Why Are There Coin Batteries on Your Computer Motherboard? Here’s Why

How the Computer Resets BIOS Time and Settings If the Battery Runs Out

When the coin battery is discharged, the motherboard loses the power needed to store the BIOS/UEFI settings and the time when the computer is turned off. Consequently:

• Time and Date Settings: The BIOS cannot maintain accurate time and date. Each time the computer is turned on, the BIOS will reset the time and date to the default values, usually the factory date or the year 1970.
• BIOS/UEFI Settings: All BIOS/UEFI configurations that have been customized by the user, such as boot sequence, overclocking settings, RAID configurations, etc., will be lost and returned to factory settings. This can cause the device to not work as expected, and in some cases, the computer may not boot properly.

A Real Example of a Problem Arising from a Depleted Coin Battery

• Boot Failure: A user reported that every time their computer was shut down, the boot order changed and the computer could not find the operating system. After investigation, it was found that the coin battery on the motherboard was dead. Each time the computer is shut down, the BIOS settings are reset, resulting in the boot order returning to default, which does not match the existing operating system configuration.
• Network and Security Issues: A network administrator finds that computers on his network often experience authentication and certificate validation issues. After some investigation, it was discovered that many computers had inaccurate timing due to the coin battery being depleted. Inaccurate timing causes security certificates to be considered invalid, thus preventing access to some network services.
• User Inconvenience: A user complained that every time their computer was turned on, they had to manually reset the time and date. This is a hassle especially because some apps like calendars, emails, and certain software rely on accurate timing. Upon inspection, it was found that the coin battery had run out and needed to be replaced.

How Long Do Coin Batteries Last?

Factors Affecting Coin Battery Life

The battery life  of a coin on a motherboard can be affected by several factors, including:

1. Battery Quality: Batteries from well-known brands such as Duracell, Panasonic, or Energizer usually have better quality and a longer lifespan than unbranded or low-cost brand batteries.
2. Ambient Temperature: Coin batteries installed in environments with extreme temperatures (too hot or too cold) tend to experience a faster degradation in performance and lifespan.
3. Computer Usage: The frequency of computer use also affects battery life. A computer that is turned off and turned on frequently will drain battery power faster than a computer that is turned off infrequently.
4. Motherboard Quality: Some motherboards may have larger power leakage, which can drain the coin battery faster.
5. BIOS/UEFI settings: Certain settings on the BIOS/UEFI that require more power can also speed up the drain of the coin battery.

Average Coin Battery Life and How to Know When It’s Time to Replace

The average battery life of a coin on a motherboard is about 3 to 5 years. However, this lifespan can vary depending on the factors mentioned above.

How to Replace a Coin Battery

Replacing the coin battery on the motherboard is a fairly easy task and can be done on your own. Here are the steps that can be followed:

1. Turn off and unplug the computer: Make sure the computer is turned off and not connected to a power source.
2. Open the Computer Case: Remove the computer case cover to access the inside of the motherboard.
3. Find Coin Batteries: Look for coin batteries that are usually near the bottom or center of the motherboard.
4. Remove Old Batteries: Carefully, use a small tool such as a flathead screwdriver to remove the battery from its slot.
5. Install New Batteries: Insert a new coin battery into the slot paying attention to its polarity. Make sure the batteries are properly installed and that the contacts are perfect.
6. Reinstall the Case: Once the battery is installed, close the computer case again and connect the power cable.