Why Do Desktop Computers have Batteries?

Why Do Desktop Computers have Batteries?
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Unknown to many owners of these products, many electronics including computers, camcorders, and digital cameras have a small battery in them to keep track of the time. This is how an electronic device knows the date and time and can store settings and other information chosen by the user of the equipment.

When the battery on a motherboard dies, it needs to be replaced just like a watch battery. Failure to replace it can lead to boot errors and other computer problems. Learn why your PC needs a battery and what it does to keep your computer running smoothly.

Why Computers Have Batteries

When you use your computer, you certainly have noticed that every time you turn it on, it knows the correct date and time. Your PC stores date and time information each time you save a file. The reason your computer can do this is because there is a battery on the motherboard.

Every motherboard has a small quartz clock built into it to communicate to the computer and operating system the correct date and time (see Figure). Known as a Real Time Clock (RTC), this clock allows several features of your computer to run correctly.

The battery on your computer’s motherboard has a life of about 5 to 7 years depending on how you use your PC. This time period is longer than most computers last so many owners are unaware that a battery even exists in their PC and rarely have to change it before junking the computer for a new one.

However, the battery in your PC does more than just run the clock. The battery also helps to store your computer’s BIOS information. The Basic Input/Output System (BIOS) is a set of instructions that help your computer boot up. The BIOS stores information about your computer’s disk drives, memory, boot options, and more. Without this information, your computer might not start up correctly.

Since you turn off and sometimes unplug your computer, your PC needs a battery to store data in the volatile memory where the BIOS information is stored. When the battery goes dead, the BIOS can no longer store this information. This can lead to boot errors if the boot process is dependent on the information it gets from your PC’s BIOS.

Some modern computers store this BIOS information in non-volatile memory. This means that the PC does not need a battery for the BIOS memory to remain intact. Even if the battery goes dead, the PC would boot without any problems.

However, the RTC would cease to function and your operating system wouldn’t be able to tell the date and time. Consequently, even computers that take advantage of non-volatile memory still need a battery for the internal quartz clock.


Although not considered a major component in a computer, your PC’s battery is often necessary to help the computer boot up. Powering not only the internal quartz clock but also the volatile BIOS memory, the battery on your motherboard is necessary to keep your computer running smoothly. If your operating system consistently shows the wrong date and time, replace the battery on your motherboard and see if the error disappears.