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WHAT DOES THE CMOS BATTERY DO AND WHAT ARE THE DEAD CMOS BATTERY SYMPTOMS?

The RTC CMOS battery, also known as the Complementary Metal Oxide Semiconductor battery, is used for maintaining basic computer functions such as powering the real-time clock (RTC) and maintaining the BIOS (Basic Input/Output System) settings when a computer is powered off. The CMOS battery is crucial for the smooth operation of your computer.

On older machines, a failed CMOS battery can lead to boot errors and even prevent a computer from booting. This is a common symptom when a CMOS battery dies. If your CMOS battery dies, it can cause significant issues with your computer’s operating system. On newer machines, a dead CMOS battery can reset the clock to a random date which can then prevent programs and apps from functioning correctly. Time checks can be used by apps for license verification, software updates, and data logging.

What does the computer motherboard battery do?

In the past, BIOS settings were stored in a CMOS memory chip, powered by an independent power source – a CMOS battery. With the advent of non-volatile memory, the need for recharge disappeared. However, when a CMOS battery failure occurs, it can disrupt these settings.

Why do manufacturers continue to make motherboards with coin cell batteries?

It’s all about the system’s real-time clock (RTC). A computer needs an internal clock to run constantly and show the correct time when powered on. Devices like wristwatches have a quartz-based movement which can recharge with continuous movement. This is not possible with computers as they are stationary most of the time. A CMOS battery keeps the time going while your computer, laptop, or tablet is powered off and unplugged from the power cord.

Signs of a Dead CMOS Battery

If the CMOS battery fails on an older computer where BIOS settings are stored to the CMOS chip, then you will see error messages during the boot cycle:

• CMOS Battery Failure
• CMOS Read Error
• CMOS Checksum Error
• Other CMOS or Clock Related Errors

These are signs of a dying CMOS battery. Some older computers may fail to recognize internet computer components and therefore won’t boot correctly.

Newer computers that store BIOS settings in non-volatile memory will not show you any errors, but the system clock will be reset during every reboot. This can be a sign of a failing CMOS battery.

Some systems may not boot at all and only show a sequence of blinking lights or short beeps. This sequence needs to be decoded via the repair manual or an instruction manual which can be downloaded from the manufacturer’s website.

Types of CMOS batteries

Most desktop computers have a coin cell or a button battery which is similar to the one in wristwatches and remote controls. Typically this is a silver round CR2032 battery that can be easily spotted and replaced. This is the most common type of CMOS battery you’ll find in a computer.

Some desktops and high-end motherboards have a CMOS battery that is wrapped in shrink or electrical tape and comes with a specific connector. They can be yellow, blue, black, or any other colour and require a replacement that is an exact match. Electrical tape has to be carefully removed in order to determine the battery type underneath. A common battery is CR2032, but it is also possible to have CR2016 or CR2025.

Most laptops use a battery that is wrapped in electrical tape with leads and a connector. Connectors can vary by make, model, and specifications of each computer based on the motherboard used by the manufacturer. Common coin cell batteries found inside laptops are CR2032, CR2025, CR2016, CR1220, ML1220, CR1632, CR1616, and custom Ni-MH batteries. Coin cell batteries have an output of around 3V and custom Ni-MH batteries can be between 2.4v and 7.2v. The difference between the coin cell batteries is their diameter and thickness.

Picking a Correct CMOS Battery

Knowing the exact make and model of your laptop is the easiest and most precise way to find a replacement battery. Our database contains thousands of laptops dating all the way back to the 1990s.

If you do not know your computer’s make and model or it is not in our database then you can open your computer and locate the original failed CMOS battery to look for a replacement. This is a common step when you need to replace the CMOS battery.

You will need to know 4 things in order to pick a correct RTC CMOS Battery:

• Connector – There are many connectors that are not cross-compatible with each other. Our website provides detailed 3D drawings of each connector so you can easily determine the correct one.
• Polarity – Each connector has colour-coded leads coming out of it. Pay attention to the red and black ones. Red is the positive (+) and black is the negative (-). You have to make sure that the replacement battery has them in the same exact order. There may also be a white-coloured lead which is the same as a black negative lead (-).
• Length of leads – Measure the length of the leads and purchase a replacement with the same or longer leads.
• Battery Type – Carefully peel off the electric film to see which battery is underneath. Common coin cell batteries found inside laptops are CR2032, CR2025, CR2016, CR1220, ML1220, CR1632, CR1616, and custom Ni-MH batteries.

Once you know all 4 of these specifications, you can build your own battery via our Easy Battery Builder.

Please remember to use caution when working with electrical components and batteries. Keep batteries away from children and turn off your computer prior to performing any repairs. Consider taking your computer to a professional repair shop if you are not comfortable with battery replacement. Remember to check the manufacturer’s service manual to see where the battery is located and how to access it. Discharge any static electricity before touching any computer components.

HOW TO FIND THE CORRECT CMOS BATTERY?

Finding the right CMOS battery for your computer can be challenging due to different battery types and connectors released over the last 30 years. Brands like Acer, Asus, Alienware, Dell, HP, Toshiba, IBM ThinkPad, and Sony use proprietary battery connectors for their computers. The CMOS battery is a crucial component that maintains your BIOS settings and powers your computer’s CMOS RAM when it’s turned off.

The best way to find the right CMOS battery or coin cell battery is to know your computer’s exact make and model. You can find that information on the purchase invoice, underside cover, or in the battery compartment. Once you know your computer’s model #, you can search our database for the correct replacement battery.

If you cannot find the model number of your laptop, or if you suspect you have a bad CMOS battery, you can try to locate the CMOS battery and use our Easy CMOS Battery Builder to configure a matching battery. Most computer makers provide easy access to CMOS batteries so they can be replaced. To use our Easy CMOS Battery Builder tool, you will need to know 4 things: connector type, polarity, length of leads, and battery type.

• Step 1 – Connector Type – You can visually compare the connector to our 3D model in our battery builder. If you are not sure, please send us a picture and we’ll tell you the matching connector number.
• Step 2 – Polarity – Most batteries have two or three wires of different colors. The red one is positive (+) and the black one is negative (-). There can also be a white wire which is the same as black one (-). With the pins facing you, take a note which one is on the left and choose the same polarity in the battery builder.
• Step 3 – Cable Length – Length varies between each computer model. Our batteries come in four different sizes: Short, Medium, Long, and Extra Long. We can also manufacture custom lengths depending on customer requirements. Pick the size which most closely matches your measurement.
• Step 4 – Battery Type – Computer makers use CR2032, CR2025, CR2016, CR1220, ML1220, CR1632, CR1616, and custom Ni-MH batteries. CR2032 and CR2025 are the most common types and custom Ni-MH are a very rare find. Most batteries are 3V with some Ni-MH batteries ranging from 2.4v to 7.2v.

Using these specifications, you can build an identical match to your original battery. If you are unsure about any of the four steps above, please contact us! And remember, if you need to replace the CMOS battery, it’s always a good idea to consult your motherboard documentation first.

If you’re looking for a new battery, whether it’s a coin cell or a rechargeable battery, we’ve got you covered. We’re here to help you find the right battery for your needs.

Using these specifications, you can build an identical match to your original battery. If you are unsure about any of the four steps above, please contact us!

HOW TO CHOOSE THE RIGHT CMOS BATTERY?

A CMOS battery, also known as a ‘clock battery’ provides the main power source for the motherboard of your computer. It is called CMOS battery because it stores settings in CMOS so you see the correct time when the computer takes its settings from system memory. Without a functioning CMOS battery , your computer will not boot up or keep proper time.

How long does a CMOS battery last?

A typical battery life is between 5 and 10 years, but it depends on factors like temperature, discharge rate and usage. Manufacturers usually specify how long the CMOS battery should remain in the computer depending on the coin cell used inside. For example, manufacturers of the CR2032 state that this battery should last up to 6 years as a CMOS battery.

How do I choose the correct CMOS battery?

Computer manufacturers provide information about replacement batteries in the following places:

1. On the battery itself: Look for a battery part number or an FRU printed as well as the type of battery. For example, the battery pictured below has an FRU part number 04X0443 and it is a CR2016 battery.
2. In the user manual: If replacement battery is not listed anywhere else, you can check if there’s information about CMOS batteries or a PDF manual.
3. Contact support: Manufacturer’s support will be able to tell you the part # of the CMOS battery from their internal database.
4. Contact RomeTechBatteries.com support: CMOS batteries can be cross-compatible between multiple computers and we maintain a comprehensive up to date database.

What if I can’t find any information?

A CMOS battery has five components: connector, polarity, leads, length and battery type.

Connector: Computer manufacturers use different types of connectors depending on the motherboard design and specifications. Connectors are not cross-compatible  with each other and oftentimes look very similar. Some connectors have two pins and some have three.

Polarity: All CMOS batteries have a positive or negative polarity. If the + (red) and – (black or white) signs are not lined up properly on the connector, the battery will not work. Most of the time, you can tell which is positive and negative just by looking at the color.

Leads: CMOS batteries typically have two or three leads coming from the coin cell battery to the connector. Some batteries have three pins, but only two leads.

Length: Leads can be short, medium, long or extra long. It’s best to measure the leads in centimeters (cm) and get a replacement that is the same or a little longer. You can always tuck away extra few centimeters near the battery slot.

Battery type: Most newer computers have a lithium-ion CR2032 coin cell battery, but some older computers have a Ni-MH or Ni-Cd battery which is harder to find.

Battery size: There are several choices of coin cell batteries based on the physical aspect, such as diameter and thickness of the battery . These dimensions can also be found from your motherboard documentation or locate it on the battery itself. If the battery is wrapped in PVC film, you can carefully peel away the film and see the type of battery underneath. PVC film is used to shield batteries and prevent electrical interference.

With all of this information, you can build your own battery by using an Easy CMOS Battery Builder located here.

How to build your own CMOS battery?

1. In Step 1: Start by matching your connector to one of the available connectors in the builder. In this step, we are only choosing a connector and ignoring polarity or number of leads.
2. In Step 2: Choose the polarity. Align your computer’s CMOS battery in the same exact way and match up the + (red) and – (black or white) colored leads.
3. In Step 3: Choose the length of the leads that is the same or longer than the original OEM CMOS battery.
4. In Step 4: Choose the battery type. Battery type must be an exact match. All of the lithium-ion coin cell batteries have a 3V output, but vary in size and thickness.

What if my battery type is not available?

Contact RomeTechBatteries.com and get your custom battery manufactured. There is no surcharge for custom batteries, but manufacturing time can be about 30 days.

In conclusion,  be sure to choose an exact replacement battery for your motherboard. If you are unsure about what type of CMOS battery is used or have any other questions, contact RomeTechBatteries.com and we will be happy to help you with your custom made battery needs.

ROME TECH BATTERIES IS COMMITTED TO SUSTAINABILITY

t Rome Tech Batteries, we are proud to be a part of the movement towards a sustainable future. As you may already know, replacing your CMOS battery can have a significant impact on the lifespan of your laptop and the environment. By taking this simple step, you are helping to reduce E-Waste and conserve precious resources.

By reducing E-Waste, we can conserve resources and reduce our impact on the planet. That’s why Rome Tech Batteries is committed to helping ensure that every portable device gets a second chance through our CMOS battery replacements.

When you choose to replace your CMOS battery with one of our products, you are not only extending the lifespan of your laptop, but also supporting environmental sustainability. By reducing waste, reusing products, and recycling resources, we are working towards a better future for generations to come.

Thank you for choosing Rome Tech Batteries, and for being a part of our mission to protect the planet and promote sustainability.

Sincerely,
The Rome Tech Batteries Team
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