miles to ensure the Battery Management System (BMS) would "learn" the charge condition of the new battery. Since there were no warning icons of a problem, it appears everything worked out well.

Good that you also re-posted the previous comments of @JAJ and @Vlad Soare who offered some further insight on this subject, so thanks to you guys as well.

As a bonus, when changing the battery, I didn't lose any stored memory settings thanks to the "SUPPLY" mode function of my CTEK 7002 Battery Tender/Maintainer, which supplies a steady 12V current when connected to my car's positive and negative battery cables before disconnecting them from my battery.

It's great to have information shared on this forum that benefits others!

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[Farkel]

...It's great to have information shared on this forum that benefits others!

You're welcome, Robert. On top of all the good-natured, opinionated and entertaining posts, this forum is like an encyclopedia of Mustang knowledge and experience. I'd be lost without it.

 

[Postal Bob]

Replaced by battery today. Kept the battery tender hooked up to the battery cables when disconnecting battery. It worked in that I didn't lose any memory settings. And then I tried the BMS reset procedure, but nothing happened. No flashing battery signal. I tried several times, but still nothing. It does work on my F150 though. Can't figure out why one works, and one doesn't? I'm following the procedure just as described. Only difference between my truck and the car is the truck has a key ignition, and the Shelby is a push button.

 

[Farkel]

Replaced by battery today. Kept the battery tender hooked up to the battery cables when disconnecting battery. It worked in that I didn't lose any memory settings. And then I tried the BMS reset procedure, but nothing happened. No flashing battery signal. I tried several times, but still nothing. It does work on my F150 though. Can't figure out why one works, and one doesn't? I'm following the procedure just as described. Only difference between my truck and the car is the truck has a key ignition, and the Shelby is a push button.

I wish I could help, but my knowledge is limited to what's in this thread. The reset does seem to be important, thanks to these cars being 'smart'er than us humans. Forscan, even Forscan Lite, will get the job done if you want to avoid a dealership visit.

 

[Postal Bob]

Ok, got it to work. My own impatience was the problem. I needed to heed this in the procedure:

1. If successful the battery light will flash 3 times within the next 15 seconds

Apparently in my car, it took almost 15 seconds for the battery light to flash. I was giving up too soon, and turning off the ignition early.
Thanks for the info on this.

 

[19gtaz]

Good information, thanks everyone, expecially @Farkel

 

[Skye]

After replacing my battery (with an AGM), I've been trying to avoid paying the dealer for a BMS reset, and I don't have Forscan or even a computer. I found the following on an F150 forum. Tried it on my '20 GT and it seems to work.

Procedure must be carried out within 10 seconds:

1. Switch ignition on (engine off)
2. Pull and release high beam 5 times.
3. Press and release brake pedal 3 times.
4. If successful the battery light will flash 3 times within the next 15 seconds
5. BMS reset completed.

I'm not any kind of expert, but my battery icon flashed three times after performing these steps, so the procedure appears to work. YMMV

UPDATE: 3/3/2022
Confirmed with Forscan. This procedure resets the "days in service" to 0.

Used this today first time to reset BMS and it worked great. Thanks for posting.

 

[galaxy]

TL;DR

Sorry if it was burried in the thread, but where's the "why"? Why does this reset procedure need to be done? What does it accomplish? What bad thing would happen if you didn't do it after instaling a new battery? Just learning!

 

[K4fxd]

Why does this reset procedure need to be done?

It tells the car that it has a new battery and then uses a charging stratagy for a new one. If you don't reset, the car will think the battery is several years old and will not properly charge it.

 

[Vert]

I changed my battery almost a year ago and never did a thing and no issues this far. Car only gets driven 2-3 times a week so it sits for long periods.

 

[K4fxd]

I don't know if it is necessary. My battery went out when I was in Fl last. I didn't have my forscan cable. When I got home and hooked up, the car had learned that I put gel cell battery in it and it knew the cca and amp hours.

 

[DougS550]

TL;DR

Sorry if it was burried in the thread, but where's the "why"? Why does this reset procedure need to be done? What does it accomplish? What bad thing would happen if you didn't do it after instaling a new battery? Just learning!

Because the Ford Manuals says too, doesn't matter why even though I know it is to reset the system TO relearn.

 

[Vlad Soare]

TL;DR

Sorry if it was burried in the thread, but where's the "why"? Why does this reset procedure need to be done? What does it accomplish? What bad thing would happen if you didn't do it after instaling a new battery? Just learning!

The car uses an adaptive, intelligent charging strategy, which depends on several criteria, one of which is the age of the battery. This strategy not only increases the overall efficiency, but most importantly, it prolongs the life of the battery. If you install a new battery, but the system charges it as if it were old, you won't get the best out of it and may even have other issues, like the load shedding feature activating when it shouldn't.

 

[DougS550]

It tells the car that it has a new battery and then uses a charging stratagy for a n

ew one. If you don't reset, the car will think the battery is several years old and will not properly charge it.

 

[Vert]

To me, I look at it like this. Battery dies and once that happens, the system gets drained of all power and stored energy. Thus the BCM should reset. I'll see what happens the next couple of years if I still have it by then and a battery is under 200 bucks.

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