Every computer has a small battery on its motherboard. It is used to provide power to the CMOS on the computer. CMOS (Complementary Metal Oxide Semiconductor) chip on your computer remembers everything like Hard Disk, time and date etc. The CMOS battery provides power to the CMOS chip always i.e., even when your computer is OFF to save all the settings. So, it is important at the time of booting of your computer and other tasks.laptop battery

CMOS battery is a small battery fitted on the motherboard of your computer. It has a life of around five years. You need to use the computer regularly to extend the life of the CMOS battery. The computer power supply increases availability of standby current and hence increases life of the battery.

 If the computer is not plugged in regularly, the life of the battery is normally 3 years. However, the life of the battery gets extended to 5 years when you use it regularly. The battery provides power to CMOS memory and real time clock.


Signs of a CMOS battery failure

 cmos battery structure

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It is a 3V battery. If the voltage drops between certain levels, your computer loses the memory. The CMOS settings like date and time gets changed. In some instances, the date and time gets set to factory default. For example, your computer date and will be set to factory settings like Thus 12/01/2008.

  • All of the settings like HDD type, FDD, NUMs lock, etc in the computer setup will be changed. It may be causing booting problems since your computer do not remember information about the hard disk.
  • Your computer will show the message like: Booting Error, unable to detect hard disk.
  • Your computer may be shutting down and will not allow you to perform any task.
  • Your computer may be too slow. It may be due to wrong time and date. It is time to replace to the CMOS battery to correct these issues.
  • Some of the drivers may be missing or may not work properly. So, you may not be able to take printout on printer. Even if you install the printer driver correctly, your computer may keep on showing message “can’t find printer”.
  • Your mouse may not respond properly. You may feel that your mouse might have got damaged and will readily order for a mouse. It can be solved by simply replacing the CMOS battery. Therefore, before ordering a mouse, you can try the same mouse on another computer to check if it is actually defective. So, you can save your hard earned money.
  • You may not be able to connect to the Internet. It keeps on showing error to connect the internet. You need to check whether time and date are correct. If the date and time are wrong, try correcting. Then, check again, if the computer is connecting to the Internet, you need to replace the CMOS battery.
  • If you are hearing constant beeping sound when working with your computer, it is a sign that you need to replace the CMOS battery.
  • The computer will also display CMOS battery failure, CMOS Read error, or CMOS checksum error etc. You need to switch on your computer and leave it for a day. If the computer is not showing the errors after rebooting, the CMOS battery is charging. Otherwise, you need to replace the CMOS battery.


Where to buy the CMOS battery for your laptop or desktop?

 cmos battery failure

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You can make a visit to the local computer store to buy a CMOS battery for your computer or laptop or netbook. You can also buy the coin shaped 3V CMOS battery from online stores. The premium CMOS battery is advised for trouble free operation of the computer. It will last for more than 5 years. However, you can also buy a cheaper version of the 3V Lithium battery for your computer. But, its life is very less when compared to the premium version. Therefore, it is suggested to buy a premium version of the battery for your computer.

Before buying a battery, you are advised to check the rating of your computer CMOS battery and order the same one from online store. The online stores usually deliver the items within 5 to 7 days. If you can’t wait that long time, you can also buy the premium version from the local computer store.


How to Replace CMOS battery in Your Computer?

 replace battery failure


Replacing a CMOS battery in your laptop or computer is easy. If you are new to the computer or laptop, you can also seek the help of local computer technician to replace the computer battery.

Items required for replacing the computer CMOS battery

  • Screw driver set
  • Multimeter

Steps to replace the CMOS battery

You need to first switch off the computer or laptop. Remove the power cord from the mains. It is also suggested to remove the battery pack from your netbook or laptop. You need to remove the cover of the CPU or laptop using a star screw driver. You can find a button type CMOS battery on the motherboard of your computer or laptop. You can use the flat type screw driver to slowly lift the button    cell from the motherboard.

You can use the multimeter to check the voltage of the battery using a digital multimeter. If the voltage is less than 3V, your computer will not remember the CMOS settings. It is time to replace the old battery with new CMOS battery.

After replacing the battery in the same orientation, you can replace the computer cover and tighten the screws.

You can plug in the power cord and switch ON the computer to check if it is working properly. However, after replacing the CMOS battery you need to enter the correct BIOS settings. After booting your computer, you need to enter the correct date and time.

Now your computer or laptop is ready for regular use.

It is suggested to use the computer regularly to extend the battery life.

 About the Author:

Author Bio: Tahmina Jannat  is a tech journalist and blogger on  ProTechSourced.com – At ProTechSourced we provide you with all the latest information on technology related stories, products and much more.


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