Is your Mini Cooper key fob displaying a low battery warning? You’re not alone. Many Mini Cooper owners face the same issue, especially with models that don’t include the comfort access package. These key fobs are designed to be sealed, with BMW/Mini suggesting you can’t replace the battery yourself. However, as a DIY enthusiast, you know there’s always a way! This guide will walk you through changing the battery in your non-comfort access Mini Cooper key fob, saving you potentially hundreds of dollars on a replacement.
Understanding Your Mini Cooper Key Fob Battery
Mini Cooper key fobs come in different versions. Models with the comfort package often have key fobs with easily replaceable batteries. But if your Mini doesn’t have this feature, you’ll have a sealed fob. These fobs are charged inductively when placed in the designated slot on your dashboard. When you see a warning light on your dashboard, like the one shown below, it’s a clear sign your key fob battery is nearing the end of its life.
Alt text: Dashboard of a Mini Cooper showing a “Replace key battery” warning message.
While your owner’s manual might illustrate a key fob with a removable battery, as seen below, don’t be surprised if yours is different.
Alt text: Diagram from a Mini Cooper owner’s manual depicting a key fob with a user-replaceable battery.
For those of us with the sealed type, the prospect of a costly replacement from the dealership can be daunting. But before you consider that expensive route, let’s explore the DIY solution.
Tools and Materials Needed
Before we begin, gather these essential tools and materials:
- Sharp Knife: A very sharp knife or precision blade is crucial for carefully opening the sealed fob.
- Small Screwdriver or Pry Tool: For gently prying components apart.
- Soldering Iron and Solder: For desoldering the old battery and soldering in the new one.
- Electro Cleaner (Optional): To clean the micro-switches inside the fob.
- Replacement Battery: Panasonic VL2020-1HFN rechargeable battery (ensure correct clips).
- Plastic Glue: To re-seal the key fob casing.
- Clamps: To hold the fob together while the glue dries.
- Dremel or Files (Optional): For fine-tuning the chrome ring fit during reassembly.
- Multimeter (Optional but Recommended): To check battery polarity and connections.
Step-by-Step Guide to Changing the Battery
Step 1: Removing the Chrome Ring
The first step is to carefully remove the chrome ring surrounding the key fob. Many online videos demonstrate this process, often making it look easy. However, be warned: this ring is fragile. Even with extreme care, it can break.
Alt text: Image highlighting the chrome trim ring on a Mini Cooper key fob that needs to be carefully removed.
Use a small pry tool or screwdriver to gently work around the ring, trying to lift it evenly. Patience is key here.
Step 2: Opening the Key Fob Casing
This is arguably the trickiest part. The key fob casing is glued shut and needs to be carefully cut open. A sharp knife is essential for this step. Prioritize safety and secure the fob in a way that prevents injury. Using a vice with wood and rags to hold the fob steady, as shown below, can be a safe approach.
Alt text: Mini Cooper key fob securely clamped in a vice with wooden blocks and cloth for safe opening with a knife.
Carefully score along the seam of the key fob casing, going around its entire circumference. You’ll need to cut deep enough to separate the two halves.
Alt text: Image showing the two parts of the Mini Cooper key fob casing separated after being carefully cut open.
Step 3: Accessing the Circuit Board
Once the casing is open, the internal circuit board should be easily accessible. It might simply lift out.
Alt text: Exposed circuit board of a Mini Cooper key fob after the casing has been opened.
Step 4: Desoldering the Old Battery
The battery is soldered onto the circuit board. Carefully desolder the old battery from the board using a soldering iron.
Alt text: Close-up of the desoldering process to remove the old battery from the Mini Cooper key fob circuit board.
Step 5: Identifying and Ordering the New Battery
The battery is a Panasonic VL2020-1HFN rechargeable battery. Note the specific clips attached to the battery, especially their angle. The + and – clips might be 180 degrees apart, but other variations exist (90 or 120 degrees).
Alt text: Panasonic VL2020-1HFN rechargeable battery, the standard replacement for Mini Cooper key fobs.
When ordering a replacement online, carefully check that the clips match your old battery.
Step 6: Soldering the New Battery
Solder the new battery onto the circuit board. Double-check the polarity (+ and -) before soldering. Ensure the battery sits at the correct height above the board for proper reassembly.
Alt text: Side-by-side comparison of a new replacement battery and the old, original battery from the key fob.
Cautionary Tale: Even experienced DIYers can make mistakes. As seen below, it’s possible to solder the battery on the wrong side of the circuit board!
Alt text: Example of a DIY mistake: Battery incorrectly soldered on the wrong side of the Mini Cooper key fob circuit board.
Double-check your work and correct any errors before proceeding.
Step 7: Reassembling the Key Fob
Carefully reassemble the key fob. Apply plastic glue to the edges of the casing and clamp the two halves together for at least 24 hours to allow the glue to dry and harden.
Alt text: Reassembled Mini Cooper key fob clamped together while the plastic glue is drying.
Refitting the chrome ring can be fiddly, especially if it was damaged during removal. You might need to use a Dremel or files to reshape the key fob body slightly for a proper fit.
Alt text: Close-up showing the chrome ring being carefully reattached to the reassembled Mini Cooper key fob.
Step 8: Testing and Final Checks
Once reassembled, test your key fob to ensure it’s working correctly. Check if the car locks and unlocks remotely and that the key is recognized by the ignition.
Alt text: Image of the successfully repaired and fully functional Mini Cooper key fob after battery replacement.
Conclusion
Changing the battery in your Mini Cooper key fob, even the sealed type, is a manageable DIY task. It requires patience, careful work, and some basic soldering skills. By following these steps, you can save yourself a significant amount of money compared to dealership replacement costs and gain the satisfaction of fixing it yourself. Remember to always prioritize safety when using sharp tools and soldering equipment. Happy DIY-ing!
