Is your 2012 BMW key fob starting to feel unresponsive, especially when the temperature drops? Many BMW owners, particularly those in colder climates, experience issues with their key fobs not working correctly in the cold. You might find yourself struggling to lock or unlock your car remotely, or even notice that your personalized vehicle settings, like radio presets and seat positions, are not being saved when starting your BMW. Often, the culprit is a weak or dead battery in your BMW key fob. Replacing the battery yourself is a straightforward process that can save you time and money compared to dealership service. This guide will walk you through replacing the battery in your 2012 BMW key fob, step-by-step.
Understanding When Your BMW Key Fob Battery Needs Replacing
Several signs indicate that your 2012 Bmw Key Fob Battery is nearing the end of its life and needs replacement. Keep an eye out for these common symptoms:
- Reduced Operating Range: You need to be much closer to your BMW for the key fob to lock or unlock the doors.
- Intermittent Button Response: You have to press the buttons on your key fob multiple times before your BMW responds.
- Loss of Personalized Settings: Your BMW may not remember your preferred radio stations, seat settings, or mirror positions after starting the car. This is particularly noticeable in colder weather.
- Cold Weather Sensitivity: The key fob works fine in warmer temperatures but becomes unreliable or stops working altogether when it’s cold.
These issues often stem from the degradation of the lithium-ion battery inside your BMW key fob over time. Like all batteries, these have a limited lifespan and are affected by usage patterns and environmental factors such as extreme temperatures. For 2012 BMW models and similar years, battery replacement is a common maintenance task as the original battery approaches its expected service life.
What You’ll Need: Tools and Battery
Before you begin the battery replacement, gather the necessary tools and the correct replacement battery. For a 2012 BMW key fob, you will typically need a VL2020 lithium-ion rechargeable battery. It’s crucial to purchase the correct battery type to ensure proper function and avoid damaging your key fob. You can find these batteries at online retailers like eBay or specialized battery stores.
Here’s what you’ll need:
- Replacement Battery: VL2020 Lithium-ion Battery (ensure correct terminal orientation – approximately 90-degree offset). You can find a suitable battery here: https://www.ebay.com/itm/NEW-MINI-BMW-1-3-5-X1-X3-X5-X6-Z4-E38-E39-E46-M5-KEY-FOB-LI-ION-VL2020-BATTERY/322831172386
- Sharp X-Acto Knife: For carefully cutting open the glued key fob casing.
- Non-metallic Pry Tool: A credit card or plastic pry tool works well to gently lift the battery without short-circuiting anything.
- Soldering Iron and Solder: To desolder the old battery and solder in the new one.
Step-by-Step Guide to Replacing Your 2012 BMW Key Fob Battery
Follow these steps to replace your 2012 BMW key fob battery. Work in a well-lit area and take your time to avoid damaging the key fob components.
Step 1: Opening the Key Fob
The BMW key fob is sealed with glue and needs to be carefully cut open. Using a sharp X-Acto knife, gently score along the seam of the key fob casing. Work slowly and patiently, making multiple shallow passes rather than trying to cut through in one go. Be extremely careful not to cut too deep, as you could damage the internal circuit board (PCB). Go around the entire perimeter of the fob until you can gently pry the two halves apart.
Step 2: Desoldering the Old Battery
Once the key fob is open, you’ll see the PCB with the battery soldered onto it. To remove the old battery, you’ll need to desolder it. Take your non-metallic pry tool (like a credit card) and gently wedge it under the edge of the battery to apply a slight upward tension. Focus on the corner terminal of the battery first. Apply heat to the solder joint of the corner terminal with your soldering iron until the solder melts. As the solder melts, the tension from your pry tool should help lift the terminal free. Repeat this process for the other terminal. Starting with the corner terminal is recommended because the middle terminal often has a longer lead and is harder to access initially.
Step 3: Soldering the New Battery
Now, place the new VL2020 battery into the battery holes on the PCB, ensuring correct polarity and orientation. Hold the PCB by its edges and gently press the battery down into place. Apply heat to the solder pad for the middle terminal on the PCB and feed in a small amount of solder to create a secure joint. Repeat this for the corner terminal. The battery terminals should push through the existing solder and seat properly onto the PCB. Ensure that the solder joints are clean and solid.
Step 4: Testing and Reassembly
Before permanently closing the key fob, it’s crucial to test if the new battery is working correctly. Dry fit the PCB back into the key fob housing and test all the buttons – lock, unlock, trunk, and panic. If everything works as expected, congratulations! You’ve successfully replaced your 2012 BMW key fob battery.
For reassembly, you have a couple of options. You can purchase a new replacement housing for your BMW key fob if you want a pristine look. Alternatively, you can simply glue the original housing back together. If you choose to glue it, use a gel-type cyanoacrylate glue sparingly. Apply a thin bead of glue along the seam and carefully press the two halves of the key fob together. Gel glue is recommended because it is less likely to run and seep into unwanted areas. Avoid using excessive glue, which could make it difficult to open the fob again in the future, and be careful not to glue the PCB to the housing itself.
Important Tips and Cautions
- Work Carefully: Take your time and be patient throughout the process, especially when opening the key fob and soldering.
- Sharp Knife Safety: Be extremely cautious when using the X-Acto knife to avoid injury.
- Avoid Deep Cuts: When opening the fob, make shallow cuts to prevent damage to the internal PCB.
- Correct Battery Polarity: Ensure you install the new battery with the correct polarity, matching the orientation of the old battery.
- Test Before Gluing: Always test the key fob functionality before gluing the housing back together.
- Soldering Safety: If you are not experienced with soldering, take necessary safety precautions and consider watching some soldering tutorials beforehand.
By following these steps, you can confidently replace your 2012 BMW key fob battery and restore its functionality, saving yourself a trip to the dealership and the associated costs.
