Experiencing issues with your 2010 BMW 328i key fob, especially in cold weather? A common culprit is a failing key fob battery. Symptoms like reduced range or inconsistent locking/unlocking, and even loss of personalized car settings, can often be traced back to a weak battery. Fortunately, replacing the battery in your BMW 328i key fob is a straightforward DIY task that can save you a trip to the dealership. This guide will walk you through each step to replace your 2010 Bmw 328i Key Fob Battery and restore your key fob to optimal working condition.
What You’ll Need
Before you begin, gather these essential items:
- Replacement Battery: You’ll need a VL2020 lithium-ion rechargeable battery. Ensure you purchase the correct battery with the terminals oriented at approximately a 90-degree offset, as shown in the example here.
- Sharp X-Acto Knife or Precision Blade: For carefully opening the glued key fob casing.
- Non-Metallic Pry Tool: A credit card or plastic pry tool will work to gently lift the battery without damaging the circuit board.
- Soldering Iron and Solder: To desolder the old battery and solder in the new one.
- Safety Glasses: Protect your eyes during soldering.
- Cyanoacrylate Glue (Gel type recommended): To re-seal the key fob case after the battery replacement. (Alternatively, you can purchase a new key fob housing).
Step-by-Step Guide to Replacing Your BMW 328i Key Fob Battery
Follow these steps carefully to replace your 2010 BMW 328i key fob battery:
Step 1: Purchase the Correct Replacement Battery
It’s crucial to get the right battery. For a 2010 BMW 328i key fob, you’ll need a VL2020 rechargeable lithium-ion battery. Double-check the terminal orientation before purchasing to ensure it matches your old battery. The terminals are offset at roughly 90 degrees.
Step 2: Carefully Open the Key Fob Casing
The BMW key fob is sealed with glue and requires careful opening. Using a sharp X-Acto knife, gently score along the seam of the key fob casing. Work slowly and patiently, avoiding cutting too deep to prevent damage to the internal circuit board (PCB). Go around the entire perimeter of the fob to separate the top and bottom halves.
Step 3: Desoldering the Old Battery
Once the fob is open, you’ll see the PCB with the battery. Use a non-metallic pry tool, like a credit card, to gently apply a small amount of upward pressure to the battery. Focus on the corner terminal first. Apply heat with your soldering iron to the corner terminal solder joint to desolder it. The corner terminal is easier to access and desolder first, allowing better access to the middle terminal later.
Step 4: Soldering the New Battery
Place the new VL2020 battery into the designated holes on the PCB. Hold the PCB by its edges and gently press the battery down into place. Apply heat to the middle terminal solder pad on the PCB, allowing the solder to flow and secure the battery terminal. Repeat this process for the corner terminal, ensuring both terminals are firmly soldered to the PCB.
Step 5: Test and Reassemble
Before permanently sealing the key fob, dry-fit the PCB back into the housing and test the key fob functions (locking, unlocking, starting the car). If everything works correctly, proceed to the next step. If not, double-check your soldering and battery orientation.
Step 6: Closing the Key Fob
You have two options for closing the key fob: purchase a new replacement housing for a fresh look, or carefully glue the original housing back together. If gluing, use a gel-type cyanoacrylate glue sparingly to avoid it running and potentially gluing the PCB to the housing. Apply a small amount along the seam and press the two halves of the casing together until the glue sets.
Conclusion
Congratulations! You’ve successfully replaced the 2010 BMW 328i key fob battery. By following these steps, you can resolve common key fob issues related to battery failure and save money on dealership service costs. Enjoy the restored functionality of your BMW key fob.
