What is a CMOS Battery? A CMOS (Complementary Metal-Oxide-Semiconductor) battery is a small, coin-shaped battery found on a computer’s motherboard. It provides power to the CMOS chip, which stores important system information such as the date, time, and hardware settings in the CMOS memory. We explain what a CMOS battery is for, and how to replace is when it goes flat. Explore the functions, types, and lifespan of CMOS batteries in computers. Learn how these small batteries power BIOS firmware and maintain system settings when your computer is turned off. Learn about the CMOS battery, a small coin cell that powers the CMOS chip on your motherboard and stores your BIOS settings and RTC. Find out how to troubleshoot and replace a weak or dead CMOS battery and avoid common issues.
