The CMOS battery is an essential piece of hardware in many computers. Its main function is to provide power to the CMOS chip, which stores important BIOS settings. Without a functioning CMOS battery, the computer would be unable to remember these settings and would have to be reconfigured every time it is turned on. While CMOS batteries are designed to last for many years, it is not uncommon for them to fail before their expected lifespan. In most cases, a CMOS battery will last for several years without issue. However, if the computer is used frequently or is subject to extreme temperatures, the battery may not last as long. If a CMOS battery does fail, it is usually not a major problem.