BMS reset - no tools required

[angermgmt14]

2 questions,
I got a new OEM battery around October of last year and didn't know about the BCM reset. Should I still go to the dealer and get it done?
During the winter months I don't drive it that much so I take the battery out and put it on a battery tender in my basement. (Car is parked outside) Because I do this, am I going to have to reset the BCM when I put it back in? Or is it only when the battery is actually replaced with a different one? Thanks.

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[NeedForGreen]

2 questions,
I got a new OEM battery around October of last year and didn't know about the BCM reset. Should I still go to the dealer and get it done?
During the winter months I don't drive it that much so I take the battery out and put it on a battery tender in my basement. (Car is parked outside) Because I do this, am I going to have to reset the BCM when I put it back in? Or is it only when the battery is actually replaced with a different one? Thanks.

You only need to do it once when actually replacing it. If you lock the car and let it sit for 8 hours its supposed to reset it, but it still doesnt always work. Since you replaced it with another oem battery and not a different type like agm you should be good to go. If your voltage looks good and you dont see odd behavior with it you should be ok.

 

[Farkel]

I started this thread, so I feel like I should post an update. My DieHard AGM was acting 'funny' (on my Griot's charger/maintainer and on the car's voltage display), so I got a new Odyssey AGM. When the DieHard came out there was a pool of liquid in the bottom of the battery box, so there really was a problem with that battery. Before I changed it, I downloaded Forscan Lite to my phone and bought the OBDII adapter recommended on the Forscan site. I would highly recommend purchasing these, even if you're only going to use it to reset the BMS. After doing the reset and leaving the car locked overnight, the battery, the charging system and I are all happy again.

Remember, the BMS reset tells the system the age of the battery, while the 8-hour 'sleep' tells it the state of charge. Two different things.

 

[Vlad Soare]

Remember the BMS reset tells the system the age of the battery, while the 8-hour 'sleep' tells it the state of charge. Two different things.

Exactly. That's the point that many seem to be missing.

 

[akmon]

I started this thread, so I feel like I should post an update. My DieHard AGM was acting 'funny' (on my Griot's charger/maintainer and on the car's voltage display), so I got a new Odyssey AGM. When the DieHard came out there was a pool of liquid in the bottom of the battery box, so there really was a problem with that battery. Before I changed it, I downloaded Forscan Lite to my phone and bought the OBDII adapter recommended on the Forscan site. I would highly recommend purchasing these, even if you're only going to use it to reset the BMS. After doing the reset and leaving the car locked overnight, the battery, the charging system and I are all happy again.

Remember, the BMS reset tells the system the age of the battery, while the 8-hour 'sleep' tells it the state of charge. Two different things.

Is there any difference between fordscan bms reset and the trick you explained at the first post? I did this one and It worked (battery icon flashed 3 times).

 

[Farkel]

Is there any difference between fordscan bms reset and the trick you explained at the first post? I did this one and It worked (battery icon flashed 3 times).

I am sorry, Alberto, but I do not have a way to be sure that the easy way really works. Yes, the battery icon flashes, but I do not have a way to display what the computer shows for the battery "days in service". "Days in service" is stored in the Body Control Module. Forscan or Forscan Lite will show the "days in service", and I do not know of any other way for you to see this number.

 

[Farkel]

Is there any difference between fordscan bms reset and the trick you explained at the first post? I did this one and It worked (battery icon flashed 3 times).

UPDATE: Thank you, Alberto, for making me think. Since my battery only had 4 days in service, I thought this would be a safe experiment. I used the quick method, saw the battery icon flash, then checked the "days in service" using Forscan. IT WORKS! "Days in service" went from 4 to 0.

 

[akmon]

UPDATE: Thank you, Alberto, for making me think. Since my battery only had 4 days in service, I thought this would be a safe experiment. I used the quick method, saw the battery icon flash, then checked the "days in service" using Forscan. IT WORKS! "Days in service" went from 4 to 0.

Very very useful information. It´s the first time somebody contrast the bms reset trick with the information of Forscan. And the best of all, it works! Good idea to update the first post.
Now I know the procedure is well done and it´s enough.
Thank you for your time to test this experiment.

 

[Farkel]

Very very useful information. It´s the first time somebody contrast the bms reset trick with the information of Forscan. And the best of all, it works! Good idea to update the first post.
Now I know the procedure is well done and it´s enough.
Thank you for your time to test this experiment.

You are quite welcome! De nada.

 

[Tperk]

I am sorry, Alberto, but I do not have a way to be sure that the easy way really works. Yes, the battery icon flashes, but I do not have a way to display what the computer shows for the battery "days in service". "Days in service" is stored in the Body Control Module. Forscan or Forscan Lite will show the "days in service", and I do not know of any other way for you to see this number.

I am new to this forum but I did do the BMS reset after I put a new battery in my car and it seemed to work but my PATS system still does not work. The light on the dash does not blink anymore. Do you have any idea how to reset this? Any advice would be appreciated! Thanks! My car is a 2016 Mustang GT! I hope I posted this to right place.

 

[Farkel]

I am new to this forum but I did do the BMS reset after I put a new battery in my car and it seemed to work but my PATS system still does not work. The light on the dash does not blink anymore. Do you have any idea how to reset this? Any advice would be appreciated! Thanks! My car is a 2016 Mustang GT! I hope I posted this to right place.
Some settings get cleared from memory when the battery is disconnected. I don't know if the alarm does this, but if it has a choice of settings you might want to check whether its set the way you want. (Also posted in response to your same question in the General forum.)

 

[Postal Bob]

My story. Tried this last Nov on my F150 after I got a new battery. Worked like it's suppose too with the flashing battery symbol afterwards.
Took my Gt350 after a 3 month winter storage outside. It was kept on a battery tender the whole time. I noticed while driving, whether on highway or locally, that the voltage read 15v. It didn't change with the car speed or accessories being turned on. So I tried the reset procedure. No flashing battery symbol. Tried it again, same thing. Took the car for a drive, and immediately saw the voltage fluctuating with driving speed, like it always did.
I don't know if the reset worked, but it doesn't give the flashing battery symbol. But my voltage readout is reading how it always has.

 

[Buldawg76]

My 2020 ecoboost stang battery voltage readout shows either 15.0, 14.5 or 14.0 depending on how long the car sits between drive times. If it sits for 3 or more days it shows 15.0 volts charging for about the first 5 to 10 miles depending on outside temps and vehicle speed being driven. Then it drops to 14.5 volts and if driven for a long distance/time will eventually drop to 14.0 volts.

This is a normal condition where the alternator/computer in the car is optimizing the charge volts/amperage to bring the battery back to full charge without overcharging or causing damage to the battery.

BD

 

[Postal Bob]

My 2020 ecoboost stang battery voltage readout shows either 15.0, 14.5 or 14.0 depending on how long the car sits between drive times. If it sits for 3 or more days it shows 15.0 volts charging for about the first 5 to 10 miles depending on outside temps and vehicle speed being driven. Then it drops to 14.5 volts and if driven for a long distance/time will eventually drop to 14.0 volts.

This is a normal condition where the alternator/computer in the car is optimizing the charge volts/amperage to bring the battery back to full charge without overcharging or causing damage to the battery.

BD

But like I stated, it was on a battery tender continuous for 3 months, which should've had it at full charge.

Also, don't know why the reset didn't show any indication of happening. Yet in my F150, it worked as stated.

 

[Buldawg76]

Yes, the battery tender maintains it, but it is in a float mode of around 13.2 volts at 4 to 500 milliamps charge rate. The computer does not see that as being a fully charged battery when first starting after storage, so it charges at full capacity until it sees the battery responding to the charge rate and begins to taper the voltage gradually.

I do not understand the programming logic the engineers write into the computers charge regime but their much smarter than myself also.

BD

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