Is battery management module necessary?

[CrazyBattleGoose]

Sorry if this is in the wrong place, I've searched the forum and haven't found an answer. I'll also say this is my first car made after 1990 if that's not apparent by my question.

My battery died today and after jumping the car to test it at autozone found the battery was completely dead and needed replacement. The negative terminal was so corroded it had practically welded itself to the battery post. Trying to get it off pulled the post off the battery before the terminal came off. Time was an issue so I just bought a generic battery cable (they didn't have an oem battery management module)and ran that from the new battery to ground and left the module plug-in tucked out of the way.

Car started right up, no check engine light, no warnings, nothing. Is it necessary? I found the oem part is $150, and I'm just hesitant after the $250 I just spent on the battery and new connector. I mean, none of my older cars needed it to protect the battery, are newer cars "rougher" on batteries? Can I get by with this for a while? Forever? Or "don't start the car again, replace asap"?

Any help is appreciated, thanks

 

[TyphoonFiST]

Sorry if this is in the wrong place, I've searched the forum and haven't found an answer. I'll also say this is my first car made after 1990 if that's not apparent by my question.

My battery died today and after jumping the car to test it at autozone found the battery was completely dead and needed replacement. The negative terminal was so corroded it had practically welded itself to the battery post. Trying to get it off pulled the post off the battery before the terminal came off. Time was an issue so I just bought a generic battery cable (they didn't have an oem battery management module)and ran that from the new battery to ground and left the module plug-in tucked out of the way.

Car started right up, no check engine light, no warnings, nothing. Is it necessary? I found the oem part is $150, and I'm just hesitant after the $250 I just spent on the battery and new connector. I mean, none of my older cars needed it to protect the battery, are newer cars "rougher" on batteries? Can I get by with this for a while? Forever? Or "don't start the car again, replace asap"?

Any help is appreciated, thanks

There is a reason it was engineered that way....the car is a CAN bus system and there are twice as many electronics in cars now. Most newer cars as far as I'm concerned should get AGM batteries from the factory.....some do. I would get the correct part ordered and roll the current setup until the new part arrives. Your car....your choice.

Sent from my SM-N975U1 using Tapatalk

 

[XR650R]

I don't know if it's the same unit used in the base Fiesta, but if it is, you might be able to find a usable one off a junker fairly cheap.

Like Ty said, there are a million different little electronic gizmos in modern cars. It's best to keep them happy.

Now you know. Keep an eye on all your battery shit and keep it clean.

 

[HardBoiledEgg]

No way everything works without it

 

[CrazyBattleGoose]

Thanks guys for the responses, part ordered. I'll keep a closer eye on it this time

 

[contemplative_shrimp]

Bringing this old thread to life...

If there are no error codes but the negative terminal cable and sensor are heavily corroded - should I just give it a cleaning and use, or purchase a new one? Seems like this cable is backordered at most shops, not to mention costs $90-100 brand new. At the moment it looks like my car is out of commission minimum a week if I replace that cable. I just replaced a dead battery (3.5 years oem) so am wary the sensor corrosion might have contributed.

 

[Dialcaliper]

Battery management module is needed - Ford already put a quite complicated system in that does two things:

1) Doesn’t charge the battery to full voltage which helps prolong battery life
2) Controls the Battery charging to lower load periods and less during warmup for better fuel economy and emissions
3) Has a low voltage cutoff that shuts off the battery when it is low until it’s really needed to restart the car (much like the aftermarket ones you can buy), which helps with the high parasitic loads in modern cars.

Without the battery module, that battery will charge and discharge only based on the natural voltage curve, which is fine for an older car, but will result in lots of heavy discharges, which will wear out a battery much more quickly.

 

[Capri to ST]

Battery management module is needed - Ford already put a quite complicated system in that does two things:

1) Doesn’t charge the battery to full voltage which helps prolong battery life
2) Controls the Battery charging to lower load periods and less during warmup for better fuel economy and emissions
3) Has a low voltage cutoff that shuts off the battery when it is low until it’s really needed to restart the car (much like the aftermarket ones you can buy), which helps with the high parasitic loads in modern cars.

Without the battery module, that battery will charge and discharge only based on the natural voltage curve, which is fine for an older car, but will result in lots of heavy discharges, which will wear out a battery much more quickly.

That's interesting, it does sound like quite a useful and well thought out system. I'm glad to know that our car is have it.

 

[WannabeST]

For what it's worth. A lot of people delete this system on the S550 mustangs, particularly on track because there is cases of the system being stuck on charging and it swells oem and aftermarket batteries.

 

[contemplative_shrimp]

This is what my cable looked like when I replaced the battery (3.5 years, 25k miles). I figure I should get a new one just in case, though I didn't have any obvious electrical issues or codes.

 

[XR650R]

You can probably just clean it up.

 

[Ton]

This is what my cable looked like when I replaced the battery (3.5 years, 25k miles). I figure I should get a new one just in case, though I didn't have any obvious electrical issues or codes.

View attachment 58196

Looks like it wasn’t torque down properly

 

[Dialcaliper]

For what it's worth. A lot of people delete this system on the S550 mustangs, particularly on track because there is cases of the system being stuck on charging and it swells oem and aftermarket batteries.

Don’t know about OEM batteries, but I could definitely imagine some issues might crop up pairing it with a small lower capacity racing battery. Overheating the little module with high under hood temperatures probably wouldn’t help either.

 

[M-Sport fan]

This is what my cable looked like when I replaced the battery (3.5 years, 25k miles). I figure I should get a new one just in case, though I didn't have any obvious electrical issues or codes.

View attachment 58196

Was that original battery over charging at all??

Was the casing swollen on the sides, or bulging at all when you replaced it?

That terminal/module almost looks COOKED, but I guess that could just be the 'normal' acid erosion of a flooded lead acid battery.

 

[contemplative_shrimp]

Was that original battery over charging at all??

Was the casing swollen on the sides, or bulging at all when you replaced it?

That terminal/module almost looks COOKED, but I guess that could just be the 'normal' acid erosion of a flooded lead acid battery.

No indication that anything was wrong with the battery, other than the visual corrosion of the terminal. Battery was 3.5 years when it died so I don't know if it was premature due to this condition, or if that's just how long the OEM battery might last in this car. I've seen another user post their battery cable looking very similar to this in a different post.

I've had issues (which seem to be common) with the terminal getting corroded. Cleaned everything with baking soda maybe 1-1.5 years ago, which left the terminal looking an odd color/finish - I'm assuming since then the continual acid erosion has caused this "burnt" appearance.

 

[M-Sport fan]

Yeah, that's another reason why I spend the extra coin and only buy AGM batteries now.
Both of my cables are in factory perfect condition, even after 7 years of ownership.

 

[fun with fisting]

Anybody know the part number for the pigtail/connector that plugs onto that battery management module from the wiring loom?

To replace my negative terminal and sensor, I will also need to cut out and splice on a new plug.

Thanks

 

[Intuit]

We're supposed to reset the charging system following a battery swap or charge.
https://www.fiestastforum.com/threads/battery-monitoring-system.25904/post-478335

https://www.fiestastforum.com/threads/agm-battery-concerns.24120/

 

[Intuit]

Anybody know the part number for the pigtail/connector that plugs onto that battery management module from the wiring loom?

To replace my negative terminal and sensor, I will also need to cut out and splice on a new plug.

Thanks

Call the parts center at your local Ford dealer. They're often very helpful. Just make sure they understand it's an ST and not one of the other trim levels.

 

[fun with fisting]

Call the parts center at your local Ford dealer. They're often very helpful. Just make sure they understand it's an ST and not one of the other trim levels.

On the phone, dealer parts center gave me just 14S411, which now looking online appears to be an incomplete PN as I'm seeing variations.

I'm thinking DU2Z-14S411-AZB might be the one. I can't even tell what the connector looked like anymore because it's so badly deteriorated. I tried unplugging it from the sensor and the thing literally turned to mush in my hands and wouldn't come unplugged.