AGM battery

[pbnj]

I’ve seen it posted that some recommend moving to an AGM battery. Is this an attempt to mitigate the auto shut down? If you replace, do have to conduct a battery reset of sorts to let the vehicle know it has a new battery?

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[Timon.Arg]

From what I’ve been able to gather, switching to an AGM battery can definitely help, but more as a mitigation than a direct fix.

The “auto shut down” or battery saver behavior (I think you are talking about that) is usually triggered by low voltage or the system estimating that the battery is weak. AGM batteries tend to hold voltage better under load and handle cycling more efficiently, so they reduce the chances of those conditions happening.

Regarding the replacement: yes, it’s recommended to perform a BMS (Battery Monitoring System) reset. The vehicle keeps track of battery condition over time, and if you don’t reset it, it will still “think” the old battery is installed and may not manage charging correctly. (At least in most new vehicles is likie that)

With FORScan, there’s a specific function for this (Battery Monitoring Reset), which is the proper way to do it.

Additionally, it’s worth checking how the vehicle is configured from the factory in terms of battery management. Through FORScan, you can access the configuration parameters in modules like the BCM/BMS, where the system defines whether Battery Management System (BMS) is active and how it handles charging strategy. These parameters indicate if the vehicle is set up to properly manage different battery types. Even if you install an AGM battery, the system will still work, but if the configuration is not aligned, it may not be fully optimized in terms of charging behavior and battery life.

That said, everything I’m sharing here is based on information I’ve been gathering from different posts and forums as I learn more about the system. I’m not an expert on the subject, so I’m also trying to better understand how it all works in practice.

 

[Dude]

And a Ford employee on this forum stated to get the replacement battery fully charged (e.g. by sufficient driving, a battery maintainer, etc) then perform the BMS Reset

I don’t know if it’s necessary but I did that a few weeks back after getting a new AGM Battery (followed up by throwing salt over shoulder)

 

[pbnj]

I saw a video where putting the vehicle in ac mode, then flashing your brights 5 times, followed by 3 pumps of the breaks, will initiate a reset. The video shows this happening on the speedo display.

 

[Dude]

Regarding using FORScan (or Ford tools) to check and (correct if necessary) the battery type and other battery/charging system configuration matches the installed battery, that has been debated in the following post.

Jury is still out on that but if you have specific dealership service procedures for setting the battery type (AGM, EFB) please share

https://www.broncosportforum.com/forum/threads/what-gives-bad-battery-leads-to-new-discovery.20137/post-312612

 

[Timon.Arg]

FIY

https://www.broncosportforum.com/forum/threads/battery-replacement-procedure.10255/post-177887

 

[Dude]

FIY

https://www.broncosportforum.com/forum/threads/battery-replacement-procedure.10255/post-177887

That’s a post from me which I edited just now to include the recommendation to get the replacement battery fully charged before performing the BMS Reset and that post includes a YouTube video from a Ford Tech with some info on how Ford’s BMS works

 

[Unicorn]

It should be an AGM, it should always have been an AGM but there was a shortage early on so Ford was using an EFB. The AGM is better for handing deeper drains and charges faster.

There is a simple method for resetting the BMS, and I think it's in the manual. At least the latest one.

If you don't do it though, it will reset itself after 6 to 8 hours of it sitting there off. The same thing will happen if you charge it by connecting the charger directly to the battery posts instead of having the negative terminal on ground on the other side of the BMS. So connect to the body and not directly to the battery to save the time.

 

[coopny]

Should the BS have always shipped with an AGM?
I agree with @Unicorn - the Bronco Sport always should have shipped with an AGM, but as it was introduced in the era of COVID shortages, they flipped back to an EFB.

Let's take a look backthrough the owner's manual specifications:
2021 BS - only BHEF-48H6 (the EFB)
2022 BS - the EFB as the main part with BAGM-48H6-760 (the AGM part) as "alternative battery". It says the BMS must be configured to use the battery correctly in the fine print (no mention of how to do so, it says "Consult your local dealer or service provider for further details).
2023 BS, 2024 BS - BHEF-48H6A (still an EFB, but iterated part number) or alternatively BAGM-48H6-760.
2025 BS, 2026 BS - Ford doesn't even put a part number, just a generic ask your dealer message

So Ford went from recommending an EFB, to saying EFB alternatively AGM to just not saying a battery part at all, your dealer will tell you.

So what changed - why isn't Ford recommending EFBs anymore?
NHTSA investigation RQ24014 opened for the Bronco Sport in late 2024 for "loss of motive power". Let's scope part of its summary.

On April 12, 2024, Ford issued safety recall 24V-267 covering 456,565 MY 2021-2024 Ford Bronco Sport and MY 2022-2023 Ford Maverick vehicles. The recall addressed loss of motive power resulting from sudden degradation of the 12V battery during the drive cycle. The recall remedy consisted of software updates to the body control module and the powertrain control module. The updated software aimed to provide warning to consumers when the battery is failing and inhibit certain vehicle functions which can lead to loss of motive power incidents. Additionally, Ford removed the existing 12V Enhanced Flooded Battery (EFB) as both a service component for the subject vehicles and original equipment for newly built Bronco Sport vehicles (during MY 2024 production), replacing it with a more robust absorbed glass mat (AGM) battery. The same AGM battery had been incorporated into Ford Maverick production in late 2022.

So during builds in the 2024 model year, Ford stopped using EFBs entirely, and no longer considers an EFB a "service component" for existing vehicles... which should mean Ford is not using EFBs at all at this point (warranty or paid battery replacements and new BS construction).

Is this an attempt to mitigate the auto shut down?
No. An AGM battery charges more quickly and delivers power down to deeper discharges more reliably. Your vehicle will still automatically start/stop if that functionality is not disabled in some way (manual switch, autostop elimination device, programming using FORscan and a compatible OBDII reader, putting load on the inverter in the cargo area [the manual explicitly advises against continuous load on the inverter for safety reasons]) and your battery has adequate charge according to the BMS.

Should I replace my EFB?
If you are in warranty and not in relatively isolated locations, I would have your battery regularly tested. You can get your own tester on Aliexpress for <$20, or you can just occasionally have somewhere that services your car or an auto parts store test it for free. If it fails within 3yr/36K on the tester, congrats, Ford owes you a battery.

If you're going to relatively isolated locations (no cellular service) and/or you are out of the bumper-to-bumper warranty, this becomes a tricker situation. Theoretically if the battery reaches a state where it should be replaced, the BMS should detect this, the vehicle should throw a gauge cluster message, and it should trigger an alert in FordPass. This happened to my parents who have a 2023 Expedition (same size battery, but it shipped with the AGM part) and a little over in two years of ownership the battery failed a test [recharge, then retest, then failed]).

However, this software is not perfect - there have been multiple software recalls for these systems and the NHTSA investigation was because two prior recalls hadn't fully addressed the problem and people got left with vehicles that wouldn't restart from an auto-stop event while on the road.

For me, where the dealer tested the battery and it gave a pass, but it was going to <12V within seconds of turning off the ignition - I just decided to replace the battery with an AGM for piece of mind.

If you're going offroad to locations that don't have cellular service and the EFB battery isn't exceeding its rated CCAs I would just replace it to be honest. Trying to wait until Ford warranties it isn't worth the chance of being stranded without being able to summon a tow.

Do I need to reset the BMS after battery replacement and how to I do it?
Already covered upthread, but all you have to do is turn the vehicle to on (no engine start), flah the high beams five times by pulling back on the signal lever, and then tap the brake pedal three times. The battery light in the upper left corner of the gauge cluster will blink a few times. You're odne.

Do I need to change the programming of vehicle's PCM module to reflect the new battery type?
I already had FORScan and my vehicle was already set to AGM charging on its programming. I'm not sure if the BCM flipped this switch automatically, or if it was already set like that. May be worth asking your dealer to check.

 

[Happy Joe]

During off roading the only difference that I have seen is that flooded batteries can spill.
and I doubt that These BS's can get in those positions without rolling; or otherwise getting all four tires off the ground.

Enjoy!

 

[rugedraw]

I saw a video where putting the vehicle in ac mode, then flashing your brights 5 times, followed by 3 pumps of the breaks, will initiate a reset. The video shows this happening on the speedo display.

That method works just fine. What you want to do (even if you bought the battery brand new) is charge it to 100% before you reset the BMS. Do not assume that just because the battery is new, that the state of charge is at 100%. If the battery is at say 97% when you install in and reset the BMS, then the system will think it is at 100% when it is at 97%, and the BMS data quality is compromised. Not a humungous deal if the difference is something nominal like that, but if you're going to do it, might as well do it right.

What @Timon.Arg mentioned about checking if the vehicle is configured to have an AGM battery not has been discused in a few forums and some people feel it is not necessary and report having no issues without chaning the configurration to reflect it now has an AGM battery in it. IMO, if that setting is there, it is for a reason. Personally, I would change it.

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