4th battery in less than 5 years

[UNCGrad]

I was just told that my battery failed its test. I had the original replaced under warranty. The next time it started going g bad Ford said no to replacing it again so I replaced it through Advance Auto. Now I'm told that I need to replace it again. Is there an issue with 2021 3.5 EB? The truck does sit Monday through Friday with an occasional errand during the week but it gets driven on the weekends and I just got back from driving 1200 miles last weekend. I'm almost at 75k.

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[digitaltrucker]

Is it a 6, 7 or 8? I replaced the dealer installed H6 in my used 21 with a Walmart H7. Weird that the as built data was set for an H7 and the dealer put in the H6, must have been all they had.

I dont think you are driving it enough, put a tender on it and or check for a parasitic draw.

 

[JTL89]

I vaguely recall a phantom battery issue with some of the 21 models. If I'm not mistaken, a software update remedied the issue. Don't recall the date codes that was for though. Wouldn't think a healthy battery would be dying that quickly even if only driven once a week or so unless something was left on and drawing power.

 

[digitaltrucker]

Forgot to say that I also changed my charge max to 90% via ForScan.

 

[Porpoise Hork]

AGM batteries age extremely poorly when maintained at a lower state of charge. Every AGM manufacturer states that these types of batteries resting SOC voltage should be kept at at least 90-95% to maximize the lifespan of this type of battery chemistry. Ford in their infinite wisdom set the default SOC to 80% which effectively puts the battery into a permanant discharged state.

When kept in a partially discgarged state it can cause excessive sulfation development in the cell plates leading to shorting actoss them. Even if you drive it daily for enxtended periods of time the most it will charge the 12v system to is 80% and that's IF the conditions are present for the BMS to ramp up the charging voltage from 12.9 to 14.2v. This is usually when the headlights are on or if the HVAC blower is on speed 5 or higher. If the driver's door is opened or key fob not present inside the truck when it's running the charging voltage will dip to 12.9v. This issue is componded by those who do a lot of short drives or leaving it sit for days on end without being griven causing the SOC to dip down into the 70% range or lower.

Best options are to utilize Forscan and update the 12v battery SOC setting from 80% to at least 95% and for non Powerboost models, swap out the H6 or H7 battery for an H8 for the significantly increased reserve they have. you will need to get a larger battery blanket wrap for it but it will fit in there. If the truck is not driven daily then putting a bluetooth battery monitor on it wouldn't be a bad option so you can keep an eye on the voltage and be prepared to hook an AGM charger up to it when the battery resting voltage hits 12.5v or 80%.

 

[UNCGrad]

AGM batteries age extremely poorly when maintained at a lower state of charge. Every AGM manufacturer states that these types of batteries resting SOC voltage should be kept at at least 90-95% to maximize the lifespan of this type of battery chemistry. Ford in their infinite wisdom set the default SOC to 80% which effectively puts the battery into a permanant discharged state.

When kept in a partially discgarged state it can cause excessive sulfation development in the cell plates leading to shorting actoss them. Even if you drive it daily for enxtended periods of time the most it will charge the 12v system to is 80% and that's IF the conditions are present for the BMS to ramp up the charging voltage from 12.9 to 14.2v. This is usually when the headlights are on or if the HVAC blower is on speed 5 or higher. If the driver's door is opened or key fob not present inside the truck when it's running the charging voltage will dip to 12.9v. This issue is componded by those who do a lot of short drives or leaving it sit for days on end without being griven causing the SOC to dip down into the 70% range or lower.

Best options are to utilize Forscan and update the 12v battery SOC setting from 80% to at least 95% and for non Powerboost models, swap out the H6 or H7 battery for an H8 for the significantly increased reserve they have. you will need to get a larger battery blanket wrap for it but it will fit in there. If the truck is not driven daily then putting a bluetooth battery monitor on it wouldn't be a bad option so you can keep an eye on the voltage and be prepared to hook an AGM charger up to it when the battery resting voltage hits 12.5v or 80%.

Thanks for that detailed description. Is it too late for me to do the changes with Forscan with the current battery?

I picked up the truck and the dealership said they could not do the backup camera recall because of the battery. I took the truck to Advanced Auto. They tested it and said it was fine and would not replace it under warranty.

 

[Porpoise Hork]

With Advance Auto reporting the battery is healthy, Chances are the dealer is saying no to performing the recall because the battery SOC is too low and God's forbid their tech would have the the mental fortitude to realize they can just put a charger on it for a few hours then do the recall.

You can certainly give it a try since it won't hurt anything. If you don't already have one, get a charger designed for AGM batteries that will also do desulfation cycles like the Noco Genius 10. Make the update in Forscan then put it on charge and let it do its thing overnight. Once the main charge cycle is complete it will pulse the green light to notify it is in the desulfation cycle, which can take up to 8 hours to complete. Once completed the BMS will take between 6-8 hours of key off to properly update the battery SOC. Afterwards I'd keep an eye on the reported SOC for a few days to a week and if it remans stable then take it back in to get the recall done. If it starts dropping randomly consider replacing the BMS with the current revision part if yours has a date stamp earlier than 10/2023.

 

[bandyrdk]

I vaguely recall a phantom battery issue with some of the 21 models. If I'm not mistaken, a software update remedied the issue. Don't recall the date codes that was for though. Wouldn't think a healthy battery would be dying that quickly even if only driven once a week or so unless something was left on and drawing power.
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With Advance Auto reporting the battery is healthy, Chances are the dealer is saying no to performing the recall because the battery SOC is too low and God's forbid their tech would have the the mental fortitude to realize they can just put a charger on it for a few hours then do the recall.

You can certainly give it a try since it won't hurt anything. If you don't already have one, get a charger designed for AGM batteries that will also do desulfation cycles like the Noco Genius 10. Make the update in Forscan then put it on charge and let it do its thing overnight. Once the main charge cycle is complete it will pulse the green light to notify it is in the desulfation cycle, which can take up to 8 hours to complete. Once completed the BMS will take between 6-8 hours of key off to properly update the battery SOC. Afterwards I'd keep an eye on the reported SOC for a few days to a week and if it remans stable then take it back in to get the recall done. If it starts dropping randomly consider replacing the BMS with the current revision part if yours has a date stamp earlier than 10/2023.

I just had an update on my 2021 3.5 this week. The information about the update said it was to better optimize the charging system to maintain the battery.

 

[Porpoise Hork]

The OTA update attempted to resolve the hard coding issues with the BMS modules that were used on many Ford's 21-23's. Ford ultimately released a new revision ( ML3T-10C652-B ) sometime in October 23 that corrected the majority of issues. These issues could include incorrect SOC detection, failure to register charging events, random 10-20% 12v SOC drop overnight. All of which led to OTA update failures, modules being shut down and failing to boot correctly, and other odd electrical gremlins.

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