[Dvdman]

I was on the train this morning on my way to work and saw an article in the Sun Times car section about a customer needing a new battery for his BMW. The argument was over the charge of $425. The cost of the battery was $225 but the car had to re learn everything again so that cost an additional $200 plus labor? Does this sound right? Anyone get a new battery at a BMW dealer?

[joec500]

this sounds about right price from a dealer. I would send they your Stewey pic

I think some independent shops have the tools to re-code the battery.

[e93WhiteonRed]

Couldn't you just use a BT tool and do a ECU reset? That causes the ECU to re-learn all of the parameters It needs correct?

[Sniz]

what the hell??

I've disconnected the battery plenty of times, nothing has needed programming as a result.

[Syndicategt]

Hell for that price I'd get a Braille, install it myself, and save $200.

[forza1976]

Originally Posted by Sniz

what the hell??

I've disconnected the battery plenty of times, nothing has needed programming as a result.

+1, not really sure what this is all about. I'd just buy the battery and install it myself?

Guess Mr 5 could chime in and let us know how this went when he converted to that lightweight battery...

[vasillalov]

Ok ok. First of all this does not belong in this forum but rather in the general E90 forum.

Second. This has been heavily discussed.

Third. Our cars no longer use acid-lead based batteries. They are too heavy, produce noxious fumes which makes them unsuitable for the trunk because the air is shared with the passenger cabin and they are plain dangerous if something leaks.

Our cars use AGM (Absorbed Glass Matt) batteries. In essence those types of batteries are completely sealed and do not vent any fumes to the atmosphere. What is most important to know about these batteries is that our ECUs keep track of the charge levels and the remaining battery life of the battery. This information is used to prevent the alternator from overcharging the battery which can shorten their life and in rare cases burst them.

So, if you just disconnected your battery and you reconnected it again, nothing bad will happen because the ECU expects to see the same battery. Once you reconnect your old battery everything matches. The expected charge level is on par and the expected battery life is on par.

When you connect a BRAND NEW battery, the ECU still expects the old one upon reconnect. Therefore it will apply the same charging logic to the new battery, based on the old parameters and this can be detrimental to the new battery.

What needs to be done is the ECU must be told that there is a new battery installed and the ECU will begin relearning the parameters of the new battery.

Is it important: more or less yes. Has it caused problems to people so far: not that I know of.

So yeah, that amount the OP is talking about is completely normal and should not surprise anyone. This is the primary reason why a lot of people do not install an OEM battery after the original one goes bad. It just costs too damn much. People can just get an optima lightweight replacement and be done...

[lyndon_h]

Originally Posted by vasillalov

Ok ok. First of all this does not belong in this forum but rather in the general E90 forum.

Second. This has been heavily discussed.

Third. Our cars no longer use acid-lead based batteries. They are too heavy, produce noxious fumes which makes them unsuitable for the trunk because the air is shared with the passenger cabin and they are plain dangerous if something leaks.

Our cars use AGM (Absorbed Glass Matt) batteries. In essence those types of batteries are completely sealed and do not vent any fumes to the atmosphere. What is most important to know about these batteries is that our ECUs keep track of the charge levels and the remaining battery life of the battery. This information is used to prevent the alternator from overcharging the battery which can shorten their life and in rare cases burst them.

So, if you just disconnected your battery and you reconnected it again, nothing bad will happen because the ECU expects to see the same battery. Once you reconnect your old battery everything matches. The expected charge level is on par and the expected battery life is on par.

When you connect a BRAND NEW battery, the ECU still expects the old one upon reconnect. Therefore it will apply the same charging logic to the new battery, based on the old parameters and this can be detrimental to the new battery.

What needs to be done is the ECU must be told that there is a new battery installed and the ECU will begin relearning the parameters of the new battery.

Is it important: more or less yes. Has it caused problems to people so far: not that I know of.

So yeah, that amount the OP is talking about is completely normal and should not surprise anyone. This is the primary reason why a lot of people do not install an OEM battery after the original one goes bad. It just costs too damn much. People can just get an optima lightweight replacement and be done...

this post should be stickied because it will come up again otherwise

[kaigoss69]

Originally Posted by lyndon_h

this post should be stickied because it will come up again otherwise

It has come up, plenty of times, in the General forum (where this topic belongs). All people need to do is search.

[hun77777]

so for those of you who were running lightweight battery, if they go back to stock battery after, lets say a year or two, they have to have it re-programmed since ecu's expectancy on battery is the lightweight battery? hm... interesting...

[scottp999]

Originally Posted by hun77777

so for those of you who were running lightweight battery, if they go back to stock battery after, lets say a year or two, they have to have it re-programmed since ecu's expectancy on battery is the lightweight battery? hm... interesting...

I did exactly that. The light weight battery was too marginal and I added some electronics so i put the original back in. BMW makes it sound complicated by using the word programming. You are just registering a new battery. It literally takes 2 seconds. In the BT tool you just click the send command button and you are done.

As stated above it is important and can have impacts on the car's electronics if not done.

I think the BMW battery is well worth the money ($215), but put it in yourself, and borrow a BT tool to do the registration if you don't already own one.

Simple as pie with the BT tool (the enthusiast version can do it) Engine Module, Commands, Battery Replacement Adaption, Click Send Button.

Originally Posted by scottp999

... it is the proper procedure on e9x's.

"After fitting a new battery, connect BMW scan tool or equivalent and run service function "Register battery replacement" to notify vehicle power management (software in the engine electronics intelligent battery sensor) that a new battery is fitted in the vehicle.

Without new battery registration, CAS and the vehicle power management does not run properly and this can lead to function limitations, for example: reduction or deactivation of individual consumer functions."


CAS stands for Car Access System and it controls about 14 different functions in the e9x platform.

[hun77777]

u can use bt tools for resetting battery without registering your vin?

[Mr. 5]

This is true.

Originally Posted by vasillalov

Ok ok. First of all this does not belong in this forum but rather in the general E90 forum.

Second. This has been heavily discussed.

Third. Our cars no longer use acid-lead based batteries. They are too heavy, produce noxious fumes which makes them unsuitable for the trunk because the air is shared with the passenger cabin and they are plain dangerous if something leaks.

Our cars use AGM (Absorbed Glass Matt) batteries. In essence those types of batteries are completely sealed and do not vent any fumes to the atmosphere. What is most important to know about these batteries is that our ECUs keep track of the charge levels and the remaining battery life of the battery. This information is used to prevent the alternator from overcharging the battery which can shorten their life and in rare cases burst them.

So, if you just disconnected your battery and you reconnected it again, nothing bad will happen because the ECU expects to see the same battery. Once you reconnect your old battery everything matches. The expected charge level is on par and the expected battery life is on par.

When you connect a BRAND NEW battery, the ECU still expects the old one upon reconnect. Therefore it will apply the same charging logic to the new battery, based on the old parameters and this can be detrimental to the new battery.

What needs to be done is the ECU must be told that there is a new battery installed and the ECU will begin relearning the parameters of the new battery.

Is it important: more or less yes. Has it caused problems to people so far: not that I know of.

So yeah, that amount the OP is talking about is completely normal and should not surprise anyone. This is the primary reason why a lot of people do not install an OEM battery after the original one goes bad. It just costs too damn much. People can just get an optima lightweight replacement and be done...

[IlChengis]

Originally Posted by vasillalov

People can just get an optima lightweight replacement and be done...

Wow, thanks for the info Vasil. Is there a particular lightweight model by Optima that has been tested in our cars? I don't see any lightweight offering on their website.

Thanks,

-Walter

[scottp999]

Originally Posted by hun77777

u can use bt tools for resetting battery without registering your vin?

No. If you have the enthusiast version you can do only 3 cars. I loaned out my 2 extra slots to regional members here, and I would assume others would do the same. I think bavtec will clear vins on the enthusiast verision 1 time free of charge and then there is a cost. You would need to check with them to confirm current policy.