Why does my PC say “CMOS Low Battery?”

Rene Gatdula March 30, 2012

Every time I open my PC it says I have “CMOS Low Battery” what does that mean?

  1. kasyap
    August 2, 2012 at 6:59 am

    just replace the CMOS battery( you will get it from some PC shops) open your CPU and see on your system mother board you can see the battery there just replace that... thats it :)

  2. Oron Joffe
    March 30, 2012 at 9:26 pm


    Most motherboards use "button batteries" to back some basic settings (no. and type of hard discs on the PC etc) and to keep the clock running. Thes battery type is often CR2016 or CR2032 (the type is imprinted on the battery).
    Remove the battery, taking note of it polarity, get a new one of the same type and fit it. You will then need to enter the BIOS and reset the basic settings (there's ususally a "load safe settings" option which you can choose, and you'll be up and running in no time.

  3. Matt.Smith
    March 30, 2012 at 6:02 am

    The CMOS battery is a small battery located on the motherboard. It provides power to the computer's motherboard so that very basic settings, like the date/time and the boot order, are saved to memory even if the computer is unplugged.

    It is probably running out of juice. So you need to find it and replace it. This should not be too difficult - it's almost always one of the circular batteries, the kind you would find in a watch. 

  4. Indronil Mondal
    March 30, 2012 at 5:41 am

     If your computer is losing its time or date settings, or you are receiving a message CMOS Read Error, CMOS checksum error, or CMOS Battery Failure,
    try leaving the computer on for 24-hours. In some cases this can
    charge the battery and resolve your issue. This often resolves CMOS
    battery related issues when a computer has been left off for several

    If this does not resolve your issue follow the below steps.

    Locate your CMOS batteryObtain battery informationRemoving the battery
    Insert the new batteryEnter CMOS valuesrestart the computer all will be fine