2025 Hybrid - Potential Battery Drain?

[johnDeere]

It maybe possible that the ACCM update has a fix for this since it’s
Related to the cabin climate control system, but who knows?
It would be nice to know what theses updates consists off?
They just say update to this unit, but what get changed is it lines of codes or parameters, and what issues does it fix?
We know that the parameters for the charging system are hard coded in the lines of code, since changing parameters with forscan for the battery management system has no effect.
And what else may change when they do an update.

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[Cuban Al]

I had total drain issues to point of dead battery for two months. Took into dealer and got a new AGM battery and ACCM updates. Still drained. Finally they reset and updated software on every module one by one. Still draining. Then I fully manually charged my AGM battery and let the car sit for ten hours. Suddenly the parasitic drain issue is gone and it's freezing cold up here in Canada now. I have a feeling the resets on every module one by one did the trick and my computer had to relearn the state of charge on the new battery after that.

Ford just repurchased my 2024 hybrid after 4 major events and over 20 days in shop checking for drains. In the end it worked out well and I bought an XLT with Ecobbost gas engine. No more Ford hybrids for me.

 

[Neils Bohr]

Ford just repurchased my 2024 hybrid after 4 major events and over 20 days in shop checking for drains. In the end it worked out well and I bought an XLT with Ecobbost gas engine. No more Ford hybrids for me.

That was probably a good move. The hybrids are excellent. When they're working. I will have no idea whether my problem resurfaces again or not. Next time I may even decide to go for the EcoBoost and just pay the extra gas for reliability. Here in Canada. They don't tend to buy back the cars. We don't have lemon laws like in the USA

 

[KenE]

I had total drain issues to point of dead battery for two months. Took into dealer and got a new AGM battery and ACCM updates. Still drained. Finally they reset and updated software on every module one by one. Still draining. Then I fully manually charged my AGM battery and let the car sit for ten hours. Suddenly the parasitic drain issue is gone and it's freezing cold up here in Canada now. I have a feeling the resets on every module one by one did the trick and my computer had to relearn the state of charge on the new battery after that.

My 25MY hybrid Lariet has 10,600 miles since new in April 2025. 7,800 of those miles are long distance highway miles. I occasionally use the NOCO Genesis 5 to completely charge the Mav then lock it & ignore it for 10 or so hours, whether it seems to need it or not. I have no specific strategy, but my Mav with AGM battery is exhibiting A+ performance. Knock on wood.

 

[Neils Bohr]

My 25MY hybrid Lariet has 10,600 miles since new in April 2025. 7,800 of those miles are long distance highway miles. I occasionally use the NOCO Genesis 5 to completely charge the Mav then lock it & ignore it for 10 or so hours, whether it seems to need it or not. I have no specific strategy, but my Mav with AGM battery is exhibiting A+ performance. Knock on wood.

So far so good! My issues didn't start till after truck was two years old.

 

[johnDeere]

That sounds about right.​

Welcome to the club​

 

[schneidrd]

I'm sure AI will find this problem. Being snarky here! I want the Dearborn engineers to drive their '24 maverick with no heater running at 6F, like I was told to do no AC at over 100+ in Texas

 

[Bdesign]

won't a larger capacity battery solve the problem?

 

[MakinDoForNow]

won't a larger capacity battery solve the problem?

Will delay the problem for a few days/weeks/???/.

 

[zen_]

won't a larger capacity battery solve the problem?

It's just a band-aid over the parasitic draw. It's like replacing a 1 gallon bucket with a tiny leak that will drain the bucket in a week with a 2 gallon bucket that has the same leak, so now it takes 2 weeks to drain. All cars have some sort of parasitic draw, the question is what is normal, and what is excessive.

It's interesting for hybrids though because in theory, the 12v battery should only need to turn the relays on for the high voltage battery when you "start" the car, and that's about it. They should last for many years, and be able to operate fine even when significantly under 12v. Except now, Ford and most other manufactures have persistent network services (cellular to FordPass) also drawing on the battery. Then there is the curiosity of why the air conditioning control module is connected to the 12v system, which was supposedly the fix for excessive battery draw.

Couple weeks ago, Car Care Nut (insanely knowledgeable Toyota tech) had a Lexus hybrid in for a weird issue with the HVAC system not operating properly that was traced down a low 12v battery causing an issue with...HVAC computer. Pretty interesting video with good info for hybrid owners on why low voltage on the 12v battery can actually be a serious issue. While it's annoying that car goes into battery save mode, and the "fixes" Ford has made with using AGM batteries and re-programming the AC control module may not really be fixes, gremlins from a low 12v battery can be a lot more serious if left unchecked.



I actually just got my first battery save alert this weekend while my car is in the body shop having some scratches repaired, with one of the collision detection modules disconnected. Interested to see if that just fixes itself once the car is back together and the battery re-charged. I per-emptivly replaced the 12v battery with an AGM a few months into owning the vehicle.

 

[MakinDoForNow]

It's just a band-aid over the parasitic draw. It's like replacing a 1 gallon bucket with a tiny leak that will drain the bucket in a week with a 2 gallon bucket that has the same leak, so now it takes 2 weeks to drain. All cars have some sort of parasitic draw, the question is what is normal, and what is excessive.

It's interesting for hybrids though because in theory, the 12v battery should only need to turn the relays on for the high voltage battery when you "start" the car, and that's about it. They should last for many years, and be able to operate fine even when significantly under 12v. Except now, Ford and most other manufactures have persistent network services (cellular to FordPass) also drawing on the battery. Then there is the curiosity of why the air conditioning control module is connected to the 12v system, which was supposedly the fix for excessive battery draw.

Couple weeks ago, Car Care Nut (insanely knowledgeable Toyota tech) had a Lexus hybrid in for a weird issue with the HVAC system not operating properly that was traced down a low 12v battery causing an issue with...HVAC computer. Pretty interesting video with good info for hybrid owners on why low voltage on the 12v battery can actually be a serious issue. While it's annoying that car goes into battery save mode, and the "fixes" Ford has made with using AGM batteries and re-programming the AC control module may not really be fixes, gremlins from a low 12v battery can be a lot more serious if left unchecked.



I actually just got my first battery save alert this weekend while my car is in the body shop having some scratches repaired, with one of the collision detection modules disconnected. Interested to see if that just fixes itself once the car is back together and the battery re-charged. I per-emptivly replaced the 12v battery with an AGM a few months into owning the vehicle.

@Darryl I've upped my cognitive helping Brazil nuts to 3/day for a week and been thinking about battery save and getting mav ready to drive. The 12v soc is apparently used to check sensors out at that time with the resistance readings taken with the voltages present at that time. To facilitate proper readings for truck operating status either the 12v needs to furnish power through a voltage stabilizer set to whatever voltage engineering desires (12.4,12.5,...,12.8,?) OR the dcdc converter needs to furnish the stabilized voltage for startup readings. This may also help mediate voltage surges if 12v voltage momentarily exceeds dcdc converter voltages. In any case the voltage stabilizer during operation should be coordinated to follow dcdc down to the baseline minimum operating voltage (say possibly 12.0-1.1). This would be to help with module control issues. Then the charging routines for the 12v battery would still have to be addressed to get it to say 65% in 2 hours 85% in 4 hours or ASAP!.

 

[Darryl]

It's just a band-aid over the parasitic draw. It's like replacing a 1 gallon bucket with a tiny leak that will drain the bucket in a week with a 2 gallon bucket that has the same leak, so now it takes 2 weeks to drain. All cars have some sort of parasitic draw, the question is what is normal, and what is excessive.

It's interesting for hybrids though because in theory, the 12v battery should only need to turn the relays on for the high voltage battery when you "start" the car, and that's about it. They should last for many years, and be able to operate fine even when significantly under 12v. Except now, Ford and most other manufactures have persistent network services (cellular to FordPass) also drawing on the battery. Then there is the curiosity of why the air conditioning control module is connected to the 12v system, which was supposedly the fix for excessive battery draw.

Couple weeks ago, Car Care Nut (insanely knowledgeable Toyota tech) had a Lexus hybrid in for a weird issue with the HVAC system not operating properly that was traced down a low 12v battery causing an issue with...HVAC computer. Pretty interesting video with good info for hybrid owners on why low voltage on the 12v battery can actually be a serious issue. While it's annoying that car goes into battery save mode, and the "fixes" Ford has made with using AGM batteries and re-programming the AC control module may not really be fixes, gremlins from a low 12v battery can be a lot more serious if left unchecked.



I actually just got my first battery save alert this weekend while my car is in the body shop having some scratches repaired, with one of the collision detection modules disconnected. Interested to see if that just fixes itself once the car is back together and the battery re-charged. I per-emptivly replaced the 12v battery with an AGM a few months into owning the vehicle.

Unless a person has had the SSM that says to update the ACCM, they haven't done what is necessary to solve the problem. If that doesn't work, it's one thing. But if that has not been tried, try it before condemning the Maverick. It actually gets rid of the parasitic drain for most vehicles.

 

[Darryl]

I also can get my 12v battery SOC up to 90+, (using car scanner app), after a long (1-2) hr drive.
But I also noticed with my 12v battery volt, (either with car scanner app, or my add on unit “) , it will show normally 14.8-15.1v , but when the 12v SOC reaches 90 % SOC with the cabin fan less than number 5, the system will set the voltage to 12.8v, so it’s discharging out of the battery.
It I turn the cabin fan over 5 with a 12 battery SOC over 90%, it will charge at 14.8v.

Did you have the update performed on the ACCM (air compressor control module) . That has eliminated the excessive drain on MOST vehicles. I recommend it

 

[Neils Bohr]

Did you have the update performed on the ACCM (air compressor control module) . That has eliminated the excessive drain on MOST vehicles. I recommend it

Didn't work on mine.

 

[Darryl]

Didn't work on mine.

This is the actual order of events on one of the Mavericks we had success with. 1. Test battery -passed. 2. Reprogram the ACCM. Perform BMS reset. 3. Release vehicle. 4. Vehicle returned 2 weeks later because it went into deep sleep but didn't die. 5.FULLY charge battery again even though it had passed 2 weeks ago. --failed. 6 replaced battery. Truck is still problem free several months later.
Since then we've had several batteries that initially passed but failed upon retest. Or initially fail but pass the second test. I ALWAYS go by the failed test . Battery will sometimes pass the initial test but fail after a FULL charge

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