Reprogramming Car For A New Battery?

[Corey]

I have a 2007 BMW 335xi.

Today, my battery shit the bed.
I bought a new one and installed it.
Napa and BMW told me I had to take it in and get it reprogrammed…otherwise the car will still think the battery is bad, and it’ll modify performance and features accordingly.

To me, this makes no sense. The car has a battery smart sensor…which should adapt to the car’s battery and learn its state over time.

Am I wrong? Do I need to get it programmed?

Topic

[Konrad]

The sensor is actually a module that contains a temperature sensor and an inductive sensor. It can in no way determine that a battery is actually bad. For example a faulty cell, or low capacity. Think of it as a service reminder for your battery. The inductive sensor measures amperage flowing in and out of a battery, and the temperature sensor measures, yep, the temperature of the battery. Using the total amperage throughput and temperature over time, the module will estimate the condition of the battery’s chemistry. The module does not perform a capacity test or anything of that sort. It is just an estimate based on those two values.

This module is a ‘self preservation’ module and it exists to make sure that when you get in your car in the morning, the vehicle will start. It will ask other modules to not draw power because the battery is weak and that amperage will be needed to start the car. The effects will be implemented in stages based on the assumed condition of the battery. For example, a shut off stage may disable your radio when the engine is not running. The other feature of the module is to provide a low battery warning when you are using power consumers with the engine off and it will ask you to start the engine or else it will start turning things off.

By adapting the new battery you basically reset the service reminder. If you don’t do this, the vehicle will assume that the old worn out battery is still installed. It will not prevent the vehicle from starting.

When you go to your dealer or BMW repair shop, bring with you the battery information. That is the brand, rated amperage in Ah, and there should be a BEM code on the battery.

[Corey]

[quote=”FourRings” post=58316]The sensor is actually a module that contains a temperature sensor and an inductive sensor. It can in no way determine that a battery is actually bad. For example a faulty cell, or low capacity. Think of it as a service reminder for your battery. The inductive sensor measures amperage flowing in and out of a battery, and the temperature sensor measures, yep, the temperature of the battery. Using the total amperage throughput and temperature over time, the module will estimate the condition of the battery’s chemistry. The module does not perform a capacity test or anything of that sort. It is just an estimate based on those two values.

This module is a ‘self preservation’ module and it exists to make sure that when you get in your car in the morning, the vehicle will start. It will ask other modules to not draw power because the battery is weak and that amperage will be needed to start the car. The effects will be implemented in stages based on the assumed condition of the battery. For example, a shut off stage may disable your radio when the engine is not running. The other feature of the module is to provide a low battery warning when you are using power consumers with the engine off and it will ask you to start the engine or else it will start turning things off.

By adapting the new battery you basically reset the service reminder. If you don’t do this, the vehicle will assume that the old worn out battery is still installed. It will not prevent the vehicle from starting.

When you go to your dealer or BMW repair shop, bring with you the battery information. That is the brand, rated amperage in Ah, and there should be a BEM code on the battery.[/quote]

I see.
However, if that’s the case, why did I have to try ~6 times to start my car one morning?
I tried to start it. It cranked 2 times and stopped — all lights on the dash lit up.
Tried again. Cranked once, and all lights on the dash lit up.
I went and checked the battery for a loose connection. All was well. Went in and tried again. It cranked slowly, but started the car.
I made it to work.
At work, the same thing happened.
It finally started, and I drove to NAPA to buy a battery. I figured I’d buy one and install it down my uncle’s garage. However, the car didn’t start. It gave its last breath right there at NAPA after I bought the battery.
Fortunately, my car had tools in the back to replace the battery. So, I replaced it.

But, if the sensor is there to make sure the car starts in the morning…why did it take several attempts?
I would assume that the crank would be immediate, but would cost me to lose every feature the car could offer.

[Konrad]

…and that’s where things start to get complicated. In an ideal situation the vehicle would shut off all power consumers when the ignition is off but things often don’t work out that way. Your battery is either worn out, or it was discharged because there are other issues. The BEM will do whatever it can do maintain enough amperage in the battery to start the car but it is not always successful. I constantly deal with no start issues despite the presence of a BEM. The BEM helps, but it doesn’t make your car immune to low battery charge.

Batteries fail and the BEM can’t reserve a start up charge if there is nothing to store it in. Some fail of old age, and some fail prematurely. The BEM can only predict a battery failure if the battery is working as designed – that means you may or may not get an early warning. We just had a large batch of Moll brand batteries that would barely last a year. In the case of a premature battery failure, the BEM will continue to draw from the battery as though it was healthy. The solution here is simple. Replace the battery and adapt it to the manager so it can begin calculating its condition.

The other type of low charge issue is more complex. The BEM can send requests to other modules to shut off functions or to go into sleep mode so they are not drawing power. Low battery charge issues arise when these modules refuse the requests because of hardware or software issues. They will stay awake and draw power, sometimes intermittently. These types of concerns can be extremely difficult to diagnose and costly to repair.

Hopefully your car just needed a new battery. If you continue to have battery draw issues, it’s time to visit a dealer or other qualified repair facility.

[college man]

see if this link helps.

http://www.justanswer.com/bmw/4qd9b-bmw-335i-replace-change-battery-2007-335i.html

[John B Kobberstad]

http://www.ehow.com/how_7649980_register-bmw-battery.html

Personally I think these vehicles are getting way too complicated for no reason other than to be able to charge more for it initially. Then forcing you to return to the dealer because “Only the dealer has the tool(s) to fix it”

[Matthew]

I personally think its pointless to take it to the dealer. Any auto shop can fix any car if a part can only be obtained from the dealer than the shop will order it from the dealer. Only time i have ever recommended dealer work is if it is for warranty work as having the dealer do everything it costs 3x more than a independent shop.

[Author]

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