Is your Mini Cooper flashing a low key fob battery warning? As your trusted auto repair experts at keyfobx.com, we understand the frustration. If you’re like many Mini owners with the standard package, you might be facing a sealed key fob, seemingly designed to prevent DIY battery replacement. BMW/Mini often suggests professional replacement, which can be costly. But don’t worry, changing your mini key fob battery at home is achievable with the right guidance. This comprehensive guide will walk you through each step of a Mini Key Fob Battery Change, empowering you to tackle this task yourself and save money.
Many modern car key fobs, including those for Mini Coopers without the comfort access package, come with sealed units. Unlike older key fobs with easily replaceable batteries, these are designed without obvious access points. This design often leads owners to believe that battery replacement is impossible or requires professional service. However, as seasoned auto repair professionals, we know that with careful work and the correct approach, a mini key fob battery change is a manageable DIY project.
Before we dive into the process, let’s clarify something. You might wonder, like many, about the origin of the term “key fob.” Interestingly, “fob” historically referred to ornaments attached to watch chains dating back to the late 19th century. Its association with keys evolved, possibly from the German word “Fuppe” (pocket) or “foppen” (sneak-proof), eventually leading to the “key fob” we know today.
Now, back to your Mini key. If your Mini included the comfort package, your key fob would likely have a user-removable battery, as illustrated in the owner’s manual.
However, for those without this package, facing a sealed unit can be daunting. The prospect of a dealership key fob replacement cost can be significant. This is where our expertise at keyfobx.com comes in. We believe in empowering car owners with the knowledge to maintain their vehicles. Let’s explore how to perform a mini key fob battery change on these sealed units.
This guide is based on our hands-on experience and is intended to provide a detailed walkthrough. Remember to proceed with caution and patience. While we aim to be comprehensive, keyfobx.com is not liable for any damage incurred during your DIY attempt.
Tools Required for Your Mini Key Fob Battery Change
Before starting, gather these tools:
- Small, sharp knife or precision blade: Essential for carefully separating the key fob casing.
- Small flat-head screwdriver or plastic pry tool: Helpful for prying open the casing and circuit board.
- Soldering iron and solder: For desoldering the old battery and soldering in the new one.
- Desoldering braid or pump (optional but recommended): To remove excess solder.
- Replacement battery (Panasonic VL2020-1HFN): Ensure you get the correct type; we’ll discuss this in detail.
- Multimeter (optional but recommended): To check battery polarity and voltage.
- Plastic glue or epoxy: For reassembling the key fob casing.
- Clamps or rubber bands: To hold the casing together while the glue dries.
Step-by-Step Mini Key Fob Battery Replacement
Let’s get started with the battery replacement process.
Step 1: Examining Your Mini Key Fob
First, familiarize yourself with your Mini key fob. It will likely resemble this:
Notice the chrome ring and the absence of any screws or battery compartment. This confirms it’s a sealed unit. Also, remember that most Mini key fobs contain a mechanical key for emergency access if the battery completely dies.
Step 2: Carefully Opening the Key Fob Casing
This is the most delicate part. The goal is to separate the two halves of the key fob casing without causing significant damage. Many online videos demonstrate prying off the chrome ring first. However, be extremely cautious, as this ring is fragile.
As you can see, even with care, the chrome ring can break. Proceed slowly and gently. Next, focus on the seam around the side of the key fob. Using your sharp knife, carefully begin to cut along this seam.
A vice with soft padding can help secure the key fob while you cut, but ensure you don’t apply too much pressure. Work your knife around the entire circumference of the key fob, gradually deepening the cut. Patience is key here. Once you’ve cut deep enough, you should be able to gently pry the two halves apart.
Step 3: Accessing the Circuit Board and Battery
With the casing open, the internal circuit board should be accessible. In many cases, it might lift out easily.
Step 4: Desoldering the Old Battery
Now you’ll see the battery soldered to the circuit board.
Carefully use your soldering iron to desolder the battery terminals from the circuit board. If you have desoldering braid or a pump, use it to remove excess solder for a cleaner removal.
Step 5: Identifying and Ordering the Correct Replacement Battery
The battery is typically a rechargeable button cell. In this Mini key fob, it’s a Panasonic VL2020-1HFN rechargeable BMW-Mini battery.
Note the specific model number VL2020-1HFN. Search online using this number to find a replacement. Crucially, pay attention to the battery terminals (clips). As you can see, these terminals can vary in angle and size.
These key fobs use induction charging, meaning they charge wirelessly when inserted into the dashboard slot. This is why there are no external charging contacts.
When ordering your new battery, ensure the terminals match the old one in orientation and size to ensure proper soldering and connection to the circuit board. Double-check the polarity (+ and -) markings on both the old and new batteries.
Step 6: Soldering the New Battery
Once your new battery arrives, compare it to the old one.
Verify the polarity and terminal alignment. Carefully solder the new battery onto the circuit board in the correct orientation. It’s easy to make mistakes, even for experienced DIYers!
Ensure you solder the battery on the correct side of the board and at the correct height for proper reassembly. If you make a mistake, carefully desolder and resolder it correctly.
Step 7: Reassembling the Key Fob
Now it’s time to put everything back together.
Carefully align the circuit board and mechanical key mechanism within the casing. Ensure the mechanical key locking mechanism functions correctly.
Test the mechanical key function several times before gluing the casing halves together. Once satisfied, apply plastic glue or epoxy to the edges of the casing and carefully press the two halves together.
Use clamps or rubber bands to hold the casing firmly together while the glue dries completely, ideally for 24 hours.
Step 8: Refitting the Chrome Ring (Optional)
Refitting the chrome ring can be challenging, especially if it was damaged during removal.
You may need to carefully file or trim any rough edges on the plastic casing to ensure a snug fit for the ring. This might require patience and fine adjustments.
Step 9: Final Testing
Once reassembled and the glue is dry, test your key fob. The low battery warning should be gone, and your remote locking/unlocking should work perfectly.
Conclusion
Congratulations! You’ve successfully completed a mini key fob battery change on a sealed unit. This DIY project can save you a significant amount compared to dealership replacement costs. While it requires care and precision, following these steps from keyfobx.com will guide you through the process. Remember to source the correct replacement battery (Panasonic VL2020-1HFN) and take your time, especially when opening the casing and soldering.
For more expert auto repair guides and key fob solutions, visit keyfobx.com, your trusted resource for automotive knowledge and DIY assistance.
