How to Tell If Your Laptop CMOS Battery Needs Replacing

Your laptop's CMOS battery is small, but when it fails, it can cause some frustrating and confusing problems. Here are the most common signs that your CMOS battery needs replacing.

1. Date and Time Keep Resetting

Every time you start your laptop, the clock resets to a default date (often January 1, 2000 or a similar date). This is the most common and obvious sign of a dead CMOS battery.

2. BIOS Settings Won't Save

If your custom BIOS settings (like boot order or fan settings) keep reverting to default after every shutdown, the CMOS battery is no longer able to retain that information.

3. Boot Error Messages

Seeing errors like "CMOS Checksum Error", "CMOS Battery Failure", or "Press F1 to continue" on startup? These are direct warnings from your system that the CMOS battery is failing or already dead.

4. Frequent Boot Failures

A failing CMOS battery can sometimes cause your laptop to struggle to start up, or behave unpredictably during the boot process.

5. Hardware Not Detected Correctly

In some cases, a dead CMOS battery can cause your system to fail to recognize connected hardware, such as drives or peripherals, since the BIOS loses its configuration.

 If your laptop is showing any of these signs, browse our selection of CMOS replacement batteries to find the right one for your model.