Is your 2011 Mini Cooper displaying a low key battery warning? Don’t rush to the dealership just yet! Like many Mini owners, you might discover that your key fob is designed as “sealed,” with BMW/Mini suggesting professional battery replacement. However, with a bit of careful DIY spirit, you can tackle this yourself and save potentially significant costs. This guide will walk you through replacing the battery in your 2011 Mini Cooper key fob, even if it’s the seemingly non-replaceable type.
Many Mini Cooper models, especially those without the comfort access package, come with key fobs that appear to be sealed shut. These fobs are designed to charge inductively when placed in the dashboard slot. When that “low battery” warning pops up on your dash, it’s a clear sign the rechargeable battery inside your key fob is nearing the end of its lifespan.
Before we dive into the repair, let’s understand what we’re dealing with. The term “key fob” itself is quite interesting. It’s believed to originate from “watch fobs,” decorative ornaments attached to pocket watches dating back to the late 19th century. In the context of car keys, it represents a compact, often feature-rich device that controls your vehicle’s functions remotely.
Now, back to your Mini Cooper. If your model includes the comfort package, you’re in luck! These key fobs typically have a replaceable battery compartment, making battery changes straightforward.
However, if your 2011 Mini Cooper, like many, lacks the comfort package, you’re likely facing a sealed key fob. Dealership replacements can be expensive, sometimes costing as much as a significant fraction of what an older car is worth. The good news is, with patience and the right approach, you can replace the battery yourself.
Step-by-Step Guide to 2011 Mini Cooper Key Fob Battery Replacement
This guide details how to open your sealed Mini Cooper key fob and replace the battery. Remember to work carefully and patiently to avoid damaging your key fob.
Tools and Materials You’ll Need:
- Small, sharp knife or precision blade
- Small flat-head screwdriver or prying tool
- Soldering iron and solder
- Desoldering braid or pump (optional, but helpful)
- New Panasonic VL2020-1HFN rechargeable battery (ensure correct clip orientation)
- Plastic glue or epoxy
- Clamps or rubber bands
- Multimeter (optional, but recommended for polarity check)
- Electro cleaner spray (optional, for micro-switches)
Step 1: Inspecting Your Mini Cooper Key Fob
Familiarize yourself with your key fob. Notice the chrome ring and the seam where the two halves of the fob are joined. Also, locate the emergency mechanical key release – this will remain functional throughout the process.
In case of any issues during the battery replacement, you can always use the mechanical key to access and operate your vehicle.
Step 2: Removing the Chrome Ring
The first step is to carefully remove the chrome ring that surrounds the key fob. Many online tutorials show this being done effortlessly, but be warned – it can be fragile.
Use a small, flat prying tool or screwdriver to gently lift the ring. Work slowly around the circumference. Even with utmost care, there’s a chance it might break, so proceed with caution.
Step 3: Opening the Key Fob Casing
This is the most delicate part. The key fob casing is glued together and needs to be carefully separated along its seam. A sharp knife is crucial for this step.
Secure the key fob firmly and safely. A vise with soft jaws or a block of wood can help stabilize it. Carefully run the knife along the seam, applying gentle but firm pressure to cut through the adhesive. Work around the entire circumference until the two halves begin to separate.
Once you’ve cut through the glue, gently pry the two halves apart.
Step 4: Accessing the Circuit Board
With the casing open, the circuit board should be easily accessible. It usually isn’t fixed too tightly and can be lifted out.
Step 5: Desoldering the Old Battery
The battery is soldered onto the circuit board. Carefully desolder the old battery using a soldering iron.
If you’re new to soldering, plenty of online resources can guide you. Apply heat to the solder joints and use a desoldering braid or pump to remove the solder. Gently lift the battery once the solder is removed.
Step 6: Identifying and Ordering the Correct Replacement Battery
The battery you need is a Panasonic VL2020-1HFN rechargeable battery, specifically designed for BMW/Mini key fobs.
When ordering, pay close attention to the battery clips. They come in different orientations (e.g., 180 degrees, 90 degrees). Ensure you order one with the correct clip configuration to match your original battery. The original battery shown has clips at 180 degrees.
Step 7: Soldering the New Battery
Solder the new VL2020-1HFN battery onto the circuit board in the same orientation as the old one.
It’s a good time to inspect the circuit board. You’ll see micro-switches for the buttons. These can sometimes wear out and be replaced. Cleaning them with electro cleaner can sometimes improve their responsiveness. Also, note the induction coil on the back of the board, used for wireless charging.
Important Note on Static Electricity: While the original author mentions precautions against electrostatic discharge (ESD), modern key fobs are fairly robust. However, if you’re working in a very dry environment, grounding yourself can be a good practice when handling electronic components.
Compare the old and new batteries side-by-side to confirm correct polarity and clip alignment before soldering.
Caution: Double-check the battery polarity (+ and -) before soldering. And, as shown in the original repair, it’s surprisingly easy to solder the battery on the wrong side of the circuit board!
Ensure the battery sits at the correct height above the circuit board for proper fitment back into the casing. Take your time and redo the soldering if needed to get it right.
Step 8: Reassembling the Key Fob
Carefully place the circuit board back into one half of the key fob casing.
Pay attention to the mechanical key locking mechanism. Ensure it aligns correctly as it only has a small range of motion.
Test fit the two halves of the casing, ensuring the mechanical key works smoothly. Once satisfied, apply plastic glue or epoxy to the edges of one half of the casing and carefully join the two halves.
Clamp or use rubber bands to hold the casing firmly together while the glue dries completely (usually 24 hours).
Step 9: Refitting the Chrome Ring (Optional)
Refitting the chrome ring can be tricky, especially if it was damaged during removal.
If needed, use a Dremel or small files to carefully reshape the plastic casing for better alignment. This step requires patience and finesse.
Step 10: Testing Your Repaired Key Fob
After reassembly and glue drying, test your key fob. It should now function correctly, and the low battery warning should disappear.
Conclusion
Replacing the battery in a “sealed” 2011 Mini Cooper key fob is definitely achievable with DIY skills. While it requires careful work, especially opening the glued casing and soldering, the satisfaction of saving money and extending the life of your key fob is well worth the effort. By following these steps, you can confidently tackle this repair and keep your Mini Cooper key working perfectly.
