Is cmos battery necessary? (Read This)

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Here is all information about is cmos battery necessary for the pc? The CMOS battery’s job is to keep the CMOS’s minuscule amount of electricity running when the computer is turned off, and the power cord is unplugged, not to power the computer while it is active. This main purpose is to keep the clock running even while the computer is off. Every time you powered on the computer without the CMOS battery, you would have to restart the clock.

is cmos battery necessary for pc

The non-volatile BIOS memory, which retained BIOS settings between reboots, was maintained on older systems by the CMOS battery, supplying the little energy needed to do so. This data is often kept on flash memory on newer devices and doesn’t need to be charged.

Is cmos battery necessary?

A motherboard’s CMOS battery, a crucial component, will emit a beep code when it runs out of power. It is preferable to replace it because it stores BIOS settings in addition to time and date. Similar parameters on modern boards are stored in non-volatile memory, so they can’t be as readily changed.

What Is a CMOS Battery?

Complementary metal-oxide-semiconductor is referred to as CMOS. CMOS RAM, a type of volatile memory, was used in the early days of personal computers to store BIOS settings. A battery is necessary for CMOS RAM because the settings would be lost when the computer is turned off or shows no display without one.

Modern systems no longer employ CMOS RAM. The BIOS settings are saved in non-volatile memory, eliminating the requirement for constant power. Modern UEFI motherboards save settings either in flash memory or the computer’s hard drive. Although these systems don’t require batteries, you can frequently find them there.

How do I know my CMOS battery failed?

The following are signs of a failing CMOS battery:

  • The laptop has trouble starting up.
  • The motherboard makes a continuous beeping sound.
  • The time and date have been reset.
  • Peripherals are unresponsive or respond improperly.
  • Hardware drivers are no longer available
  • You are unable to access the internet

Your BIOS firmware will shut down and resume using the factory default settings if your CMOS battery dies.

Boot up problems and incessant beeping:

Boot up problems and incessant beeping

As we previously said, your computer boots primarily thanks to the BIOS. Your laptop can have an extremely hard time starting without the battery, or it might not start. Another sign of a failing battery is a continuous beeping sound from the motherboard.

Time and date from long, long ago:

You might notice the date and time reset if your laptop boots up. They’ve probably reset to a date that happened a long time ago. The BIOS keeps a real-time clock that tracks the date and time while your machine is off. CMOS maintains that procedure, also sometimes referred to as a real-time clock in and of itself. Therefore, it’s a good indication that the CMOS battery died if the date and time unexpectedly reset.

Keyboard acting wonky:

Your peripheral devices might not work properly if you cannot move the mouse, click on icons, or use the keyboard. Alternately, your peripherals might be out of sync, your cursor might be incorrect, and your key inputs might cause the operating system to behave oddly.

Alternately, the default keyboard configuration has been restored after being changed. Since the BIOS is in charge of handling peripherals during startup, these are all indications of CMOS failure.

Drivers disappear:

A CMOS failure may make any drivers you’ve loaded on your computer, such as those for your home printer, disappear, requiring you to download and install them again.

No internet connection:

If the battery runs out, you might not be able to access the internet. The responsibility for updating network and hardware drivers falls to BIOS. You can sigh relief knowing that most of the time, personal files won’t be lost due to CMOS failure. Nothing stored there is impacted. Once you’ve changed the battery, you may still access all of your photos, movies, and documents.

How to replace the CMOS battery:

It’s time to make your purchase now that you know your computer or notebook will require a new CMOS battery. I choose to go to Amazon and buy a two-pack with free shipping for under $4 if I don’t have to rush and have the patience to wait a few days. If you require one sooner, go to your neighbourhood electronics, home improvement, or superstore and get it for a comparable cost.

Verify the type of battery you’ll be using before you buy. Find this data in your user manual or by opening your case and looking at the CMOS at the top. I have discovered from experience that it is typically a CR2032. I’ve used a CR2016 when needed, but it only has approximately half the life.

  • Disconnect all cords but the electricity.
  • After removing the notebook’s primary battery, Press and hold the computer or laptop’s power button for around five seconds while unplugging the power cable.
  • Take off the screws from the computer’s back.
  • The side panel should be pulled away from the computer’s rear.
  • 5 Find the battery. It is a little, round, shiny battery, as seen above.
  • Remember that batteries are typically put up with the writing side or positive side.
  • Take off the motherboard’s battery.
  • Insert the fresh battery into the same socket as the old one.
  • Change the computer’s side panel.
  • Screw the side panel in place.
  • Reattach all wires, switch on the computer, and set the time.


To summarize the query if a CMOS battery necessary? Your laptop’s BIOS firmware, which is in charge of starting up your computer and configuring data flow, is powered by the CMOS battery. If your laptop has trouble starting up, drivers disappear, or the date and time on your laptop are off, your CMOS battery may have died.

A CMOS battery replacement is a pretty straightforward repair. If you’re experiencing problems rebooting, don’t freak out. Get a screwdriver and a fresh battery and replace the old one before taking your computer for maintenance. It’s a quick and simple DIY project that could help you save much money on labour.

Frequently Asked Questions

Can a computer run without a CMOS battery?

Absolutely yes Even without a CMOS battery, your motherboard and computer can boot just fine. The only drawback is that the time and date will be wrong, and all your BIOS settings will reset. Additionally, you won’t be able to store BIOS settings.

Will removing CMOS battery reset BIOS?

A CMOS battery, which offers a power source so motherboards can save BIOS settings, is not present in every type of motherboard. Remember that your BIOS will reset when you remove and replace the CMOS battery.

How long does the CMOS battery last?

A battery is necessary for CMOS RAM because the settings would be lost when the computer is turned off without one. Modern systems no longer employ CMOS RAM. The BIOS settings are saved in non-volatile memory, eliminating the requirement for constant power.

How long does the CMOS battery last?

A CR2032 lithium coin cell typically serves as the memory battery (also known as the motherboard, CMOS, real-time clock (RTC), or clock battery). Unplugging the power supply unit (PSU) or turning off the PSU power switch, this cell battery has an anticipated lifespan of three years.

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