What is a CMOS Battery (CR2302)? Accurate Uses and Replace Process

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When we are using Computer, then various types of equipment built-ed in it. What is a CMOS Battery is one of the part of Computer system. It’s Used in every system like PC/Laptop/Desktop/Servers etc. CMOS Battery is one the very important part of our PC which was built in Motherboard which operate all Power and Input , output system.

What is a CMOS Battery
What is CMOS Battery

In this following article we are providing you full knowledge about CMOS Battery (CR2302) , it’s uses and replacement process for the same from the motherboard.

What is a CMOS Battery?

A CMOS (Complementary Metal-Oxide-Semiconductor) battery, also known as a motherboard battery, is a small, round-shaped battery found on the computer’s motherboard. It provides power to the complementary metal-oxide-semiconductor (CMOS) chip, which is responsible for storing the system’s BIOS (Basic Input/Output System) settings.

The CMOS battery ensures that important information, such as the date and time, hardware settings, and BIOS configurations, are retained even when the computer is powered off. It maintains this information by supplying a constant low-level electrical charge to the CMOS chip, which uses very little power.

CMOS Battery
CMOS Battery

When the computer is turned on, the BIOS reads the information stored in the CMOS chip to initialize the hardware and configure the system accordingly. If the CMOS battery is dead or removed, the BIOS will lose its settings and the computer may experience issues such as incorrect date and time, error messages during boot, or inability to recognize hardware components.

CMOS batteries are typically small, coin-shaped batteries, often CR2032 lithium batteries. They are easily replaceable and can be found on the motherboard, usually in a socket or holder. To replace a CMOS battery, you would typically power down the computer, locate the battery on the motherboard, carefully remove the old battery, and insert a new one with the correct polarity.

Uses of CMOS Battery(CR2302) in Computer World

The CMOS battery in the computer world serves several important purposes. Here are we are providing some main uses are:

Retaining BIOS Settings: The CMOS battery ensures that the computer's BIOS settings are retained even when the power is turned off. This includes settings related to hardware configuration, boot order, system time and date, and other low-level settings. Without the CMOS battery, the BIOS would reset to default values every time the computer is powered on.

Real-Time Clock (RTC): The CMOS battery powers the Real-time clock (RTC) in the computer. The RTC keeps track of the current time and date, even when the computer is shut down. This information is used by the operating system and various applications, such as scheduling tasks, file time-stamping, and event logging.

Power-On Self Test (POST): When the computer is powered on, the BIOS performs a Power-On Self Test (POST) to check the hardware components and ensure they are functioning correctly. The CMOS battery provides power to the BIOS during this initialization process, allowing it to access the stored configuration data and perform the necessary checks.

BIOS Firmware Updates: In some cases, updating the BIOS firmware of a computer may require a stable power source. The CMOS battery ensures that the BIOS update process is not interrupted due to power loss, preventing potential issues or bricking the motherboard.

Security Features: Some security features, such as BIOS passwords or encryption keys stored in the BIOS, rely on the CMOS battery. Without power from the CMOS battery, these security measures would be reset, preventing unauthorized access to the system or encrypted data.

Overclocking Stability: Overclocking refers to running the computer's components at higher speeds than their default settings to achieve better performance. The CMOS battery helps maintain stability in overclocked systems by retaining the BIOS settings required for optimal performance.

Overall, the Complementary Metal-Oxide-Semiconductor battery plays a crucial role in preserving essential system settings, ensuring proper initialization, and maintaining timekeeping functions in computers.

How to Replace CMOS Battery?

For replace the CMOS battery in a computer, follow these general steps:

Power off the computer: Shut down the computer and unplug it from the power source to ensure safety and prevent electrical damage.

Locate the CMOS battery: Open the computer case and locate the BIOS battery on the motherboard. It is usually a small, round-shaped battery, often a CR2032 lithium battery, placed in a socket or holder. Consult the motherboard manual if you’re having trouble finding it.

Replacement of CMOS Battery
Replacement of CMOS Battery

Prepare for replacement: Take note of the battery’s orientation and carefully remove it from its socket or holder. It may be held in place with a clip or latch that you need to gently release. If there is any dust or debris around the battery or socket, you can use compressed air or a soft brush to clean it.

Get a new battery: Purchase a replacement CMOS battery of the same type and size. The most common one is the CR2032 battery, but it’s essential to confirm the compatibility with your motherboard model.

Insert the new battery: Take the new CMOS battery and ensure its polarity matches the old one. The positive (+) side of the battery should face up. Carefully place the battery into the socket or holder, aligning the contacts with the terminals. Press it gently until it is securely in place.

Close the computer case: Once the new battery is inserted, close the computer case and ensure it is properly secured.

Power on the computer: Plug the computer back into the power source and turn it on. The new CMOS battery should provide power to the CMOS chip, retaining the BIOS settings and allowing the computer to boot normally.

Set BIOS configurations (if necessary): In some cases, the BIOS settings may have been reset due to the battery replacement. If you encounter incorrect time, date, or other BIOS-related issues, enter the BIOS setup by pressing a specific key (such as Del, F2, or F10) during the boot process. Make any necessary adjustments to the settings and save changes before exiting the BIOS.

**By following these steps, you should be able to replace the CMOS battery in your computer and ensure the proper functioning of the BIOS and related settings**.

Precautions During CMOS Battery Replacement

When replacing the CMOS battery in a computer, it’s important to take certain precautions to ensure a smooth and safe process. Here we are giving some precautions to keep in mind:

Shutdown the computer: Before starting the replacement process, shut down the computer properly and disconnect it from the power source. This prevents any risk of electrical shock and protects the components from potential damage.

Precautions During CMOS Battery Replacement
Precautions During CMOS Battery Replacement

Ground yourself: To prevent static electricity from damaging sensitive electronic components, ground yourself by touching a grounded metal object or wearing an anti-static wrist strap. Static electricity can harm the motherboard and other components, so it’s crucial to discharge any built-up static before handling them.

Check for any damage or leakage: Inspect the old battery before discarding it. If you notice any signs of damage, such as leakage, corrosion, or swelling, handle it with caution and dispose of it properly. If the battery has leaked, use gloves and avoid direct contact with the leaked material.

Use the correct battery type: Purchase a replacement battery that is compatible with your motherboard model and follows the manufacturer’s specifications. Using an incorrect battery type or size may lead to compatibility issues or improper functioning.

Verify BIOS settings: After replacing the CMOS battery, boot the computer and check the BIOS settings. Make sure the time, date, and other essential configurations are accurate. If necessary, adjust the settings to ensure proper system operation.

**By following these precautions, you can minimize the risk of damage to your computer components and ensure a successful CMOS battery replacement process**.


In conclusion, the CMOS battery is a small but essential component in the computer world. It serves multiple important functions, including retaining BIOS settings, powering the real-time clock, facilitating the Power-On Self Test (POST), aiding in BIOS firmware updates, supporting security features, and maintaining stability in overclocked systems.

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4 thoughts on “What is a CMOS Battery (CR2302)? Accurate Uses and Replace Process”

  1. untill i read your this inetseting post i completely tired about daily date and time change in my pc. but now i will try your easy way to change this MB battery. thnk u so much admin.


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