Can a Laptop Start Without CMOS Battery? (How It is Possible!)

Published on: September 20, 2022
Written by Jonas Frank / Fact-checked by Nova Scarlett

In order to answer this question, we must first understand what a CMOS battery is and what it does. A CMOS battery, also known as an RTC battery, provides power to your computer’s Real Time Clock (RTC) and allows it to keep track of time even when the computer is turned off. Without a CMOS battery, your computer would not be able to remember the current date and time.

can a laptop start without cmos battery

Now that we know what a CMOS battery is and what it does, we can answer the question of whether or not a laptop can start without one. The short answer is yes, a laptop can start without a CMOS battery; however, you will not be able to set the current date and time without one.

The short answer is yes, a laptop can start without a CMOS battery. However, there may be some consequences that you should be aware of before proceeding. Without a CMOS battery, your laptop will likely lose some important information every time it is powered off.

This includes the date and time, as well as any custom settings you may have in your BIOS. As such, you’ll probably want to set these items again each time you power on your laptop. Additionally, your laptop may have trouble maintaining an accurate clock speed without a CMOS battery.

This could lead to performance issues or even data corruption over time. Therefore, it’s generally not recommended to run a laptop without a CMOS battery for extended periods of time. You have to know that slow charging your device’s battery can help extend its overall life.

What is a CMOS Battery?

A CMOS battery is a device that provides power to your computer’s CMOS chip. The CMOS chip contains information about your computer’s configuration, including the date and time. Without power, the CMOS chip would lose this information.

The CMOS battery is usually a small, round, coin-like button cell battery. It is typically located on the motherboard near the BIOS chip. When you replace or upgrade your computer’s motherboard, you’ll need to transfer the old battery to the new board.

If your computer is having problems keeping accurate time or losing BIOS settings, it could be due to a dying CMOS battery. Replacing the battery is usually a quick and easy fix.

How Long Does a CMOS Battery Last?

A CMOS battery, or complementary metal-oxide-semiconductor battery, is a small lithium-ion battery that provides power to a computer’s basic input/output system. If a lithium-ion battery is charging, it will generate more heat than when it is not charging.  The average lifespan of a CMOS battery is between three and five years. However, some batteries may last much longer – up to 10 years – while others may only last one or two years.

how long does a cmos battery last

How to Start PC Without CMOS Battery?

If your PC has a removable CMOS battery, you can try starting the computer without it. Here’s how:

1. Disconnect the power cord from your PC.

2. Remove the CMOS battery from its slot on the motherboard.

3. Wait 10-15 seconds, then reinsert the battery and connect the power cord.

4. Turn on your PC and see if it starts without issue.

If not, you may need to replace your CMOS battery or consult a qualified technician for further diagnosis.

How to Reset BIOS on Laptop Without CMOS Battery?

If your computer is having trouble booting up, it may be because the BIOS (Basic Input/Output System) needs to be reset. The BIOS is a chip on the motherboard that stores basic information about the computer’s hardware and tells the computer how to start up. Sometimes, you may need to reset the BIOS in order to fix a problem or change a setting.

You can usually reset the BIOS by pressing a key during startups, such as F1, F2, or DEL. However, if your BIOS is password-protected, you’ll need to enter the password before you can access the settings. If you don’t know the password, you’ll need to clear it by removing the CMOS battery from the motherboard for 10-15 minutes.

Once you’ve accessed the BIOS settings, look for an option to reset them to default values or factory settings. Save your changes and exit from BIOS; your computer should now boot up normally. If not, you may need to try clearing the CMOS battery again or contact your computer’s manufacturer for further assistance.

No CMOS Battery on Motherboard

If you have a computer that won’t turn on, or if your BIOS settings keep resetting themselves, it’s possible that your CMOS battery is dead. This battery is what provides power to the Complementary Metal Oxide Semiconductor (CMOS), which stores all of your BIOS settings. Without this battery, your computer won’t be able to remember any of its custom settings.

The CMOS battery is usually a small, round coin-sized cell that can be found on the motherboard. If it’s not clearly labeled, you may need to refer to your motherboard manual to find its location. Once you’ve found it, you can remove and replace the battery just like any other coin cell battery.

You’ll want to use a Phillips head screwdriver for this task. Be sure to unplug all cables from your computer before opening it up! Also, touch something metal before handling any internal components, such as the CMOS battery, to ground yourself and avoid static discharge damage.

Once you’ve replaced the CMOS battery, reassemble your computer and plug it back in. Your BIOS settings should now be saved and your computer should operate as normal again.

What Happens If CMOS Battery is Low?

If your CMOS battery is low, it could affect the normal operation of your computer. The CMOS battery provides power to the Complementary Metal Oxide Semiconductor (CMOS), which is responsible for storing information like the system time and date, hard disk parameters, and other configuration settings. If the CMOS battery is not providing enough power, the CMOS chip may lose its ability to hold onto this information.

As a result, you may see error messages or experience unexpected behavior when you start up your computer. In some cases, you may even be unable to boot into Windows. Fortunately, replacing the CMOS battery is usually a pretty easy fix.

You can purchase a new battery from most electronics stores or online retailers. Once you have the new battery, simply remove the old one and install the new one in its place.

CMOS Battery Low

Your computer’s CMOS battery is responsible for keeping track of the time and date, as well as other system settings. If your CMOS battery is low, it can cause problems with your computer’s ability to keep accurate time and date information. In some cases, a low CMOS battery can also lead to boot errors or instability.

If you suspect that your CMOS battery may be low, there are a few things you can do to check. First, try resetting the BIOS to default values. If that doesn’t work, you can try removing and re-seating the battery.

If neither of those options works, you’ll need to replace the battery. Replacing the CMOS battery is relatively easy – just follow your computer’s manual or look up a tutorial online for your specific model. Once you have the new battery in place, be sure to set the correct time and date before rebooting your machine.

cmos battery low

CMOS Battery Laptop

Your laptop has a CMOS battery, which is used to power the Real Time Clock (RTC) on the motherboard. The RTC keeps track of time, even when the computer is turned off. Without the CMOS battery, your laptop would forget what time it is every time you turn it off.

The CMOS battery is a lithium-ion battery, which means that it will eventually need to be replaced. How often this needs to happen depends on how often you use your laptop and how long you keep it turned off. If you use your laptop regularly and only turn it off for short periods of time, then you may never need to replace the CMOS battery.

However, if you don’t use your laptop very often or if you keep it turned off for extended periods of time (weeks or months), then the CMOS battery may die sooner. If your laptop’s CMOS battery does die, don’t worry – it’s easy to replace! Just follow these steps:

Step 1 Power down your laptop and unplug all cables from its body.
Step 2Remove the back panel – this will usually just require removing a few screws. Be careful not to lose any small pieces like washers or stand offs!
Step 3Locate the CMOS battery on the motherboard – it will look like a small coin cell battery (see image below).
Step 4Unscrew the old CMOS battery and remove it from the socket on the motherboard Gently pry the battery out with a small flathead screwdriver necessary.
Step 5Install the new battery placing it into the socket and tightening the screw Make sure that the positive(+)(or red)side is facing up.
Step 6Replace the back panel and screws.
Step 7Power on the laptop to check that the date and time are correct If not go into BIOS set up and correct.
Step 8You’re done!

HP Laptop Without CMOS Battery

If your laptop is running low on power, you may be considering removing the CMOS battery. This can be a great way to save energy and prolong the life of your laptop’s battery. However, there are some things you should know before you remove the CMOS battery from your HP laptop.

The CMOS battery helps to keep the clock on your laptop running accurately. Without this battery, the clock will reset every time you reboot your computer. This can be frustrating if you’re trying to keep track of time or schedule appointments.

Additionally, removing the CMOS battery will disable any passwords that you have set up on your computer. If you have a password-protected BIOS, for example, you’ll need to enter it again after removing the CMOS battery. Make sure you know all of your passwords before taking out the CMOS battery!

Finally, remember that removing the CMOS battery is not a permanent fix for low-power issues. If your laptop continues to run low on power after removing the CMOS battery, there may be another issue at play. Consider taking your laptop to a professional for diagnosis and repair if this problem persists.


Does a Laptop Battery Affect Performance?

Laptop batteries are designed to provide a consistent level of power output over their lifetime. However, as the battery ages, its performance may degrade. This can result in reduced battery life and reduced performance when using the laptop on battery power.

In some cases, it may be necessary to replace the battery in order to restore full performance.

Do I Need a CMOS Battery to Start My Laptop?

No, you do not need a CMOS battery to start your laptop. The CMOS battery is only required if you want to save the settings in your BIOS. Without the battery, your laptop will still start up and run normally.

Why is My CMOS Battery Not Working?

One of the most common reasons a CMOS battery may stop working is because it has become discharged. This can happen if the computer is left unplugged for an extended period of time, or if there is a problem with the power supply. If the battery is not working, it will need to be replaced. When it comes to batteries, the temperature can have a significant impact on their lifespan and performance.

Another reason the CMOS battery may stop working is that it has become disconnected from the motherboard. This can happen if the computer is moved around a lot, or if something hits it hard enough to dislodge it. If this happens, you’ll need to open up your computer and re-connect the battery.


As long as your laptop has a working AC adapter and power cord, you can still use it without the CMOS battery. The only time you would need the battery is if you want to change the BIOS settings or if the computer is having trouble starting up.

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