The CMOS Battery in PCs: What It Is and Why It Matters

Client: Oglethorpe Sturton And Gillibrand

Oglethorpe Sturton & Gillibrand are understandably proud of their heritage, but it is their forward-thinking approach that lies at the heart of their shared success with clients.

A full-service personal, business and agricultural law firm with offices in Lancaster and Kirkby Lonsdale, Oglethorpe Sturton & Gillibrand has what it takes to deliver the highest quality legal advice to private individuals, businesses and the rural community throughout the Northwest and further afield.

What was the challenge?

Out of the blue, the Managing Partner’s PC would not boot, giving errors regarding the system (CMOS) battery having failed.

The CMOS battery is usually a small, round lithium battery, often a CR2032, which is common in many household electronics. It’s mounted directly onto the motherboard and typically has a lifespan of 5 to 10 years, depending on usage and environmental factors.

The primary function of the CMOS battery is to maintain the BIOS settings when the computer is powered off. Without the CMOS battery, these settings would be lost every time the computer is shut down, leading to incorrect system behaviour.

Another critical function of the CMOS battery is to keep the system clock running. The date and time on your PC are essential for a variety of tasks, and possibly a very little-known fact is that the CMOS battery ensures that the system clock remains accurate, even when the computer is turned off.

What did we do to fix it?

Unlike laptop/tablet or phone batteries, these system batteries are unable to let you know when they are running low, so when they go, they go!

All of our engineers at Q2Q carry spare CMOS batteries in their kit bags for just such an issue, and we were able to attend site within the hour, open up the PC and replace the battery. The PC was back up and running within 15 minutes of arrival.

Naturally, being unable to use your PC is at best, an inconvenience, and at worse mission critical should a meeting or piece of work require it. Having the understanding of these potential issues and the supplies on hand to quickly replace these baby batteries, meant we could have this PC back up and running in the speediest of times.

You’ll likely have seen these exact same coin batteries in your electronic car key fob!
They are also used in slim remote controls, weighing scales, wearable sports monitors and bicycle accessories. They truly are everywhere!