Battery

Does anyone know why the battery is so large in this car?

Because it’s a bmw, and they use big batteries

BMW manufactures their own batteries.

Pro tip for those who haven’t experienced them - once they’re dead they can’t be jumped, and you need to replace it with a BMW battery because they have a computer chip that tells the ECU how much charge it has. The cars will pull harder on an older battery to make sure the computer systems have enough juice. This also means the dealer has to install the battery to reset the ECU. Quite costly.

Yes, my new Supra needed a new battery installed prior to delivery. Presumably from people playing with the buttons and switches without actually running the engine. Can't just drop an Optima in there. I was told the batteries are coded to the vin and all. Crazy German engineering

I believe you can code your new battery with BimmerCode yourself. I remember seeing a video on YouTube. I believe it was in a Kies Motorsport video.

So, the batteries can’t be charged back up?

Axix23 said:

So, the batteries can’t be charged back up?

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They can. The issue is voltage is a poor method of determining state of charge. A battery at 12V (6 x 2V cells) may have a 115% capacity or it may have 15% capacity. Only way to know for sure is to put a load on it and measure individual cell outputs over its full discharge curve to cell end voltage.

Lead acid product typically tolerate a certain end voltage for a certain time. Too low of an end voltage and/or at too long a time causes the battery to cannibalize itself. Voltage will recover in charging, but capacity (amp hours) won’t or if it does, will not recover long term.

Batteries also have a set amount of discharges in the depending on a myriad of factors. What BMWs software is doing is running basic diagnostics on the battery along with tracking history. Once it thinks the battery is unreliable, it forces replacement whether it is correct or not. It cannot know as it can’t perform a true load test to IEEE standards or measure cell resistances for additional info. Whether one agrees with this or not, there is a reason for behind BMW doing this. In theory this should significantly decrease the chance of you being stranded with a dead battery.

My background is in industrial batteries and standby systems, but the chemistry is identical, just on a significantly smaller scale for automobiles.

mkivsoopratt said:

Because it’s a bmw, and they use big batteries

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Classic

consultadrone said:

Yes, my new Supra needed a new battery installed prior to delivery. Presumably from people playing with the buttons and switches without actually running the engine. Can't just drop an Optima in there. I was told the batteries are coded to the vin and all. Crazy German engineering

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You're told that because your dealer had no idea what's going on. The code is there to specify the battery type and capacity so the ECU knows what charging profile to use on that specific battery. Nothing to do with the Vin. There are many people running smaller anti-gravity battery or a equivilant Odyssey battery with no problem.

The original BMW lead–acid battery is 26.1kg (57.5lbs) since it has high spec 12V 90Ah.
You may swap it to a lithium one like the LFPO battery, 12V 80Ah is only 9.5kg (20.9lbs).




(Photo credit: CS)

What is the warranty period on the battery?

I thought batteries are big these days because of the start-stop thing.

SilverSupra said:

You're told that because your dealer had no idea what's going on. The code is there to specify the battery type and capacity so the ECU knows what charging profile to use on that specific battery. Nothing to do with the Vin. There are many people running smaller anti-gravity battery or a equivilant Odyssey battery with no problem.

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We’ll see what happens.

In the BMW community, people have installed aftermarket batteries, but usually they get sucked dry in about a year. Don’t know if someone has figured out how to avoid this, but it seems it’s too soon to sound the all clear.

thedude said:

We’ll see what happens.

In the BMW community, people have installed aftermarket batteries, but usually they get sucked dry in about a year. Don’t know if someone has figured out how to avoid this, but it seems it’s too soon to sound the all clear.

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Here's a detailed discussion onbattery coding and the reason why these battery are sucked dry. Different battery type and capacity necessitate different charging voltage and duration.

https://www.e90post.com/forums/showthread.php?t=1338302

Strange... I have a Toyota battery in mine..