Battery Replacement Query

[raptert]

Hi,

I have next to no knowledge with cars.

My car recently had an issue with the battery so I bought a new battery and got a mechanic to replace it.

Obviously because the car was disconnected I had to reset the date/time etc but the mechanic didn’t do anything else.

Having a Quick Look recently when checking over replacing batteries in cars, I have seen that maybe something might need to be coded or something to register the new battery? Should my mechanic have done this because after installing the new battery they didn’t do anything further.

The car is a 2011 BMW 125i (E82).

Thanks in advance!

[RockCrusher]

Think there is more to BMW battery replacement than just setting date/time afterwards.

Link:

https://www.bimmer-tech.net/blog/ite...d-registration

[ctcarbonari]

Originally Posted by RockCrusher

Think there is more to BMW battery replacement than just setting date/time afterwards.

Link:

https://www.bimmer-tech.net/blog/ite...d-registration

^Nice link^

To clarify a bit there's (2) processes. When you replace the battery "in kind", i.e. the same Ah rating and specs as your previous battery then you'll only need to register the new one. If you replace the battery with a higher or lower capacity (different Ah rating) then you'll need to Code the battery.

In layman's terms:
Registration - Tells the car "hey, this is a new battery. Charge it up accordingly"

Coding - Tells the car "hey, this is a different rated battery. Change the rate at which you're charging it up"


Usually only registration is required and does not need to be performed immediately after installation but should be done sooner, rather than later, to maintain a longer lifespan.

Both processes are VERY simple to do with most scan tools that are made for BMWs. For the cost of paying someone else to register your battery you'll be able to buy a scan tool and do it yourself. Then you'll have an invaluable tool that will help you in the future (read/clear error codes, reset service indicators, dispaly sensor values, etc)

[BMWCCA1]

I still contend that neither procedure is truly necessary. If the car is so "smart" that it requires being told whether or not a battery was replaced in order to charge it properly, how smart can it really be? How does the charging system differentiate between the battery your car came with and that same battery five-years later? I have the ability to "register" a BMW battery and still think it's basically bunk. I put a new battery in my wife's E90 when there were parts shortages due to the Pandemic. I went with one of the higher-output batteries at the dealership where I worked. One of the techs told me they'd have to re-program the car for the new type of battery. When they went to do it the existing hardware in the 2008 BMW didn't offer a selection that fit with the new battery. They told me not to worry about it. Several years later and it hasn't seemed to make any difference!

[///MPhatic]

The battery should always be registered, just in case.

This is because the older the battery gets the more charge it loses during use, and thus the more charge the DME (ECU) sends to it.

It's possible that with some BMW's the DME could over-charge the battery, therefore shortening its life.

However, supposedly the DME is constantly checking the voltage so there shouldn't be a possibility of over-charging.

This is why I say err on the side of caution and register the battery.

[RockCrusher]

Originally Posted by ctcarbonari

^Nice link^

To clarify a bit there's (2) processes. When you replace the battery "in kind", i.e. the same Ah rating and specs as your previous battery then you'll only need to register the new one. If you replace the battery with a higher or lower capacity (different Ah rating) then you'll need to Code the battery.

In layman's terms:
Registration - Tells the car "hey, this is a new battery. Charge it up accordingly"

Coding - Tells the car "hey, this is a different rated battery. Change the rate at which you're charging it up"


Usually only registration is required and does not need to be performed immediately after installation but should be done sooner, rather than later, to maintain a longer lifespan.

Both processes are VERY simple to do with most scan tools that are made for BMWs. For the cost of paying someone else to register your battery you'll be able to buy a scan tool and do it yourself. Then you'll have an invaluable tool that will help you in the future (read/clear error codes, reset service indicators, dispaly sensor values, etc)

I'm woefully ignorant of battery replacement in my BMWs. Never had to replace one. Just haven't owned a BMW long enough yet.

While I have replaced batteries in other cars it was just a matter of disconnecting the old battery and lifting it out of the battery box and dropping in a new battery and reconnecting it. In fact I was able to do this quick enough I don't recall having to bother with resetting the date/time or the radio presets. In one car the steering angle sensor even reset itself on the short (~1 mile) drive to the dealer.

But when the time comes I'll have the battery replaced by the dealer service department and all the necessary registration/coding done.

[BMWCCA1]

Originally Posted by ///MPhatic

The battery should always be registered, just in case.

This is because the older the battery gets the more charge it loses during use, and thus the more charge the DME (ECU) sends to it.

It's possible that with some BMW's the DME could over-charge the battery, therefore shortening its life.

However, supposedly the DME is constantly checking the voltage so there shouldn't be a possibility of over-charging.

This is why I say err on the side of caution and register the battery.

As I implied, if the system is smart enough to adjust the charge rate as the original battery ages, why assume it's not smart enough to know what is required when a new battery is installed? You aren't required to "re-register" your original battery every year, are you? It just doesn't make any sense.

[zx10guy]

Originally Posted by BMWCCA1

I still contend that neither procedure is truly necessary. If the car is so "smart" that it requires being told whether or not a battery was replaced in order to charge it properly, how smart can it really be? How does the charging system differentiate between the battery your car came with and that same battery five-years later? I have the ability to "register" a BMW battery and still think it's basically bunk. I put a new battery in my wife's E90 when there were parts shortages due to the Pandemic. I went with one of the higher-output batteries at the dealership where I worked. One of the techs told me they'd have to re-program the car for the new type of battery. When they went to do it the existing hardware in the 2008 BMW didn't offer a selection that fit with the new battery. They told me not to worry about it. Several years later and it hasn't seemed to make any difference!

The system isn't detecting the state of the battery nor checking to see the type of battery it has. It's about letting the DME know so it can perform the proper charge cycle based on preprogrammed curves/parameters. It's the same thing as the sensor used in the CBS for when you should change the oil. It's very rudimentary and not meant to be as accurate as having an oil analysis done in real time.

Frankly, I think BMW just overcomplicates things as things were fine before these variable charging curves showed up. Being that this is a thing with my E82, I prefer to do it the "right" way and not risk any possible issues with shortening the battery life of a new battery. That said, I haven't looked but I'm sure my scan tool has that functionality so it's no issue on my part to get the coding/registration done to perform a battery change "properly."

[ctcarbonari]

Originally Posted by RockCrusher

I'm woefully ignorant of battery replacement in my BMWs. Never had to replace one. Just haven't owned a BMW long enough yet.

I think you're on to something ^here^ @ just don't own a BMW long enough to have to deal with any of the issues.

I agree with the over complicating comments (where's my oil dipstick? why do I have to crawl underneath the car with an allen wrench to mechanically disengage my transmission?).

However, my current original battery is now 10 years old. Maintains a nearly constant 80% state of charge and still load tests in the "good" range. That long of a lifespan is much more of a testament as to how well the car charges and maintains the battery vs the manufacturer brand of the battery itself. My Indy says that they pull out 10+ year old batteries all the time.
(Replacing my battery is on the PM list for this winter - hope I haven't just jinxed myself by talking about it...lol)

[///MPhatic]

Originally Posted by BMWCCA1

As I implied, if the system is smart enough to adjust the charge rate as the original battery ages, why assume it's not smart enough to know what is required when a new battery is installed? You aren't required to "re-register" your original battery every year, are you? It just doesn't make any sense.

The system could have been better for sure, but it's based on probabilities instead of real-time data.