In the last blog post, our BMW M240i found its way from the Copart marketing centre in Giessen via Bochum to the Marx Performance workshop.
So after just under 50,000 kilometres and 3 years, it’s okay for a battery to give up the ghost. This is what happened to the battery in our 2 series and the vehicle had to be bypassed every time. After charging the battery didn’t help either, I decided to replace it with a new one.
We recorded the whole project on video and publish it on our YouTube channel every Wednesday and Sunday at 19:30. Feel free to check it out!
Part 3: Replacing the Battery and coding the battery management
No sooner said than done: I bought a battery of the same type from my local car parts dealer and drove back to the workshop full of enthusiasm.
Even as an average mechanic, the installation went very smoothly. First remove the floor plate in the boot, then remove the two screws that hold the retaining clip above the battery and finally loosen the retaining plate to the right of the battery, which is also held in place by a screw.
It’s about the details
As the battery sits in the boot and fumes may be produced during charging, it must be vented. This step is not necessary for batteries installed in the engine compartment. In the BMW 2 Series, you will find the venting hose on the left under the positive terminal. You can simply pull this hose out of the battery and then reconnect it to the new battery. Proceed in exactly the same way with the terminals. First disconnect the positive terminal from the battery, then the negative terminal.
Removing the battery is a bit of a feat, as it weighs about 25 kilograms. I’ve already noticed that car batteries are relatively heavy in my previous car repair adventures, but this AGM battery (you need this type for vehicles with automatic start/stop) is a real heavyweight!
Once the old battery is removed, you can install it in reverse order: first connect the vent on the left side, then screw on the positive terminal. As soon as you connect the negative terminal – and you have a working, charged battery – the boot light should come on and other functions in the car should come to life.
The final task now is to re-secure the battery via the fuse plate on the right-hand side and then put the bracket on and tighten the two screws again.
That was the manual part. It is now important for vehicles with an IBS (Intelligent Battery Sensor) to which our M240i belongs, to carry out a coding or registration of the new battery.
Why do we have to do this? The battery management system in the car ensures that the battery is always charged according to its age and thus its wear. So if the battery loses 50% of its capacity over the years, the alternator will only charge the battery to 50%. If a new battery is installed without re-registering, this new battery will also only be charged to 50% or less over time. The system calculates the wear based on the time driven, number of starts, number of short trips and other parameters.
It is very likely that your new battery will not last as long as promised without an adjustment of the IBS, because it is never fully charged.
It is therefore imperative that you pay attention to the coding!
We did this coding via the Carly app, which has a simple workflow for this task.
After we have adjusted the hardware and software, we can enjoy our new energy source and drive the next 50,000 kilometres without any worries.
In the next episode, we take a closer look at the damage to the vehicle!
We look forward to see you in Part 4!