Is your Mini Cooper displaying a low key battery warning? If you own a Mini without the comfort access package, you might be facing the challenge of a sealed Mini Key Fob. Unlike key fobs with replaceable batteries, these sealed units are designed by BMW/Mini to discourage DIY battery changes. However, replacing the battery yourself is not only possible but also a cost-effective alternative to purchasing a new key fob. This guide, inspired by a resourceful DIY enthusiast, will walk you through the process of replacing the battery in your sealed mini key fob, saving you potentially hundreds of dollars.
Many modern car key fobs, often called mini key fobs due to their compact size, utilize rechargeable batteries that replenish when inserted into the car’s dashboard or center console. These batteries, however, do have a lifespan and will eventually require replacement. While some mini key fobs are designed for easy battery swaps, others, like those in certain Mini models without the comfort package, are sealed, leading owners to believe professional replacement is the only option.
This guide will demonstrate that with patience and careful execution, you can successfully replace the battery in your sealed mini key fob. It’s a practical DIY project that empowers you to maintain your vehicle and avoid unnecessary expenses.
Understanding Your Mini Key Fob
Before we begin, it’s important to understand the type of mini key fob you have. As mentioned, Mini Coopers with the comfort package typically come with key fobs that have a removable battery compartment, making battery replacement straightforward. However, if your mini key fob looks like the one pictured below, it’s likely a sealed unit requiring a different approach.
Image: Dashboard warning indicating a low battery in the Mini Cooper key fob.
For those with sealed mini key fobs, don’t worry! This guide provides a detailed, step-by-step process to safely open your key fob and replace the battery.
Tools You’ll Need for Mini Key Fob Battery Replacement
To perform this mini key fob battery replacement, you’ll need a few common tools:
- Small, sharp knife or precision blade: Essential for carefully separating the glued halves of the key fob.
- Small flat-head screwdriver or plastic pry tool: Helpful for prying open the key fob and removing the circuit board.
- Soldering iron and solder: Required to desolder the old battery and solder in the new one.
- New VL2020-1HFN Rechargeable Battery: This is the specific battery type commonly found in these mini key fobs. Ensure you purchase one with the correct connector clips (180 degrees apart).
- Electro cleaner spray (optional): For cleaning the micro-switches on the circuit board.
- Plastic glue or epoxy: To re-seal the key fob casing.
- Clamps or rubber bands: To hold the key fob halves together while the glue dries.
- Dremel or small files (optional): May be needed for minor adjustments when reassembling the chrome ring.
- Multimeter (optional but recommended): To check battery polarity and voltage.
- Safety Glasses: To protect your eyes during disassembly and soldering.
Step-by-Step Mini Key Fob Battery Replacement
Now, let’s proceed with the battery replacement for your mini key fob.
Step 1: Removing the Chrome Ring (Handle with Care)
The first step is to carefully remove the chrome ring surrounding the mini key fob. This ring is delicate and can break easily. Using a small, flat tool or your knife tip, gently pry around the edges of the ring to loosen it. Work slowly and patiently to minimize the risk of damage.
Image: A detailed view of the Mini key fob highlighting the chrome ring that needs to be carefully removed.
Caution: Be extremely careful during this step as the chrome ring is fragile. Even with caution, there’s a risk of breakage, as experienced in the original guide.
Step 2: Opening the Sealed Key Fob Casing
This is the trickiest part. The mini key fob casing is glued shut and needs to be carefully cut open. Use a sharp knife and gently score along the seam line that runs around the side of the key fob. Multiple passes with light pressure are better than trying to force it open with one deep cut.
Image: Demonstrating the process of carefully cutting along the seam of the Mini key fob to separate the glued halves.
Safety First: Ensure you have a firm and safe grip on the mini key fob while cutting to avoid injury. Using a vise with soft jaws or a similar stabilizing method can be helpful.
Once you’ve cut deep enough around the entire circumference, you should be able to gently pry the two halves of the mini key fob apart.
Image: The Mini key fob opened, showing the circuit board and battery inside.
Step 3: Accessing the Circuit Board and Battery
With the casing open, the internal circuit board should be easily accessible. Carefully lift it out of the casing.
Image: The circuit board of the Mini key fob, now removed from the outer casing.
You’ll see the battery soldered onto the circuit board. Note the orientation of the battery and the positive (+) and negative (-) terminals before proceeding.
Step 4: Desoldering and Replacing the Battery
Using your soldering iron, carefully desolder the old battery from the circuit board. Take your time and avoid applying excessive heat, which could damage the circuit board.
Image: The process of desoldering the old battery from the circuit board of the Mini key fob.
Once the old battery is removed, take your new VL2020-1HFN battery and solder it into place, ensuring correct polarity (+ and -). Double-check that the battery sits securely and at approximately the same height as the original.
Image: A close-up of the new VL2020-1HFN battery, highlighting its specifications and connector clips.
Important: Ensure you solder the new battery on the correct side of the circuit board and with the correct polarity. Mistakes can happen, as shown in the original guide, so pay close attention!
Image: Side-by-side comparison of the new and old batteries, emphasizing the importance of correct size and connector type.
Step 5: Reassembling the Mini Key Fob
Before gluing the casing back together, test the mini key fob to ensure it’s working. Insert the key into your Mini and check if the low battery warning is gone and the key functions correctly.
If everything works, carefully align the two halves of the mini key fob casing and apply plastic glue or epoxy to the seam. Clamp or use rubber bands to hold the halves firmly together while the glue dries completely (usually 24 hours).
Image: The two halves of the Mini key fob being reassembled and glued back together.
Step 6: Reattaching the Chrome Ring and Final Touches
Once the glue is dry, carefully attempt to reattach the chrome ring. This can be fiddly, and as mentioned earlier, the ring may have been damaged during removal. If necessary, use a Dremel or small files to slightly adjust the edges of the key fob casing to help the chrome ring fit back in place.
Image: The fully repaired Mini key fob, with the new battery installed and the chrome ring reattached.
Tips and Warnings
- Patience is key: Take your time and work carefully throughout the process.
- Sharp tools are necessary but handle with caution: Always cut away from yourself and use a stable work surface.
- Double-check battery polarity: Incorrect polarity can damage the circuit board.
- Ensure correct battery type: Use VL2020-1HFN or the exact replacement specified for your mini key fob.
- Test before gluing: Always test the key fob functionality before permanently sealing the casing.
- Consider professional help if unsure: If you are uncomfortable with soldering or opening electronic devices, seek assistance from a professional car key repair service.
Conclusion
Replacing the battery in a sealed mini key fob might seem daunting, but with this step-by-step guide, it becomes a manageable DIY task. By following these instructions, you can save yourself the cost of a new key fob from the dealership and gain the satisfaction of repairing it yourself. This project not only extends the life of your mini key fob but also empowers you with valuable DIY skills for car maintenance. Remember to always prioritize safety and take your time, and you’ll be back on the road with a fully functional mini key fob in no time!
