failed CMOS battery

What is a typical SYMPTOM of a CMOS BATTERY FAILURE?

Most people never think about what happens when a CMOS battery, also known as coin-cell battery (CR2032), dies. But the CMOS battery is a critical component of your computer. The CMOS battery is a tiny part, seemingly unimportant, but when it fails, your computer no longer shows the correct time, and it will lead to severe issues with your laptop or desktop computer. But, what are the signs of a CMOS battery failing?

I have researched issues related to CMOS battery failures to help you recognize the telltale signs of a dying CMOS battery. First, I will provide you with the necessary information to help you understand the problems a failing CMOS battery can cause in your computer. Then, we will discuss its primary function, what will happen if the CMOS battery dies and how to replace it.

My goal is to help you understand the problems a failed CMOS battery can present. I also hope that this article will help you prevent the problems that a dead CMOS battery may cause.

What is a typical symptom of a CMOS battery failure?

Several telltale signs indicate a dying CMOS battery, but the most common symptom that most people experience is an incorrect date and time. Unfortunately, it is also represented by a consistent date and time reset even if you set the correct date and time in the BIOS (Basic Input/Output System).

Common symptoms of a failing or dying CMOS battery are:

  • Booting issues
  • Failing or disappearing drivers
  • Beeping noise from motherboard
  • Random shutdowns
  • Checksum error
  • Unresponsive peripherals
  • Network or Internet connectivity issues
  • Various hardware failures.

All of the above symptoms indicate a CMOS battery failure. The CMOS failure tells you that you need to replace the CMOS battery to keep your computer running optimally.

dead CMOS battery

How can you detect if your CMOS battery is dead?

In older computers, you can detect if your CMOS battery is dead by displaying the incorrect time. However, even after setting the correct date and time, your computer won’t retain it with a dead CMOS battery.

It’s easier to detect if your CMOS battery failed in newer motherboards because it will display a warning if the voltage in your CMOS battery is low.

What are the possible consequences of a CMOS battery failure?

One of the possible consequences of a CMOS battery failure is losing RTC (Real-time Clock) configuration. The CMOS battery plays a vital role in keeping your BIOS settings and clock configurations. A working CMOS battery ensures that these configurations are stored even when turning your computer off or unplugging the power cord.

Another serious consequence of a dead CMOS battery is that you will lose all of your BIOS settings. Also, your computer will be stuck at the POST unless you click the BIOS settings shortcut.

Usually, at POST (Power-on Self Test), the BIOS will report that the CMOS battery is not inserted or has depleted.

Can a dead CMOS battery cause a PC (or laptop) not to turn on?

A dead CMOS battery can prevent a PC or a laptop from turning on. This is very common with older computers. But sometimes, even a brand new laptop may ship with a dead CMOS battery. When that happens, you won’t be able to boot up your laptop.

If you have a new computer with a dead CMOS battery, you could try to remove the batter, leaving it out for a few seconds, then put it back to see if it resolves the issue.

Can a dead CMOS battery stop a computer from booting?

A dead CMOS battery can stop a computer from booting. Most laptops and desktops require a working CMOS battery for boot. The CMOS battery maintains the computer date and time required for the computer to boot up.

What happens if I boot my computer with a failed CMOS battery?

With modern ATX motherboards, your computer will boot even with a failed CMOS battery. However, if you have an older computer with a motherboard where the power is switched from the power supply, a dead CMOS battery will cause the CMOS/BIOS/UEFI settings to be cleared and set to default.

It should boot normally if your laptop or desktop computer can boot with the default CMOS/BIOS/UEFI settings. However, when booting like this, the system time may be off. And if you have special boot settings such as a hardware RAID setup, the computer may become unbootable (unable to find/boot OS) until the failed battery is replaced and the correct settings are restored.

Can a PC run without a CMOS battery?

A PC can run without a CMOS battery. But, the CMOS battery plays an essential role in running your PC. For example, the motherboard won’t retain the system time or remember any BIOS changes without a CMOS battery. Nevertheless, the PC will work without a CMOS battery.

Does every motherboard use the same CMOS battery?

Today, virtually every motherboard uses the same type of CMOS battery. The CR2032 battery is used on modern motherboards. Laptops and desktop computers use a CR2032 coin battery. These lithium coin batteries have 3 volts and 235 mAh.

What if there is no CMOS battery on the motherboard?

The computer will still boot without a battery on the motherboard. This is because manufacturers install a CMOS battery. If you get a computer without a CMOS battery on the motherboard, you should contact the manufacturer.

But, if your computer isn’t brand new and the CMOS battery is missing, you can buy a replacement battery. You need to buy a CR2032 coin lithium-ion battery.

What is the reason CMOS battery keeps dying?

If a CMOS battery keeps dying, your motherboard may have a bigger problem. A CMOS battery should last at least five years, and often it lasts much longer.

A faulty motherboard could result in a CMOS battery dying unusually fast. Unfortunately, if you have a faulty motherboard, you may have to replace it.

What drains CMOS battery?

A constant small load from the motherboard can drain a CMOS battery. For example, a motherboard that isn’t grounded properly can drain the CMOS battery. Therefore, if your CMOS battery is drained fast, check your motherboard.

Can CMOS battery cause no display?

A dead CMOS battery can cause no display. With a failed CMOS battery, the BIOS loses its settings. Therefore, a faulty CMOS battery may cause a blank screen, but it’s unlikely. Instead, the computer monitor will likely display something like stop and wait for a user input, or date and time not set or checksum error.

A black screen is more likely a display hardware problem on the computer no a dead CMOS battery. Even if you hear some beeps, it is more likely a problem with the actual display on the desktop or laptop. Try plugging in another external display to test if you don’t hear any beeps. You should at least hear the fan running unless your computer doesn’t have one.

But, if your computer has a display problem due to a failed CMOS battery, it’s a simple fix. Just replace the dead CMOS battery with a new CR2032 lithium-ion battery.

Will a dead CMOS battery prevent power on?

A dead CMOS battery won’t prevent power on. Because the role of the CMOS battery is to keep the computer date and time up to date, a failed CMOS battery will not prevent power on.

The BIOS won’t retain its settings when the CMOS battery is dead.

How can a CMOS battery be replaced in a PC without losing CMOS contents?

The simplest way to replace a CMOS battery without losing CMOS contents is to swap the battery while the power is on.

But, before you change the CMOS battery, it’s a good idea to take a photo of CMOS/BIOS/UEFI setting screens with your phone. This is a good practice even if you know each setting.

Make sure you swap the CMOS battery quickly. Use a non-conductive tool to remove the dead battery. Always make sure you work in a well-lit environment. Make sure you are grounded before removing the CMOS battery to reduce static electricity.

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George Meszaros is the editor and co-founder of Success Harbor where entrepreneurs learn about building successful companies. Success Harbor is dedicated to document the entrepreneurial journey through interviews, original research, and unique content. George Meszaros is also co-founder of Webene, a web design and digital marketing agency.