Is your Mini Cooper key fob displaying a low battery warning? Don’t rush to the dealership just yet! While Mini Cooper key fobs are often sealed units without readily accessible battery compartments, replacing the battery yourself is entirely possible with a little patience and the right approach. This guide will walk you through the process of replacing the battery in your non-comfort access Mini Cooper key fob, saving you potentially significant costs and keeping you on the road.
You might be wondering why your key fob battery is draining, especially if it’s designed to recharge. Mini Cooper key fobs, even those without comfort access, typically use inductive charging when placed in the designated slot in your dashboard. However, like all rechargeable batteries, they have a lifespan. Over time, the battery’s capacity diminishes, leading to the dreaded low battery warning.
If you’re seeing a warning light on your dashboard like this:
It’s a clear sign that your key fob battery is nearing the end of its life. While Mini Cooper offers key fobs with easily replaceable batteries in their “comfort access” package, many models come with sealed fobs, seemingly designed to prevent DIY battery changes.
But don’t worry, with this step-by-step guide, you can confidently tackle this DIY project. Let’s get started!
What You’ll Need
Before you begin, gather these essential tools and materials:
- New Battery: Panasonic VL2020-1HFN rechargeable battery (ensure the clips are correctly oriented – 180 degrees apart as in the original example, but double-check against your old battery).
- Small, Sharp Knife or Precision Blade: For carefully separating the key fob casing.
- Small Flathead Screwdriver or Pry Tool: To assist in prying open the casing.
- Soldering Iron and Solder: For desoldering the old battery and soldering in the new one.
- Electro Cleaner Spray (Optional): To clean the micro-switches inside the fob.
- Plastic Glue: To reassemble the key fob casing.
- Clamps or Strong Tape: To hold the casing together while the glue dries.
- Dremel or Small Files (Optional): For refining the casing edges after opening (if needed).
- Multimeter (Optional but Recommended): To check battery polarity and voltage.
- Safety Glasses: To protect your eyes during disassembly.
- Anti-Static Wrist Strap (Optional): To prevent electrostatic discharge damage to the circuit board (especially in dry environments).
Step-by-Step Guide to Battery Replacement
Here’s a detailed walkthrough of how to replace your Mini Cooper key fob battery:
Step 1: Examine Your Key Fob
Familiarize yourself with your Mini Cooper key fob. This guide applies to the sealed type, which looks like this:
Note the chrome ring and the seam running around the side of the fob – this is where we’ll need to carefully separate the casing. Also, be aware that your key fob contains a mechanical key for emergency access:
Step 2: Removing the Chrome Ring
The first step is to remove the chrome ring surrounding the key fob. This is often held in place with small clips and adhesive. Attempt to gently pry it off using a small flathead screwdriver or pry tool. Be extremely cautious as this ring is fragile and can easily break:
Work slowly and patiently around the ring to minimize damage. Even with care, some breakage is possible.
Step 3: Opening the Key Fob Casing
This is the trickiest part. The key fob casing is glued shut and needs to be carefully cut open along the seam. Use a sharp knife or precision blade. Secure the key fob firmly (using a vice and soft cloths as shown in the original article is a good method for safety) to avoid injury and to get a stable cutting surface.
Carefully score along the seam line repeatedly, gradually cutting deeper into the plastic. Work your way around the entire circumference of the fob. Patience is key here. Avoid rushing, which could lead to damaging the internal components.
Once you’ve cut deep enough, gently pry the two halves of the casing apart using your flathead screwdriver or pry tool.
Step 4: Accessing the Circuit Board and Battery
With the casing open, the circuit board should be easily accessible. In most cases, it will lift out freely.
Locate the battery on the circuit board. It’s usually a small, button-shaped rechargeable battery, like the VL2020.
Step 5: Desoldering the Old Battery
Carefully desolder the old battery from the circuit board. You’ll need a soldering iron to melt the solder joints connecting the battery terminals to the board.
Take note of the battery’s orientation (+ and – terminals) before removing it. This is crucial for correctly installing the new battery.
Step 6: Soldering the New Battery
Now, solder the new VL2020 battery into place. Ensure you match the polarity correctly – the positive (+) and negative (-) terminals must align with the markings on the circuit board.
Double-check the orientation before soldering. In the original example, the battery was initially soldered on the wrong side, requiring rework!
Make sure the battery sits flush and securely on the circuit board, at the correct height for proper reassembly.
Step 7: Reassembling the Key Fob
Carefully place the circuit board back into the key fob casing halves. Ensure the mechanical key locking mechanism is correctly positioned for proper operation. Test the mechanical key insertion and removal to confirm it’s working smoothly.
Step 8: Gluing the Casing Back Together
Apply a thin bead of plastic glue to the edges of one half of the key fob casing. Carefully align and press the two halves together.
Use clamps or strong tape to hold the casing firmly together while the glue dries completely, usually for 24 hours as recommended in the original guide.
Step 9: Refitting the Chrome Ring
Once the glue is fully cured, refit the chrome ring. This can be fiddly, especially if the casing edges are not perfectly aligned after cutting. You might need to use a Dremel or small files to carefully refine the edges of the plastic casing to ensure a snug fit for the chrome ring. Be patient and work gradually to avoid damaging the plastic.
Conclusion
Congratulations! You’ve successfully replaced the battery in your sealed Mini Cooper key fob. This DIY approach can save you a considerable amount compared to dealership replacement costs. While it requires some careful work and basic soldering skills, it’s a manageable task for most DIY enthusiasts.
Remember to take your time, be patient, and double-check each step. If you are uncomfortable with soldering or disassembling delicate electronics, it might be wise to seek professional help. However, for those willing to try, replacing your Mini Cooper key fob battery at home is a rewarding and cost-effective solution to keep your Mini running smoothly.
