Is your Mini Cooper key fob displaying a low battery warning? You’re not alone. Many Mini owners face this issue, and while dealerships might suggest a costly key fob replacement, changing the battery yourself is a surprisingly straightforward task. Especially if you have a sealed key fob, where manufacturers don’t officially support battery replacement. This guide will walk you through the process of replacing the battery in your non-comfort package Mini key fob, saving you money and hassle.
Tools and Materials You’ll Need
Before you begin, gather these essential tools and materials:
- New Battery: Panasonic VL2020-1HFN rechargeable battery (ensure the clips are compatible with your circuit board).
- Small Flathead Screwdriver or Pry Tool: For carefully opening the key fob.
- Sharp Knife or Precision Blade: To cut through the glued casing.
- Soldering Iron and Solder: For desoldering and resoldering the battery.
- Desoldering Pump or Wick (Optional): To help remove old solder.
- Multimeter (Optional but Recommended): To check battery polarity and connections.
- Plastic Glue or Epoxy: To reassemble the key fob casing.
- Clamps or Rubber Bands: To hold the casing together while the glue dries.
- Dremel or Files (Optional): For refining the chrome ring fit during reassembly.
- Electro Cleaner (Optional): To clean micro-switches.
Step-by-Step Guide to Replacing Your Mini Key Fob Battery
Follow these detailed steps to safely and effectively replace your Mini key fob battery:
Step 1: Removing the Chrome Ring
The first step is to carefully remove the chrome ring that surrounds the key fob. This ring is delicate and can break easily, as demonstrated in the original guide. Use a small flathead screwdriver or pry tool to gently work around the edges of the ring, applying steady, even pressure. Patience is key here.
Step 2: Opening the Key Fob Casing
This is arguably the trickiest part. Mini key fobs without the comfort package are sealed and glued shut. You’ll need a sharp knife or precision blade to carefully cut along the seam of the key fob casing. Work slowly and methodically around the entire circumference. Using a vice and some wood blocks, as shown in the original guide, can help stabilize the key fob and protect your hands.
Once you’ve cut deep enough along the seam, gently pry the two halves of the key fob apart.
Step 3: Accessing the Circuit Board and Battery
With the casing open, the circuit board should be easily accessible. In most cases, it will lift out without much resistance.
Locate the battery on the circuit board. It’s typically a small, button-shaped rechargeable battery, like the Panasonic VL2020-1HFN.
Step 4: Desoldering and Replacing the Battery
Carefully desolder the old battery from the circuit board. Note the polarity (+ and -) and the orientation of the battery before removal. A soldering iron and desoldering pump or wick will make this task easier.
Take your new Panasonic VL2020-1HFN battery and ensure it has the correct clips and orientation to match the original. Solder the new battery in place, making sure you have correct polarity and a secure connection. Double-check your soldering to ensure it’s clean and solid.
A common mistake to avoid is soldering the battery on the wrong side of the circuit board, as highlighted in the original guide. Always double check the correct placement before soldering!
Step 5: Reassembling the Key Fob
Carefully place the circuit board back into one half of the key fob casing. Before gluing the halves back together, test the mechanical key mechanism to ensure it operates smoothly.
Apply plastic glue or epoxy to the edges of the casing halves and carefully press them together. Use clamps or rubber bands to hold the casing firmly while the glue dries completely, ideally for 24 hours.
Once the glue is dry, refit the chrome ring. This might require some adjustments due to the slight imperfections from opening the sealed casing. Use a Dremel or files to carefully refine the fit if necessary.
Testing and Final Steps
After reassembly, test your Mini key fob to ensure it’s working correctly. The low battery warning should be gone, and your key fob should now lock and unlock your car remotely.
Congratulations! You’ve successfully changed the battery in your Mini key fob. This DIY approach not only saves you money compared to dealership replacement costs but also gives you the satisfaction of fixing it yourself. Remember to dispose of the old battery responsibly.
