CR2032 coin cell battery
(Last Updated On: September 26, 2019)

Hey Folks, Did you ever wondered why the system (Desktop/Laptop) time will not change, even though the battery removed. if yes, this article for you you only. In this article, I will clearly explain what is CR2032, why laptop time will not change even though the battery removed.


Since my college days, I have a doubt. If we remove the battery from our mobiles the time will be set to default, after booting up the mobile software it will ask us to set up the current date and time. but in the case of Laptop, it is not happening. If we remove the battery and turn on the laptop it will boot up normally & will not ask for any date or time reset. it will show the exact date and time. I wonder how it is happening. Later I thought my laptop is getting connected to the internet, so it is directly taking date and time from the internet itself. then I removed my laptop internet connection(LAN Cable and WiFi everything) and repeated the same process, but still, the time is the same and there is no change in date aswell. It means there is a timer in my laptop and it is still getting powered even though the battery removed.

Then I started thinking again and searched a lot on google, but I don’t get sufficient information to convince my self.

Now, I just wanted to know why it is happening at any cost. then I took my laptop and opened all the screws and reached to the motherboard.

It is looking something like this.

Hp Laptop mother board

Now I started finding what I want, in this process, I am able to identify my laptop processor, Graphic card, RAM, ROM, power supply unit, wireless communication(Bluetooth/WiFi) module, USB bus. Laptop cooling fan everything.

Then I found a CMOS coin-cell (CR2032) battery which is near to the USB bus and left speaker. My assumption is right the Realtime Clock is getting powered from this small tiny battery. Even if the primary battery disconnected from the PC/Laptop still the CMOS battery is supplying the power to make the RTC active. when the PC restarted again by connecting the AC power supply or a battery CPU will take the time from the RTC which is kept on active. thus the time will not change.

CR2032 coin cell battery

What is RTC???

A real-time clock (RTC) is a battery-powered clock that is included in a microchip in a computer motherboard. This microchip is usually separate from the microprocessor and other chips and is often referred to simply as “the CMOS” (complementary metal-oxide-semiconductor). A small memory on this microchip stores system description or setup values – including current time values stored by the real-time clock. The time values are for the year, month, date, hours, minutes, and seconds. When the computer is turned on, the Basic Input-Output Operating System (BIOS) that is stored in the computer’s read-only memory (ROM) microchip reads the current time from the memory in the chip with the real-time clock.

What is the CMOS (CR2032) Battery:

CR2032 is a high-energy, coin-cell primary lithium battery. The is a premium 3-volt lithium battery is used in remote controls to open cars, autos and every kind of vehicle. It is used by Turnpike Authorities for their consumer transponders. Mercedes uses these in their remote car openers. The Bose Wave Music System. This 3V lithium battery lasts longer than silver-oxide batteries and is great for use in watches, medical devices, and other electronics. Suitable replacements for brands like Duracell®, Eveready and Panasonic®. is a 3V lithium battery and is non-rechargeable.

The name defines the size of the battery like for CR2032, the first two digits stand for diameter and second for height or thickness in tenths of mm. So, according to this 20mm is the diameter of CR2032 and 3.2mm is the thickness.

  • High voltage (3V)
  • Very low self-discharge; long shelf life: up to 10 years
  • A full line up for use in a wide variety of applications
  • No mercury added
  • High leak protection
  • Useful in a wide range of temperatures (-30°C to +60°C)
  • The very high weight-to-power ratio

For more specifications, you can refer the following datasheet: CR2032 datasheet

Long shelf life

90% of the original capacity: that is what lithium coin CR2032 batteries still have after even 10 years. The combination of lithium and manganese dioxide results in a chemically very stable battery. Long-term discharge has been verified at all operating temperatures under low-load discharge conditions.

Ultra-compact power

The lithium coin CR2032 battery has a high voltage of 3V. In short: lots of power in an ultra-compact design. You have enough with one lithium battery in comparison to 2, 3 or more traditional batteries. Choose the lithium coin CR2032 battery as a powerful source of energy for your small devices.

High reliability and safety

Repeated tests on the various safety and performance characteristics of this battery have been conducted. Also, the effects of environmental factors such as temperature were tested. The result is that CR2032 batteries have won consent for their high reliability and safety under the UL safety standards in the United States and wide recognition over the world.


Lithium Coin CR2032 has certain achievements for devices where traditional batteries cannot be used. This battery can be used for memory back-up(RTC), digital watches, car keys, laser pens, fitness appliances and medical devices such as tensiometers and clinical thermometers.

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