How to Change Your BMW Battery Like a Professional


AGM batteries vs. Lead-Acid batteries

Fashionable BMWs have dozens of management modules and tons of of digital actuators, that are elements that management or transfer a mechanism or system. All these electronics devour a major quantity of power, so it’s essential to have a correctly functioning electrical system in any BMW. These autos have gotten more and more technologically superior and may have as much as three batteries, starting from AGM to Lithium-Ion know-how. This text goals to help you in renewing the battery on BMW autos with conventional 12-volt programs. For repairs involving 48-volt or Excessive-Voltage programs, please take your automobile to the closest BMW dealership or licensed unbiased restore facility, as skilled professionals ought to deal with these repairs as a result of presence of hazardous voltages.

What’s a battery?

Let’s begin by understanding what a battery is. A battery basically shops the power generated by the alternator. It primarily begins the inner combustion engine in autos with a single 12-volt battery. Since 2002, BMW autos have used Valve Regulated Lead-Acid (VRLA), also called Absorbent Glass Mat (AGM) batteries. Beforehand, the commonest kind of battery used was Lead-Acid. AGM batteries provide a number of benefits over Lead-Acid batteries, resembling longer service life, elevated beginning reliability in low temperatures, increased energy density, and full sealing. Within the unlikely occasion of injury to the battery casing, no sulphuric acid will escape.

Figuring out the basis reason behind battery discharge

Figuring out the basis reason behind your automobile’s battery discharge is extraordinarily essential. Merely renewing your battery with out figuring out the underlying cause will seemingly end in one other discharged battery shortly after substitute. Think about spending $300 on a brand new battery, putting in it in your storage, after which experiencing one other failure to start out the automotive two weeks later. How irritating would that be? There are various explanation why a battery can discharge, starting from an aged battery to a parasitic draw that depletes the battery whereas the automobile is stationary.

verify for a parasitic draw

Parasitic attracts can happen for varied causes. These embody leaving an inside mild on in a single day, incorrectly putting in aftermarket gadgets resembling radar detectors, cameras, or anti-theft gadgets, leaving the automobile in accent mode, or, in extreme instances, a failed management module that retains the automobile awake. Sure, even BMWs get drained and should enter sleep mode when not in use to forestall electrical system points. When your BMW enters sleep mode, all modules flip off, and the automobile maintains a sure amperage whereas stationary to energy the alarm system, tilt-sensors, ultrasonic inside sensors, and different elements.

If the amperage exceeds this restrict, your battery will discharge, and your automobile will fail to enter sleep mode. This can be a fault that have to be addressed. One solution to verify for a parasitic draw is to shut all of the doorways and lock the automobile. After roughly 15-25 minutes (relying on the model, it might take longer or shorter), the hazard warning mild and begin/cease button illumination ought to flip off, indicating that the automobile has entered sleep mode. If these lights stay illuminated after 25-Half-hour, it’s best to have knowledgeable handle this situation, as finding the supply of the fault(s) may be fairly difficult.

register your new battery

Battery registration is just required in case your BMW has an clever battery sensor, which you’ll be able to establish by a connector and a small black field hooked up to the unfavourable battery terminal. The clever battery sensor is a mechatronic part built-in into the unfavourable battery cable. It comprises a microprocessor that computes and assesses time-critical measured variables. It relays this info to the Engine Management Module (DME/DDE) to regulate the battery cost/discharge currents, monitor terminal voltage, battery temperature, and different essential parameters.

Energy administration, as a subsystem of power administration within the DME/DDE, regulates the ability output of the alternator and the battery charging charges. That’s why it’s important so that you can register your new battery. In a nutshell, battery registration tells the ability administration system that you’ve put in a brand new battery within the automobile. If you happen to change the battery with out registering it, the ability administration system is not going to function correctly. Chances are you’ll even obtain Verify Management messages stating that particular person electrical customers are being switched off or having their energy consumption lowered.

Exchange a BMW Battery – Step-by-step directions


To carry out a battery renewal process, it is strongly recommended that you just go to your nearest BMW dealership or unbiased restore facility. You probably have a number of batteries or discover purple or orange cables in your engine compartment, don’t try this restore. Correctly skilled professionals are required to hold out particular disconnection procedures. Nevertheless, should you determine to deal with battery substitute in your BMW with a single 12-volt battery, comply with these steps:

  1. Find the battery, sometimes within the baggage compartment however probably within the engine compartment on some fashions.
  2. Unlock the automobile utilizing the distant management key button and place the important thing away from the automobile.
  3. Permit the automobile to enter sleep mode, as described beforehand. This step is important to forestall harm to the automobile’s electrical system.
  4. Take away the battery hold-down machine(s) and/or cross member bars that safe the battery to the automobile.
  5. ALWAYS take away the unfavourable battery terminal first. It is suggested that you just wrap the unfavourable battery terminal in a store towel or tape it as much as stop it from unintentionally touching the battery.
  6. Take away the connectors from the crimson energy distribution field hooked up to the constructive battery terminal. Take away the battery vent hose, take away the constructive battery terminal, unlatch the ability distribution field from the battery, and place it to the aspect.
  7. Rigorously take away the battery and set it outdoors the automobile.
  8. In case you are putting in an OEM BMW battery (which is the one battery it’s best to use), take an image of the alpha-numeric characters close to the QC barcode. You will have this later.
  9. Set up the brand new battery, connecting the constructive terminal first. You probably have a torque wrench, tighten it to 5Nm (hand-tight should you don’t). Join the battery vent hose, the ability distribution field connectors, connect the unfavourable battery terminal (utilizing the identical torque because the constructive terminal), and re-install the hold-down machine(s) and cross member bars (hand-tight is enough).
  10. To register the battery substitute, you will want a bi-directional scan software. If you happen to don’t have this software, go to your dealership or unbiased restore facility.

You probably have a bi-directional scan software, start by connecting it to the OBD2 port. Activate the ignition, however maintain the engine off, and find the “register new battery” choice. State whether or not or not you changed the battery with the identical capability and, if requested, kind within the alpha-numeric characters from the image you took of the battery.

Congratulations! You may have efficiently changed your BMW battery and are able to have some enjoyable on the open roads. I extremely advocate buying a battery maintainer for BMWs that aren’t pushed every day. Your BMW dealership’s elements division carries OEM BMW battery maintainers, that are very helpful and simple to make use of.


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