Step-by-Step Guide: How to Change a Battery in a Mercedes Key Fob

A functioning car key ensures seamless access to your Mercedes vehicle. Frequent use or low temperatures can deplete the battery, causing inconvenience. Replacing the battery in your LCD smart car key is a simple task you can do yourself. This guide will show you how to change a battery in a Mercedes key fob efficiently. Save money and avoid the hassle of visiting a dealership by following these straightforward steps.

How to Change a Battery in a Mercedes Key Fob: First Generation

Identifying the First Generation Key Fob

Visual Characteristics

First-generation key fobs have a rectangular shape. The key fob features three buttons: lock, unlock, and trunk release. The casing has a matte finish with a silver Mercedes logo.

Common Models

The first-generation key fobs are common in older Mercedes models. These include the C-Class (W202), E-Class (W210), and S-Class (W140).

Tools Needed

List of Tools

You will need a small flathead screwdriver and a new CR2025 battery. The flathead screwdriver helps open the key fob without damaging it.

Where to Purchase

Purchase these tools at any hardware store or online. Many automotive stores also carry CR2025 batteries.

Step-by-Step Instructions

Opening the Key Fob

1. Locate the small tab at the bottom of the key fob.

2. Pull the tab to release the emergency key.

3. Insert the flathead screwdriver into the slot where the emergency key was.

4. Gently twist the screwdriver to pry open the key fob.

Removing the Old Battery

1. Identify the battery compartment inside the key fob.

2. Use the flathead screwdriver to lift the old battery out of its compartment.

3. Dispose of the old battery properly. Batteries can harm the environment if not disposed of correctly.

Inserting the New Battery

1. Take the new CR2025 battery.

2. Place the new battery into the compartment with the positive (+) side facing up.

3. Ensure the battery sits firmly in place.

Reassembling the Key Fob

1. Align the two halves of the key fob casing.

2. Press the halves together until you hear a click.

3. Insert the emergency key back into its slot.

4. Test the key fob to ensure it works correctly.

How to Change a Battery in a Mercedes Key Fob: Second Generation

Identifying the Second Generation Key Fob

Visual Characteristics

Second-generation key fobs have a more streamlined design compared to the first generation. The casing features a glossy finish with a chrome Mercedes logo. The key fob includes three buttons: lock, unlock, and panic.

Common Models

Second-generation key fobs are common in mid-2000s Mercedes models. These include the C-Class (W203), E-Class (W211), and S-Class (W220).

Tools Needed

List of Tools

You will need a small flathead screwdriver and a new CR2025 battery. The flathead screwdriver helps open the key fob without causing damage.

Where to Purchase

Purchase these tools at any hardware store or online. Many automotive stores also carry CR2025 batteries.

Step-by-Step Instructions

Opening the Key Fob

1. Locate the small tab at the bottom of the key fob.

2. Pull the tab to release the emergency key.

3. Insert the flathead screwdriver into the slot where the emergency key was.

4. Gently twist the screwdriver to pry open the key fob.

Removing the Old Battery

1. Identify the battery compartment inside the key fob.

2. Use the flathead screwdriver to lift the old battery out of its compartment.

3. Dispose of the old battery properly. Batteries can harm the environment if not disposed of correctly.

Inserting the New Battery

1. Take the new CR2025 battery.

2. Place the new battery into the compartment with the positive (+) side facing up.

3. Ensure the battery sits firmly in place.

Reassembling the Key Fob

1. Align the two halves of the key fob casing.

2. Press the halves together until you hear a click.

3. Insert the emergency key back into its slot.

4. Test the key fob to ensure it works correctly.

How to Change a Battery in a Mercedes Key Fob: Third Generation

Identifying the Third Generation Key Fob

Visual Characteristics

Third-generation key fobs have a sleek, modern design. The casing features a glossy finish with a chrome Mercedes logo. The key fob includes four buttons: lock, unlock, trunk release, and panic.

Common Models

Third-generation key fobs are common in recent Mercedes models. These include the C-Class (W204), E-Class (W212), and S-Class (W221).

Tools Needed

List of Tools

You will need a small flathead screwdriver and a new CR2025 battery. The flathead screwdriver helps open the key fob without causing damage.

Where to Purchase

Purchase these tools at any hardware store or online. Many automotive stores also carry CR2025 batteries. High-quality batteries ensure longer life for your car key.

Step-by-Step Instructions

Opening the Key Fob

1. Locate the small tab at the bottom of the key fob.

2. Pull the tab to release the emergency key.

3. Insert the flathead screwdriver into the slot where the emergency key was.

4. Gently twist the screwdriver to pry open the key fob.

Removing the Old Battery

1. Identify the battery compartment inside the key fob.

2. Use the flathead screwdriver to lift the old battery out of its compartment.

3. Dispose of the old battery properly. Batteries can harm the environment if not disposed of correctly.

Inserting the New Battery

1. Take the new CR2025 battery.

2. Place the new battery into the compartment with the positive (+) side facing up.

3. Ensure the battery sits firmly in place.

Reassembling the Key Fob

1. Align the two halves of the key fob casing.

2. Press the halves together until you hear a click.

3. Insert the emergency key back into its slot.

4. Test the key fob to ensure it works correctly.

Changing the battery in a Mercedes key fob is simple and straightforward. You can perform this task yourself without any special skills. Attempting this DIY project saves money and provides convenience. A high-quality battery ensures longer life for your key fob, avoiding frequent replacements. Always dispose of old batteries properly to protect the environment. Give it a try and enjoy the benefits of a fully functional key fob.

See Also

Step-by-Step Guide for Replacing Your Car Key Fob

Guide on Replacing a Misplaced Car Key Fob

Replacing Your Car Key or Key Fob Made Easy

DIY Guide for Replacing Your Car Key or Key Fob

Switching to a Smart Car Key: Step-by-Step Battery Replacement