Is your Mini Cooper displaying a low key battery warning? Don’t rush to the dealership just yet! If you’re facing the dreaded “low key fob battery” message on your Mini Cooper’s dashboard, you might think a costly trip to the dealership is inevitable. Especially if you, like many Mini owners, discover you have the sealed key fob – seemingly designed to prevent DIY battery replacements. But fear not! Replacing the battery in your Mini Car Key Fob is a surprisingly achievable DIY project that can save you a significant amount of money and give you a satisfying sense of accomplishment.
This guide will walk you through the process of replacing the rechargeable battery in a sealed Mini car key fob. While BMW/Mini might prefer you buy a brand new, expensive replacement key, we’ll show you how to tackle this repair yourself with some basic tools and a little patience. Let’s get started and bring your mini car key fob back to life!
Understanding Your Mini Key Fob: Comfort Access vs. Standard
Mini Coopers, depending on their specification, come with different types of key fobs. According to the original Mini owner’s manual, key fobs are categorized based on whether your Mini has the “comfort package” or not. The comfort package key fob is designed for easy battery replacement, featuring a removable battery compartment. This is the user-friendly option.
However, if your Mini, like the one featured in this guide, doesn’t have the comfort package, you’re likely dealing with a sealed mini car key fob. These fobs are designed without an obvious way to access the battery, leading many owners to believe battery replacement is impossible or requires professional (and expensive) service. BMW/Mini designed these sealed fobs with induction charging, intending for the battery to be charged when the key fob is placed in the designated slot on the dashboard. But rechargeable batteries do have a lifespan, and eventually, they will need replacing.
Tools and Materials Needed for Mini Car Key Fob Battery Replacement
Before you begin, gather these tools and materials:
- Replacement Battery: Identify the correct battery for your mini car key fob. In this guide, we’re using a Panasonic VL2020-1HFN rechargeable battery. Make sure to verify the correct type for your specific fob, as variations exist. Pay close attention to the orientation and type of connector clips.
- Small, Sharp Knife: A precision knife or craft knife with a sharp blade is essential for carefully opening the sealed key fob.
- Small Screwdriver or Pry Tool: For gently prying open the key fob and lifting components.
- Soldering Iron and Solder: For desoldering the old battery and soldering in the new one. If you are not comfortable with soldering, consider seeking help from someone experienced.
- Electro Cleaner (Optional): For cleaning the micro-switches inside the key fob.
- Plastic Glue: To re-seal the key fob casing.
- Clamps: To hold the key fob casing together while the glue dries.
- Dremel or Files (Optional): May be needed to refine the edges of the key fob casing after opening.
- Multimeter (Recommended): To check battery polarity and ensure correct connection.
- Workstation with Vice and Wood Block (Optional but Recommended): To securely and safely hold the key fob while working on it.
Step-by-Step Guide to Replacing Your Mini Car Key Fob Battery
Now, let’s get into the step-by-step process of replacing your mini car key fob battery. Remember to work carefully and patiently to avoid damaging the delicate components.
Step 1: Removing the Chrome Ring
The first step is to remove the chrome ring that surrounds the key fob. This ring is clipped on and needs to be carefully pried off. Many online videos show this being done effortlessly, but be warned: it can be fragile.
Using a small screwdriver or pry tool, gently work your way around the ring, applying even pressure to avoid breaking it. Even with caution, as seen in the original attempt, the ring can still break. Proceed slowly and accept that this part might be delicate.
Step 2: Opening the Sealed Key Fob Casing
This is the trickiest part. The mini car key fob casing is glued shut and needs to be carefully cut open along the seam.
Secure the key fob in a vice or clamp, using a soft material like wood or rags to protect the surface. Using your sharp knife, carefully cut along the seam of the key fob. Apply steady pressure and go around the entire circumference multiple times, gradually deepening the cut. Take your time and be extremely cautious to avoid cutting yourself.
Once you’ve cut deep enough, you should be able to gently pry the two halves of the key fob casing apart.
Step 3: Accessing the Circuit Board and Battery
With the casing open, the internal circuit board should be easily accessible. In most cases, it will simply lift out.
Locate the battery on the circuit board. It’s usually a small, button-cell rechargeable battery with soldered clips.
Step 4: Desoldering and Replacing the Battery
Carefully desolder the old battery from the circuit board. Take note of the battery’s orientation (+ and -) and the position of the connector clips before removing it. A close-up of the battery shows it is a Panasonic VL2020-1HFN.
Solder the new Panasonic VL2020-1HFN battery (or the correct replacement for your fob) into place, ensuring correct polarity and clip orientation. Double-check that the positive (+) and negative (-) terminals are correctly aligned. As demonstrated in the original attempt, it’s easy to solder the battery on the wrong side, so pay close attention!
If desired, you can use electro cleaner to spray and clean the micro-switches on the circuit board while it’s accessible. This can improve the button responsiveness of your key fob.
Step 5: Reassembling the Mini Car Key Fob
Carefully place the circuit board back into the key fob casing. Test the mechanical key mechanism to ensure it’s working correctly before sealing the casing.
Apply plastic glue to the edges of the casing and carefully press the two halves together. Use clamps to hold the casing firmly together while the glue dries completely, ideally for 24 hours.
Once the glue is dry, you can attempt to refit the chrome ring. This might require some adjustment with a Dremel or files to ensure a proper fit, especially if the casing edges are not perfectly aligned after being cut open.
Tips for Success and Troubleshooting
- Patience is key: Take your time and work carefully throughout the process. Rushing can lead to mistakes or damage.
- Sharp knife is crucial: A sharp knife makes opening the sealed casing much easier and cleaner.
- Double-check battery polarity: Ensure the new battery is soldered with the correct polarity to avoid damaging the circuit board.
- Test before gluing: Before sealing the casing, test the key fob to ensure it’s working correctly.
- Consider professional help for soldering: If you’re uncomfortable with soldering, seek assistance from someone with electronics repair experience.
- Battery Clip Variations: Be aware that even the same battery model can have different clip configurations. Ensure the replacement battery’s clips match your original battery.
Conclusion: DIY Mini Car Key Fob Battery Replacement is Achievable
Replacing the battery in your sealed mini car key fob might seem daunting, but as this guide demonstrates, it’s a manageable DIY task. By following these steps and taking your time, you can successfully replace your mini car key fob battery, save money on dealership costs, and gain a valuable DIY skill. Say goodbye to low key battery warnings and enjoy the satisfaction of fixing it yourself!
