Replacing the battery in a Mercedes key fob is a simple task that can be done in a few minutes. However, if you’re not comfortable working with small electronics, you can always take your key fob to a locksmith or dealership and have them do it for you. Before you start, you’ll need to gather a few tools. You’ll need a small Phillips head screwdriver, a new CR2025 battery, and a soft cloth.
To start, use the screwdriver to remove the screws that hold the key fob together. Be careful not to lose the screws! Once the screws are removed, you can carefully pry the key fob open. You’ll see the battery inside. Use the soft cloth to carefully remove the battery. Be careful not to touch the metal contacts on the battery, as this can damage the key fob. Once the old battery is removed, you can insert the new battery. Make sure the positive (+) side of the battery is facing up. Once the new battery is in place, you can close the key fob and screw it back together.
Once the key fob is back together, test it out to make sure it’s working properly. If the key fob is not working, check to make sure that the battery is installed correctly. If the key fob still isn’t working, you may need to take it to a locksmith or dealership to have it repaired.
Identifying the Key Fob Battery Type
Knowing the battery type of your Mercedes key fob is crucial before attempting a replacement. Here’s a detailed guide to help you identify the battery:
- Step 1: Access the Key Fob Battery Compartment
Locate the small release button or lever on the side or bottom of the key fob. Press or slide it to detach the front or back cover, revealing the battery compartment.
- Step 2: Examine the Battery
Once you open the compartment, you’ll see the battery nestled inside. Note the size, shape, and any markings on the battery’s surface. Common battery types for Mercedes key fobs include CR2025, CR2032, CR2430, and CR2450.
- Step 3: Determine Battery Type Using Table
Refer to the table below to match the battery’s physical characteristics to its corresponding type:
| Battery Size (Diameter x Thickness) | Battery Type |
|---|---|
| 20mm x 2.5mm | CR2025 |
| 23mm x 2.5mm | CR2032 |
| 24mm x 3mm | CR2430 |
| 24mm x 5mm | CR2450 |
- Step 4: Additional Information on Battery Markings
Some batteries may have additional markings indicating their voltage and chemistry. For example, "3V" indicates a 3-volt battery, while "CR" stands for "lithium manganese dioxide." This information can provide further confirmation of the battery type.
Preparing the Key Fob for Disassembly
Gathering the Necessary Tools
Before beginning the disassembly process, it is crucial to gather the necessary tools and materials. You will require a small flat-head screwdriver or a key fob battery replacement tool to pry open the casing. You will also need a new CR2025 or CR2032 coin-cell battery (depending on your key fob model). To avoid any potential damage, ensure you have a clean and well-lit workspace.
Locating the Battery Release Mechanism
Once you have the necessary tools, locate the battery release mechanism on your key fob. The placement of this mechanism varies depending on the Mercedes-Benz model. Refer to your owner’s manual or online resources for specific instructions on locating the battery release mechanism for your particular key fob.
Carefully Releasing the Battery
Using the flat-head screwdriver or key fob battery replacement tool, gently pry open the battery release mechanism. This action should release the pressure holding the battery in place. Remove the old battery by carefully lifting it out of its compartment. Avoid touching the new battery with your bare hands, as this can transfer oils or dirt that could affect its performance.
Opening the Key Fob Casing
Replacing the battery in a Mercedes key fob is a relatively straightforward process that can be completed in a matter of minutes. The first step is to open the key fob casing. This can be done by carefully prying open the two halves of the casing using a small flathead screwdriver.
Once the casing is open, you will see the battery compartment. The battery is typically held in place by a small plastic clip. To remove the battery, simply use the tip of the screwdriver to gently pry the clip open.
Once the battery is removed, you can replace it with a new one. The new battery should be the same type and size as the old battery. To install the new battery, simply insert it into the battery compartment and make sure that the positive and negative terminals are aligned correctly.
Once the new battery is installed, you can close the key fob casing. To do this, simply snap the two halves of the casing back together. You may need to apply a little pressure to get the casing to close all the way.
Removing the Old Battery
1. Locate the battery compartment: It’s usually found on the back or bottom of the key fob and is held in place by a small screw or clip.
2. Remove the screw or clip: Use a small screwdriver or a paperclip to gently pry open the battery compartment.
3. Take out the old battery: Use your fingers or a pair of tweezers to carefully remove the old battery from the compartment.
4. Check the type of battery: Before inserting a new battery, check the shape and size of the old one to ensure you get the correct replacement.
5. Dispose of the old battery properly: Do not throw away the old battery with regular household trash. Instead, dispose of it at a designated recycling facility or battery disposal point to prevent environmental contamination.
| Common Battery Types Found in Mercedes Key Fobs | Shape/Size |
| CR2025 | Round, 20mm diameter, 2.5mm thickness |
| CR2032 | Round, 20mm diameter, 3.2mm thickness |
| CR1632 | Round, 16mm diameter, 3.2mm thickness |
Replacing the Battery in a Mercedes Key Fob
Inserting the New Battery
-
Gather Your Materials: You will need a new CR2025 or CR2032 watch battery and a small flathead screwdriver or key.
-
Pry Open the Fob: Insert the flathead screwdriver or key into the small notch on the side of the key fob. Gently pry the two halves of the fob apart.
-
Remove the Old Battery: Use your fingers or a pair of tweezers to carefully remove the old battery from the compartment.
-
Insert the New Battery: Align the positive (+) side of the new battery with the positive terminal in the compartment. Gently press down on the battery until it snaps into place.
-
Secure the Cover: Place the two halves of the key fob back together and align them properly. Press the two halves firmly together until they click into place.
-
Testing the Battery: Press the unlock button on the key fob to test if the new battery is working. If the key fob does not respond, check if the battery is inserted correctly and try again.
Closing the Key Fob Casing
Once the new battery is inserted, it’s time to reassemble the key fob casing. Follow these steps to close it securely:
-
Align the two halves of the casing, making sure the buttons are facing outwards.
-
Apply gentle pressure to snap the two halves together. You should hear or feel a click when they fully engage.
-
Insert the metal key (if applicable) back into its slot within the casing. Make sure it’s fully inserted and seated correctly.
-
If there is a screw that holds the casing together, use a small screwdriver to tighten it securely.
-
Gently tap the key fob on a flat surface to ensure it’s fully closed and all buttons are functioning properly.
-
Wipe down the key fob with a clean cloth to remove any dirt or fingerprints.
-
Test the key fob by pressing buttons and ensuring they respond as expected. If everything is working correctly, your battery replacement is complete.
Testing the Key Fob’s Functionality
Before replacing the battery, it’s important to confirm that the problem lies with the fob itself. Here’s how to test its functionality:
1. Check for physical damage: Inspect the fob for any cracks, dents, or loose buttons.
2. Clean the fob: Use a clean cloth or compressed air to remove any dirt or debris from the fob’s exterior and buttons.
3. Test the buttons: Press each button on the fob several times to see if they respond. If any buttons feel mushy or unresponsive, the battery may need replacement.
4. Test the LED light: If your fob has an LED indicator, press a button and observe if the light flashes. A weak or non-functioning light may indicate a low battery.
5. Try spare keys: If you have a spare key fob, try using that to unlock and start the vehicle. If the spare fob works, the issue likely lies with the primary fob’s battery.
6. Check for interference: Sometimes, electronic interference from other devices can disrupt the fob’s signal. Try moving away from nearby appliances or electronic devices and retesting the fob.
7. Reset the fob: Refer to your vehicle’s owner’s manual for specific instructions on how to reset the key fob. This may resolve any temporary software glitches that could affect the fob’s functionality.
8. Additional troubleshooting tips:
| Symptom | Possible Cause | Solution |
|---|---|---|
| Fob works intermittently | Battery is weak or degrading | Replace battery |
| Fob does not unlock from a distance | Antenna issues | Consult a mechanic or dealership |
| Fob works only when placed against the ignition | Battery is extremely low | Replace battery immediately |
| Fob triggers the alarm randomly | Buttons are sticking or jammed | Clean or replace the fob |
Troubleshooting Common Problems
If you’re having trouble replacing the battery in your Mercedes key fob, here are some common problems and their solutions:
1. The key fob isn’t working after replacing the battery. Make sure the battery is installed correctly and that the terminals are clean. If the key fob still doesn’t work, try replacing the battery again.
2. The key fob is working, but the range is very short. This could be a sign that the battery is low. Replace the battery with a new one.
3. The key fob is working, but the buttons are sticky or hard to press. This could be a sign that the key fob is dirty. Clean the key fob with a soft cloth and mild soap.
4. The key fob is working, but the LED light is not flashing. This could be a sign that the LED is burned out. Replace the key fob with a new one.
5. The key fob is working, but the car won’t start. This could be a sign that the key fob is not programmed to the car. Have the key fob programmed by a locksmith or dealer.
6. The key fob is working, but the car alarm is going off. This could be a sign that the key fob is not programmed to the car. Have the key fob programmed by a locksmith or dealer.
7. The key fob is not working, and the car won’t start. This could be a sign that the key fob or the car’s ignition system is malfunctioning. Have the key fob and car checked by a locksmith or dealer.
8. The key fob is working, but the doors won’t unlock. This could be a sign that the car’s door lock actuators are malfunctioning. Have the door lock actuators checked by a locksmith or dealer.
9. The key fob is working, but the trunk won’t open. This could be a sign that the car’s trunk release solenoid is malfunctioning. Have the trunk release solenoid checked by a locksmith or dealer.
How to Replace the Battery in a Mercedes Key Fob
Step 1: Gather Your Materials
You will need a new CR2025 battery and a small Phillips-head screwdriver.
Step 2: Remove the Key Blade
Flip open the key fob and locate the small button on the back. Press the button and slide the key blade out.
Step 3: Unscrew the Screws
Use the Phillips-head screwdriver to remove the two screws that hold the back cover in place.
Step 4: Remove the Back Cover
Gently pry the back cover off with your fingers.
Step 5: Remove the Old Battery
Use your fingers or a small screwdriver to remove the old battery from its housing.
Step 6: Insert the New Battery
Insert the new CR2025 battery into the housing with the positive side facing up.
Step 7: Replace the Back Cover
Place the back cover back on the key fob and press down to secure it.
Step 8: Replace the Screws
Use the Phillips-head screwdriver to replace the two screws that hold the back cover in place.
Step 9: Slide the Key Blade Back In
Slide the key blade back into the key fob until it clicks into place.
Step 10: Test the Key Fob
Press the buttons on the key fob to ensure that it is working correctly. If it is not working, repeat the steps and ensure that the battery is inserted correctly and that the screws are tightened securely.
Maintenance Tips for Extending Battery Life
Here are a few tips to help extend the battery life of your Mercedes key fob:
| Tip | Description |
|---|---|
| Avoid dropping your key fob | |
| Don’t leave your key fob in extreme temperatures | |
| Use your key fob only when necessary |
How to Replace the Battery in a Mercedes Key Fob
Here’s a step-by-step guide on how to replace the battery in your Mercedes key fob:
- Press the small button on the back of the key fob to release the emergency key.
- Use the emergency key to unlock the key fob.
- Remove the battery cover by sliding it off the top of the key fob.
- Replace the old battery with a new one. Make sure the positive (+) side of the battery is facing up.
- Replace the battery cover and slide it back into place.
- Test the key fob to make sure it’s working correctly.
People Also Ask
What type of battery does a Mercedes key fob use?
Mercedes key fobs typically use a CR2025 3-volt lithium battery.
How long does a Mercedes key fob battery last?
A Mercedes key fob battery typically lasts for about 2-3 years.
Can I replace the battery in a Mercedes key fob myself?
Yes, you can replace the battery in a Mercedes key fob yourself. It’s a quick and easy process that can be done in a few minutes.
How do I know if my Mercedes key fob battery is low?
There are a few signs that your Mercedes key fob battery may be low. These include:
- The key fob buttons don’t work as well as they used to.
- The key fob’s range is reduced.
- The key fob’s LED light blinks or is dim.
