2.3 Liter Battery Replacement

[Bill K]

After you swap the battery you should reset the BMS—battery management system.

I usually use FDRS to do it. But there is a manual way to do it as well... if I recall you have to flash the high beams 5 times followed by press the brake pedal 5 times (or something like that). But I'm sure Google can assist with that.

EDIT— Looked it up.

1. Power on vehicle (engine not running)
2. Flash high beams 5 times
3. Press brakes 3 times
4. Wait for battery light to flash after 5-10 seconds
5. Power cycle vehicle

Thanks for this. Any idea what the BMS system is doing behind the scenes for the required dance steps above? I've disconnected my current OEM battery a number of times when I've left for extended periods and haven't done anything special except reconnecting when I get home - kind of seems like a new battery install but what do I know?

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[Bill K]

Thanks for this. Any idea what the BMS system is doing behind the scenes for the required dance steps above? I've disconnected my current OEM battery a number of times when I've left for extended periods and haven't done anything special except reconnecting when I get home - kind of seems like a new battery install but what do I know?

Nevermind - a previous post summed it up... I'll save the dance steps above for my future replacement...

 

[Signals34]

Thanks! I didn't know this was a thing, I'll reset mine today. My OEM battery died last year, replaced it with an X2. I'm like WTF, so I asked ChatGPT (who reads the manual?) why the reset is needed:

The Battery Monitoring System (BMS) reset is needed on a 2021 Ford Bronco (and many modern vehicles) after changing the battery because the BMS is responsible for monitoring the battery's health, charge, and performance. When the battery is replaced, the system needs to be recalibrated to the new battery to ensure optimal operation. Here's why it's necessary:

1. Accurate State of Charge (SoC) Monitoring:
   The BMS tracks the battery's state of charge. When you install a new battery, its charge characteristics differ from the old one. Resetting the BMS allows it to correctly measure and adapt to the new battery's charge capacity and condition.
2. Preventing Overcharging or Undercharging:
   If the BMS isn't reset, it might use incorrect data from the old battery, which can lead to overcharging or undercharging. This can reduce the lifespan of the new battery or cause charging system issues.
3. Battery Age and Performance Tracking:
   The BMS uses data to assess the battery's age and condition. Without a reset, it may assume the new battery is still the old one, leading to incorrect performance monitoring and diagnostics.
4. Avoiding Dashboard Errors:
   Failing to reset the BMS can trigger warning lights or error messages on the dashboard, as the system may detect inconsistencies between its stored data and the actual battery performance.
5. Improved Start-Stop System Functionality:
   If your Bronco has a start-stop system, it relies heavily on the BMS to determine when to stop and restart the engine. An improperly reset BMS can disrupt this feature, leading to inefficiency or malfunctions.

If you replace the battery on a 2021 Ford Bronco and do not reset the Battery Monitoring System (BMS), several warnings or issues may appear on the dashboard, including:

1. Battery Warning Light:
   The battery icon may illuminate, indicating the system detects an issue with the battery or charging system.
2. "Service Battery System" Message:
   A message may appear on the instrument cluster advising you to service the battery system.
3. Check Engine Light (CEL):
   The BMS may trigger a diagnostic trouble code (DTC), which could cause the Check Engine Light to illuminate.
4. Stop/Start System Disabled:
   If your Bronco is equipped with an automatic start-stop system, it may stop functioning, and you could see a message like "Start/Stop Not Available."
5. Inconsistent Voltage Readings:
   The vehicle may incorrectly assess the battery's charge, resulting in fluctuating voltage levels shown on the dashboard.
6. Dimming Lights:
   The BMS might not regulate the charging system correctly, leading to issues like dimming headlights or cabin lights.
7. Reduced Battery Performance:
   The battery may not charge properly, and you might experience trouble starting the vehicle or reduced overall electrical performance.

i changed the battery in my rubicon, 2019, last year, i did none of this reset garbage, never had any lights or issues...seems like just another way to bring it to the dealer to pay them more money....unless jeeps don't count as a modern vehicle...lol...

 

[ejaffe]

I was thinking I may go to this when the battery needs replacing.

https://www.genesisoffroad.com/products/gen3-bronco-dual-battery-kit

 

[Mr Bacon Jr]

I was thinking I may go to this when the battery needs replacing.

https://www.genesisoffroad.com/products/gen3-bronco-dual-battery-kit

Just had my battery replaced under warrnaty yesterday. 19 months, 23,000 miles. I was getting random error messages, tried to chrge battery myself overnight with no luck.

I was thinking about doing the Genesis dual battery setup, but I have all my lights and cell booster running though the aux swithes, which are tied to iginiton on/off. So moving them oer to the “aux” battery woudl not really get me anything.

 

[Alanp970]

Had my 2022 Bronco Badlands Sas 2.3 L in for routine service. They told me I needed a new battery because my actual cold cranking amps were down to 565 from factory 800. My rig is two years, five months old w/ 52k miles. Haven’t been having any problems. Told them I’d replace it next oil change. Tried searching the topic here and I’m not finding much. Physically changing a battery isn’t difficult. Is there anything more such as telling the computer it’s a new battery, etc? Any help would be;d be appreciated.

Thanks. Contented

The testers will fail a battery when they get down to about 70% of rated CCA. Keep in mind the auto start stop battery is something closer to 200 CCA so at 565 you still have way more than you need and I’m sure that’s why you’re not noticing it having any difficulty starting. If they’ll replace it under warranty then go for it. Otherwise you’re throwing away a battery that probably has quite a bit of life left in it.

 

[Boreal]

Depends on how much the vehicle is driven, how far it's driven in a trip. Short trips don't have the time to charge the battery, especially deep cycle like these agm's.

100% agree
My commute is 37 minutes at highway speeds, with weekend excursions being around 2.5 hours per day. Of course, there are always a few little trips to and from… but even in the deep of winter, -30 temps, I’m driving long enough to get up to full operating temp.

I don’t know how you can get any more ideal than this for replenishing a battery day to day and maintaining health. There’s never been a State Saved notice, ASS has always worked, voltage is always strong and charging is usually on “Float”.

So, from my POV either the battery isn’t robust enough for the use, or they are a faulty design to continually fail the CCA tests

 

[Brian_B]

I’m guessing since you see charge voltage the alternator has tested ok.

And the BMS is being reset each time a new battery is thrown in there.

Maybe time to try replacing the BMS module itself - it may be reading faulty or something?

 

[dgorsett]

After you swap the battery you should reset the BMS—battery management system.

I usually use FDRS to do it. But there is a manual way to do it as well... if I recall you have to flash the high beams 5 times followed by press the brake pedal 5 times (or something like that). But I'm sure Google can assist with that.

EDIT— Looked it up.

1. Power on vehicle (engine not running)
2. Flash high beams 5 times
3. Press brakes 3 times
4. Wait for battery light to flash after 5-10 seconds
5. Power cycle vehicle

Replaced my battery today. Did these steps several times before and after a drive and never got the flashing battery light?... OM pg 337 did say to leave it parked doors locked for eight hours, we'll see.

 

[dgorsett]

Replaced my battery today. Did these steps several times before and after a drive and never got the flashing battery light?... OM pg 337 did say to leave it parked doors locked for eight hours, we'll see.

Still getting low battery warnings, reset still doesn't acknowledge.....

 

[PWillette]

Still getting low battery warnings, reset still doesn't acknowledge.....

Maybe try pulling the negative to reset and try again?

 

[Brian_B]

A lot of these cheat codes are ridiculously hard to put in if you don’t get the timing just right. And some of them just flat out don’t work on certain trims for some unknown reason.

If you haven’t already watched a video of someone doing it - that can help if it’s just a timing thing.

 

[KillerPenz]

A lot of these cheat codes are ridiculously hard to put in if you don’t get the timing just right. And some of them just flat out don’t work on certain trims for some unknown reason.

If you haven’t already watched a video of someone doing it - that can help if it’s just a timing thing.

You aren't kidding there... Wait til you have to enter the cheat codes in to put your brakes in "service" mode. What a pain in the ass that was.

Back on topic though, and sure it doesn't make anyone feel any better about it, but I'm 3 years in, just over 79k miles and still rocking the original battery. Like anything on the Bronco it seems to be a crap shoot as to what someone will have go wrong (bad) next.

 

[dgorsett]

Maybe try pulling the negative to reset and try again?

Well, thiss along with maybe inputting faster seemed to do it, got the acknowledgement. Now we'll see if the battery weirdness quits..

 

[dgorsett]

After getting the BMS reset to take yesterday and a 200 mile drive today I got ASS, Horsey video and it' dropped from 15.2 to 13.8 V on the trip.

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