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There are several reasons why your computer's CMOS battery may need to be replaced. This guide explains why a replacement may be necessary and the steps to resolve the issue.
Why Do I Need to Replace My CMOS Battery?
The computer keeps losing its time or date settings.
An error or warning message, such as one of the following, appears when the computer starts:
CMOS Read Error
CMOS Checksum Error
CMOS Battery Failure
System battery voltage is low
If you experience any of the problems or messages listed above, you may need to replace the CMOS battery. The replacement process is explained in the following sections.
Locate Your CMOS Battery
Open the computer case and locate the battery on the motherboard, ensuring that it is accessible and can be removed. Most modern computers use a coin-cell CMOS battery, such as the CR2032 battery shown in the picture.
If you cannot locate the CMOS battery, refer to your motherboard documentation or contact your computer manufacturer. If you no longer have the motherboard documentation, you can probably find it online.
Obtain Battery Information
Unfortunately, most manufacturers do not specify the exact type and model of the CMOS battery. Once you locate the battery, we recommend writing down its specifications, including voltage, chemistry, and wiring. If possible, remove the battery and take it to a retail store.
Removing the Battery
If your computer uses a coin-cell battery, removing it is relatively simple. Use your fingers to grip the edge of the battery and pull it up and out of its socket. Some motherboards have a clip that holds the battery in place. If your motherboard has this clip, you may need to use one hand to move the clip upward while using the other hand to remove the battery.
Unfortunately, not all CMOS batteries are removable. Some manufacturers only allow a replacement battery to be added. If your computer does not have a coin-cell battery, refer to your documentation or contact your computer manufacturer for further assistance.
If your computer's motherboard does not have a removable battery, you may need to set a jumper on the motherboard to install the new battery.
Insert the New Battery
After purchasing a new battery, remove the old one and replace it with the new battery, or insert the new battery into the secondary battery socket on the motherboard.
Enter CMOS Values
Once the battery has been replaced, turn on the computer and reset the CMOS values to their defaults. After entering all the values, make sure to save the settings before exiting. Many CMOS setup utilities allow you to press a key, such as F10, to save the values and exit in one step.
Bad Hardware
If you continue to receive the error after following all the steps above, this may indicate a more serious problem. The most likely causes are a faulty power supply or motherboard. You may need to replace the power supply or motherboard to resolve the issue. At this point, we recommend taking your computer to a repair shop so the issue can be diagnosed.
