BMS reset - no tools required

[Johnnybee]

See post #20

Presumably the scan tool is used because it would be available in a Ford shop. The below, from the (2018) owner’s manual.

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[DougS550]

Presumably the scan tool is used because it would be available in a Ford shop. The below, from the (2018) owner’s manual.

I can honestly say I was keeping my car unlocked during the winter during charging, not charging, removing etc, I must have overlooked reading this procedure in the manual. As far as the Idol and drive after battery replacement/Disconnect/Reconnect ETC? Same, Same.
Live and Learn. Thank for posting and sharing.

 

[ice445]

This didn't work on my 2020 for some reason. But luckily, ForScan Lite does have the BMS reset function under the Service section. This is something that wasn't immediately apparent from casual googling, so hopefully this helps someone, eventually. As far as if it's actually necessary versus the 8 hour magic wait time, I would think that it's necessary to do both based on what I've read. The car can't determine battery age from learning its state of charge (although it can probably determine the battery type since AGM cells have slightly higher overall voltage).

 

[NeedForGreen]

I happened to try this when I swapped my battery out. I got the flashing battery light, but can confirm this did not reset the bms nor did letting it sit for 8 hours. Forscan is easy and thankfully I have it. If you switch different batteries like to an agm I would do a proper reset or let the dealer do it. If you notice your battery voltage varying and not staying study that's a sign the bms needs a reset.

 

[The Demon]

I happened to try this when I swapped my battery out. I got the flashing battery light, but can confirm this did not reset the bms nor did letting it sit for 8 hours. Forscan is easy and thankfully I have it. If you switch different batteries like to an agm I would do a proper reset or let the dealer do it. If you notice your battery voltage varying and not staying study that's a sign the bms needs a reset.

Bummer. I had this printed out as I am expecting a battery change soon. I'll still try it but keep an eye out to see if it worked.

 

[Firsttexan]

I replaced mine 2 yr old battery with a standard replacement. No batt warnings.

Is this an issue when converting to an AGM battery?

 

[NeedForGreen]

I replaced mine 2 yr old battery with a standard replacement. No batt warnings.

Is this an issue when converting to an AGM battery?

If you swap to the exact same type of battery not really, but voltages are slightly different for agms so a bms will have to be done.
You won't get warnings just the bms will be confused and not work as it's supossed to.
I had a tech at a new dealer I saw today say anytime you replace a battery a bms reset needs to be done. I mentioned the steps posted here and he said no idea what it really does, but said extremely doubtful it actually resets the bms.

 

[Brokestang]

Anything to make you come back & pay the stealership for something that's stupid & unnecessary.

 

[Firsttexan]

If you swap to the exact same type of battery not really, but voltages are slightly different for agms so a bms will have to be done.
You won't get warnings just the bms will be confused and not work as it's supossed to.
I had a tech at a new dealer I saw today say anytime you replace a battery a bms reset needs to be done. I mentioned the steps posted here and he said no idea what it really does, but said extremely doubtful it actually resets the bms.

I have Forscan. I will give it a look.

 

[NeedForGreen]

I have Forscan. I will give it a look.

Super easy that way. It's even listed as battery management system.

 

[NeedForGreen]

Anything to make you come back & pay the stealership for something that's stupid & unnecessary.

If the dealership tries to charge you then try another one. My dealer doesn't charge anyone to do it.
Forscan membership and an odb reader would still cost more unless you have user for Forscan.
I wouldnt say it's unnecessary either. You want your battery to recharge properly. If your bms thinks your battery is at 13.5V but it's something different its going to mess with your batteries life in the long run and other things in your car. If it thinks your battery is at 11V it will still shut things off to save power even though you have a new battery.
The letting your car sit for 8 hours didn't work for me, but may work for others.

The bms actually does quite a bit.

 

[ice445]

I happened to try this when I swapped my battery out. I got the flashing battery light, but can confirm this did not reset the bms nor did letting it sit for 8 hours. Forscan is easy and thankfully I have it. If you switch different batteries like to an agm I would do a proper reset or let the dealer do it. If you notice your battery voltage varying and not staying study that's a sign the bms needs a reset.

Makes sense. It seems like the BMS has different charging voltages it can select based on the state of battery charge and the demand on the system, but when it picks a voltage it stays steady, at least on my car post reset. If it's sat for a week it sits at 15.2 for a while, or 14.8 at idle, then slowly tapers down to 13.8 and tends to sit there once the battery finishes charging up.

 

[Brokestang]

If the dealership tries to charge you then try another one. My dealer doesn't charge anyone to do it.
Forscan membership and an odb reader would still cost more unless you have user for Forscan.
I wouldnt say it's unnecessary either. You want your battery to recharge properly. If your bms thinks your battery is at 13.5V but it's something different its going to mess with your batteries life in the long run and other things in your car. If it thinks your battery is at 11V it will still shut things off to save power even though you have a new battery.
The letting your car sit for 8 hours doesn't work. Did zilch to mine.

The bms actually does quite a bit.

I didn't mean it's unnecessary in the sense of the car itself. I meant that they design stuff into these new cars today that's not necessary. Never owned a vehicle that had things like this.

 

[Firsttexan]

I didn't mean it's unnecessary in the sense of the car itself. I meant that they design stuff into these new cars today that's not necessary. Never owned a vehicle that had things like this.

It's an advanced computer on wheels. It's where things are headed. Electric cars will take a lot of the moving parts away. But not the complication. Hybrids and ICE will get increasingly complex but you get higher performance in exchange.

 

[Buldawg76]

I have not actually looked at the battery on my 2020 mustang to see if it is an AGM or flooded battery, but I do know my 2019 Edge I just traded for the stang had an AGM battery in it from the factory and had gone bad under warranty, so the dealer replaced with an motorcraft AGM battery.

BD

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