Useful Tips

What is it for and how to replace the BIOS battery yourself


  • CR2032 (Is standard. Thickness is 3.1 mm)
  • CR2025 (2.4mm Thickness),
  • CR2016 (Thickness 1.6 mm).

In order to find out what kind of battery you have, you need to pull out the old one and see what is written on it.

In extreme cases, you can put another battery instead of one, as they differ only in thickness. In this case, you will have to slightly bend the contact that holds the battery on the motherboard.

Bend this contact to insert a thinner battery

How to replace the battery in the computer?

  1. The first thing to do is turn off the computer and completely turn off its power by unplugging the power cord from the outlet,
  2. Next, unscrew the side cover and visually find the battery,
  3. Using a screwdriver or scissors, gently pry the battery from one side. Some motherboards have a special metal foot that you need to press and the battery will pop out by itself,
  4. We insert a new battery, twist the side cover and turn on the computer,
  5. When you turn it on for the first time after replacing the battery, you will lose all BIOS settings, date and time. Most likely to display this error. You will be prompted to enter the BIOS or apply the default settings. (F1, F2, DELETE).

How to remove the battery from the motherboard

Why do I need a battery on the computer motherboard

The only reason you need a battery on the computer’s motherboard is to power the CMOS memory chip, which contains the BIOS settings, that is, the basic computer configuration settings. In addition, thanks to the independent power, the built-in clock works. That is why they do not go astray when the system unit is disconnected from the network.

Symptoms of a Dead BIOS Battery

When the battery is low, a variety of symptoms appear, sometimes implicit. The simplest symptom is the constant resetting of the system clock. This entails other problems, for example:

  • The browser on different sites swears on outdated security certificates, since the system time can differ by several years, or even tens of years.
  • Anti-Virus can report that its databases are outdated and the license is invalid, and all because of a date mismatch with the current one.
  • Another symptom is that some programs stop starting. Again due to a glitch in the calendar.

Usually, when you turn on the computer, you can detect signs of a dead battery - a message appears after the BIOS test, and further loading of the system may not go. Often this inscription looks like “Press F1 to CMOS Setup”, and when you press the F1 key, you go to the settings. The fact is that they are reset to the default settings, and each time the configuration must be configured, since nothing is saved after shutdown. Although the computer usually starts up with default settings, the history repeats every time it is turned on.

Messages may be different, and all because of the BIOS battery. For example, there is an inscription “CMOS Battery Failed”, which clearly indicates a problem, or “System Battery State Low” - a warning about low battery. If you remove the battery from the motherboard and check the voltage at its contacts, then it really will be noticeably lower than expected.

Where is the battery and how does it look

Finding this item is easy. If you open the system unit, you can immediately see which battery is in the motherboard and where it is located. It is difficult not to notice this shiny round element. It is located in a simple round nest with a clamp, which can be located both horizontally and vertically - on the edge, depending on the design of the motherboard. The BIOS battery is located next to the microcircuit that it feeds, it is easy to find an inscription on it. Nearby there is a jumper to reset the settings. Many people think that this is a battery that is recharged while the computer is running, but in fact it is not. The battery in the motherboard is the most common - manganese dioxide lithium, with a diameter of 20 mm., With a voltage of about 3 volts. The same are used in wall clocks, in electronic scales and in other household appliances.

It is marked, for example, as CR2025 or CR2032. The first number 20 is the diameter in millimeters, and the second is the thickness. The most common - CR2032, most likely, you will find such a battery in your system unit. It lasts for a period of 3-5 years, after which its voltage drops to about 2 volts and problems begin, as this is not enough to power the CMOS chip and requires replacement. Sometimes the batteries last for a longer period - some work for 7 years, and even longer, but sooner or later they drain their life.

How to replace the battery in the computer

Replacing the battery on the computer’s motherboard is a snap. Let's consider it in more detail:

  • Disconnect the computer from the network, including the power switch on the back of the chassis.
  • Wait a few minutes.
  • Remove the system unit cover - left, viewed from the front.
  • Find the battery - it is inserted into a round plastic socket and can be located flat on the board or on the edge.
  • Pull the latch with a screwdriver or tweezers while squeezing the battery to the side. After that take it out.
  • Carefully install a new one, the latch should close.
  • Replace the computer cover in place.

Removing the battery is the most difficult part of this entire procedure, especially if it is located vertically. You need to do everything carefully so as not to tear anything, so it’s convenient to use a small screwdriver or tweezers. After turning on, you need to go into the BIOS and reinstall the clock and date. Typically, you can enter the settings by pressing the Delete or F2 key immediately after switching on. You may need to change settings to increase computer performance or change boot devices. After all, the original ones were discarded when the old battery was still standing.

Now you know how to remove the battery from the motherboard and what it is for. It is very simple to do this, but you need to be careful, because the computer is a rather sensitive and complex device, you can break it with an awkward movement, and even brute force.

When do I need to change the BIOS battery?

Sure signs that soon the battery

finally dies is:

Preliminary signs:

the time on the computer at some point ceases to correspond to real time — more often than not, it starts to lag far behind, run forward, and have to fail once a week or two.

Clear signs:

  • the computer’s date and time are reset (or / and when turned on, an error appears - and to continue loading, the F1 key is pressed each time), the time is reset to 0-00, and the date is usually the BIOS firmware release date,
  • changed and saved BIOS parameters are reset,
  • Errors occur during power-up, i.e. the computer “shut down” at the very beginning of the download - until the operating system started loading, i.e. until the moment when control was given to the bootloader from the hard drive.

Replacing the battery in a regular computer is as easy as shelling pears:

  1. We buy a "battery - tablet for a computer motherboard" in any computer store (usually and preferably in the light of the above, this is a CR2032 battery,)
  2. We take out the system unit, disconnect the cable (if the supply of wires allows it to be completely comfortable to extend the system unit for its full access, then the wires can not be removed)
  3. We place the system unit vertically (less conveniently), or lay it on the right side, if you look at it from the front (more convenient, but not always there is so much space).
  4. Unscrew the cross-shaped reciprocal left side cover (2 screws on the back), remove the cover.
  5. We gently pry the battery with a thin screwdriver and remove the battery from the socket in the opposite direction from the snap-on contact plate (the plate is usually quite flexible, and without problems bends with the removed battery to the required distance in order to remove the battery from the socket)
  6. We take a new battery, and by slightly bending the contact plate, push the new battery into the slot, check that the upper conductive plate presses the battery well.
  7. That's it, we assemble the case, insert the disconnected wires, if you took them out into place.

Replacing the battery in the BIOS (SMOS) on a laptop (netbook)

  1. In laptops, change the battery in the same way, but the main difficulty here comes with disassembling a laptop - but here in most cases the forethought of many (but not all) laptop manufacturers helps. In special easily accessible hatches - the rectangles located below for access to memory blocks and the hard disk (we snap off simple latches - or we unscrew 1-2 self-tapping screws), and we look there for the remote BIOS battery (including on a flexible cable) along the edges of these hatches.
  2. If there is no battery in the hatches, in this case it is better to give the laptop to a specialist, since it is practically impossible to disassemble any laptop without breaking it without practical experience. You just break it, and often it will not be possible even to restore it to an experienced master without serious expenses for spare parts.

After replacing the SMOS battery (BIOS)

At the final stage: turn on the computer, enter the bios, set the date and time, load the “optimized settings”, set your specific settings and options (usually you need to check the boot order - hard drives, video card options) then exit with the save (“F10 "-" Y "). Everything.

Can I change on a computer that is turned on?

You can change the battery on the computer turned on, and in this case the BIOS settings will not fly off - they will not go wrong, but when you pry the battery with a thin metal screwdriver for example, it’s far from the fact that you will not short-circuit something on the motherboard, well, or do not dry the fingers about the fan.
In general, I would not recommend this option if you do not have a certain knack.