Changing a key battery for a Mercedes is a simple task that can be completed in a few minutes. All you need is a new battery and a small screwdriver. However, if you’re not comfortable working on your car, it’s best to leave this job to a professional.
To begin, locate the battery compartment on the back of the key. It’s usually held in place by a small screw. Once you’ve found the battery compartment, use the screwdriver to carefully remove the screw. Then, lift the compartment open and replace the old battery with the new one. Make sure to match the positive and negative terminals correctly. Finally, close the battery compartment and tighten the screw.
If you’re having trouble changing the key battery, don’t hesitate to consult your Mercedes dealership. They’ll be able to assist you quickly and easily. In addition to the steps above, here are a few additional tips to keep in mind when changing a key battery for a Mercedes:
- Use a new battery. Do not use an old or used battery, as this could damage the key.
- Match the positive and negative terminals correctly. If the terminals are not matched correctly, the key will not work.
- Tighten the screw securely. If the screw is not tightened securely, the battery could come loose and fall out.
Unlock the Vehicle and Open the Key Fob
Preparation
Before proceeding, ensure that you have the following tools readily available:
- New CR2025 3V battery
- Small flathead screwdriver or key
- Optional: Gloves for added comfort
Step-by-Step Instructions
- Unlock the vehicle: Locate the keyhole on the driver’s side door handle. Insert the key and turn it clockwise to unlock the vehicle.
- Enter the vehicle: Open the door and enter the driver’s seat.
- Remove the key from the ignition: If the key is inserted into the ignition, remove it by turning it counterclockwise and pulling it out.
- Locate the key fob: In most Mercedes vehicles, the key fob is attached to the key ring. If not, check the interior pockets or cup holders for the fob.
- Release the key from the fob: Some key fobs have a small button that can be pressed to release the key. If your fob does not have a button, use a flathead screwdriver or key to gently pry open the seam between the key and the fob.
Additional Tips
- Safely store the key: While you’re replacing the battery, keep the key safely stored in a pocket or purse to avoid losing it.
- Protect the key fob: Handle the key fob with care to avoid damaging its delicate electronics.
- Clean the key fob: If the key fob appears dirty or has visible debris, use a soft cloth and a gentle cleaning solution to clean its surface.
- Regular battery replacement: To ensure optimal performance of your key fob, it’s recommended to replace the battery every year or two, or as needed.
Locate the Key Battery Compartment
Identifying the battery compartment is crucial for a successful key battery replacement. In Mercedes-Benz vehicles, it’s typically located in one of these three places:
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Inside the Key Fob: For key fobs that split into two parts, the battery compartment may be concealed within the smaller removable component. Check for a small button or lever that releases this section.
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Beneath the Keypad: Some Mercedes key fobs feature a keypad for inputting a security code. If your fob has this feature, the battery compartment might be nestled underneath the keypad. Gently pry open the keypad using a small flathead screwdriver or a plastic pry tool.
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Within the Key Compartment: In older Mercedes vehicles, the key compartment may have a separate battery compartment located within the main key housing. Insert the key into the ignition and turn it to the "Accessory" position. You may be able to access the battery compartment by prying open a small door or cover in the key housing.
Use a Small Flathead Screwdriver to Open the Compartment
The first step in changing the key battery for a Mercedes is to open the key compartment. This can be done by inserting a small flathead screwdriver into the notch on the side of the key and gently prying it open. Be careful not to use too much force, as you could damage the key.
Once the key compartment is open, you will see the battery. The battery is held in place by a small clip. To remove the battery, simply push down on the clip and slide the battery out.
When inserting the new battery, be sure to pay attention to the polarity. The positive terminal of the battery should be facing up. Once the new battery is in place, simply clip it back into place and close the key compartment.
Here are some additional tips for changing the key battery for a Mercedes:
| Tip | Description |
|---|---|
| Use a new battery. | Old batteries can leak and damage the key. |
| Be careful not to touch the battery terminals. | The oils from your skin can damage the battery. |
| If the key still does not work after changing the battery, there may be another issue. | You may need to take the key to a qualified technician for further diagnosis. |
Remove the Old Battery
To successfully replace the key battery, you will need to remove the old battery from the key fob. Here’s a detailed guide to help you with this step:
1. Locate the Battery Compartment
Identify the small compartment on the key fob that houses the battery. It is usually covered by a small plastic or metal flap. Locate the release button or latch that allows you to open the compartment.
2. Open the Battery Compartment
Carefully pry open the battery compartment using a small screwdriver or a flat-head object. Avoid using excessive force to prevent damaging the fob.
3. Remove the Old Battery
Once the compartment is open, you will see the old battery. Use tweezers or a small object to gently lift the battery out of its holder. Be cautious not to touch the battery terminals with your fingers, as it can discharge the battery faster.
4. Inspect the Battery and Contact Points
Before inserting the new battery, take a moment to inspect the battery terminals in the compartment. Ensure that they are clean and free of any corrosion or debris. If necessary, use a cotton swab with a small amount of rubbing alcohol to gently clean the contacts.
Cleaning the contact points ensures good electrical conductivity and prevents potential issues with the key fob functionality.
Secure the Battery Compartment
The battery compartment is located under the hood of your Mercedes-Benz. It is secured by a plastic cover that is held in place by two screws. To remove the cover, turn the screws counterclockwise and lift the cover off.
Once the cover is removed, you will see the battery. It is held in place by a metal bracket that is attached to the battery terminals. To remove the battery, first disconnect the negative terminal (the black wire) by loosening the nut that secures it to the terminal.
Then, disconnect the positive terminal (the red wire) by loosening the nut that secures it to the terminal. Once both terminals are disconnected, lift the battery out of the compartment.
Battery Removal Steps
| 1. | 2. | 3. |
|---|---|---|
| Turn screws counterclockwise. | Lift the cover off. | Disconnect negative terminal (black wire). |
| Disconnect positive terminal (red wire). | Lift battery out of the compartment. | |
| Inspect battery for damage. | Clean battery terminals if necessary. | Insert new battery into compartment. |
| Connect positive terminal (red wire). | Connect negative terminal (black wire). | Replace cover and tighten screws. |
To install the new battery, simply reverse the steps that you used to remove the old battery. Once the new battery is installed, connect the negative terminal first, followed by the positive terminal. Tighten the nuts that secure the terminals to the battery posts.
Test the Key Fob
Before you begin, test the key fob to ensure that the battery requires replacement. Here are the steps:
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Unlock the car using the key fob from a reasonable distance.
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Press any button on the fob.
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If the lights on the fob are dim or don’t illuminate, it’s likely that the battery needs to be replaced.
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If you have a spare key fob, try using it to unlock the car.
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If the spare fob works normally, the problem is most likely with the battery in the original fob.
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If neither fob works, the issue may be with the car’s receiver unit or the key fob system.
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Note that some Mercedes models have a battery status indicator on the key fob. If the indicator shows a low battery level, the battery should be replaced.
Remove the Screw
Locate the small screw at the back of the key fob. Use a Phillips head screwdriver to carefully remove the screw, being mindful not to strip the head.
Separate the Fob Halves
Once the screw is removed, gently pry open the two halves of the key fob. Use a small flathead screwdriver or a plastic pry tool to avoid damaging the delicate components inside.
Locate the Battery
Inside the key fob, you will see the battery, typically a small CR2025 or CR2032 button-cell battery. It is usually located in a dedicated battery compartment or held in place by a small clip.
Remove the Old Battery
Using a small flathead screwdriver or a plastic pry tool, carefully remove the old battery from its compartment. Be cautious not to touch the battery terminals with your fingers, as this can affect the battery’s performance.
Insert the New Battery
Take the new battery and insert it into the compartment with the positive (+) side facing up. Ensure that the battery is securely in place, making good contact with the terminals.
Close the Fob Halves
Once the new battery is in place, carefully align the two halves of the key fob and press them together until they snap into place. Make sure the fob is securely closed, and the buttons are functioning smoothly.
Replace the Screw
Locate the screw you removed earlier and gently screw it back into place at the back of the key fob. Tighten the screw securely, but avoid overtightening to prevent stripping the threads.
Test the Key Fob
Press the buttons on the key fob to ensure it is working properly. If the buttons are not responsive, double-check that the battery is correctly inserted and the fob is closed securely. If the issue persists, consult a locksmith or Mercedes-Benz dealership for further assistance.
Unfold the Key
Before beginning the actual battery change, unfold the key to reveal the internal components.
Remove the Emergency Key
Locate the small emergency key within the main key and gently pull it out. This is a small, notched key that can be used if the battery dies.
Identify the Release Button
On the back of the key, find the release button. This button is typically located in the center or towards the top of the key.
Press the Release Button
Using the emergency key or a small screwdriver, press and hold the release button for 2-3 seconds. This should cause the key shell to slide open.
Separate the Key Shell
Carefully separate the two halves of the key shell. One half will contain the electronics and battery, while the other half is the key head.
Locate the Battery
Inside the electronic half of the key shell, locate the small, round battery. It is usually held in place by a metal clip.
Replace the Battery
Using a small screwdriver or tweezers, carefully remove the old battery from the clip. Insert the new CR2025 battery into the clip, ensuring the positive (+) side is facing up.
Reassemble the Key
Fit the two halves of the key shell back together and press them firmly until they click into place. The key should now be functional with the new battery.
Dispose of the Old Battery Safely
Once you have removed the old battery, it is important to dispose of it properly. Car batteries contain lead and acid, which can be harmful to the environment if not disposed of properly. Here are some tips for disposing of your old battery safely:
- Check with your local recycling center. Many recycling centers accept car batteries for recycling.
- Take the battery to an auto parts store. Many auto parts stores offer battery recycling services.
- Dispose of the battery at a household hazardous waste collection event. These events are often held by local governments or environmental organizations.
Do not throw your old battery in the trash. It is illegal to dispose of car batteries in the trash in most places.
By following these tips, you can help to protect the environment and ensure that your old battery is disposed of properly.
| Battery Type | Approximate Weight | Approximate Dimensions (L x W x H) |
|---|---|---|
| CR2025 | 2 grams | 20 x 2.5 x 2.5 mm |
| CR2032 | 3 grams | 20 x 3.2 x 2.5 mm |
| CR1620 | 1.5 grams | 16 x 2 x 2 mm |
| CR1632 | 2 grams | 16 x 3.2 x 2 mm |
| LR44 | 0.5 grams | 11.6 x 5.4 x 5.4 mm |
How to Change the Key Battery for a Mercedes
Replacing the battery in your Mercedes key fob is a simple task you can do yourself. Here are the steps:
- Remove the key from the fob. Press the button on the side of the fob to release the key.
- Open the fob. There is a small latch on the back of the fob. Use a small screwdriver or your fingernail to pry open the latch.
- Locate the battery. The battery is a small, round coin-shaped battery. It is usually located in the center of the fob.
- Remove the old battery. Use a pair of tweezers to gently remove the old battery.
- Insert the new battery. Make sure the positive side of the battery is facing up.
- Close the fob. Snap the latch back into place.
- Test the key. Press the buttons on the fob to make sure they are working.
People Also Ask
How often should I replace the battery in my Mercedes key fob?
You should replace the battery in your Mercedes key fob every two to three years.
What type of battery does my Mercedes key fob use?
Your Mercedes key fob uses a CR2025 battery.
Can I change the battery in my Mercedes key fob myself?
Yes, you can change the battery in your Mercedes key fob yourself. It is a simple task that takes only a few minutes.
How do I know if the battery in my Mercedes key fob is dead?
There are a few signs that the battery in your Mercedes key fob is dead. The buttons may not work, the fob may not unlock the car, or the fob may not start the car.
