Battery BIOS (or CMOS battery) is a small but critical element of the laptop, on which the safety of system settings depends when the power is turned off. When it runs low, users experience timing errors, BIOS resets, and even problems loading the OS. In this article we will look at how to determine the malfunction and where to look for the battery in popular laptop models (ASUS, Lenovo, HP, Acer), and how to replace it without the risk of damaging the device.

Many people mistakenly think that BIOS battery lasts forever - in fact, its average service life is 3–7 years (depending on the laptop model and intensity of use). Moreover, in modern ultrabooks with low-profile cases, access to it is often complicated, which requires care when replacing. Next is a detailed guide with photos, tips for choosing a new battery and answers to frequently asked questions.

What is a BIOS battery and why is it needed?

Battery CMOS (Complementary Metal-Oxide-Semiconductor) - this is the power supply for the microcircuit RTC (Real-Time Clock) and memory NVRAM, where BIOS/UEFI settings are stored. Without it, when disconnecting the laptop from the network:

  • 🕒 Time and date are reset - Windows or Linux shows January 1, 2010 or other BIOS release date.
  • ⚙️ BIOS settings are lost — boot priority, hard drive operating modes, cooling parameters.
  • 🔌 Errors occur during startup - for example, message CMOS checksum error or Press F1 to continue.
  • 🖥️ The laptop may not turn on — in rare cases, a low battery blocks the initialization of hardware components.

Most laptops use a lithium battery type CR2032 (3 Volts), less often - CR2026 or CR2016. In compact devices (for example, MacBook Air or Dell XPS 13) the battery may be soldered in, which is more difficult to replace.

⚠️ Attention: Some models Lenovo ThinkPad And HP EliteBook The CMOS battery is soldered to the motherboard. Trying to replace it without a soldering iron and experience can lead to damage to the tracks.

Signs of a Low BIOS Battery

How can you tell if the problem is with the battery and not with a virus, Windows crash, or hard drive failure? Pay attention to the following symptoms:

Symptom Probable Cause Additional checks
Time/date resets after shutdown Battery is 90% discharged Check the BIOS setting Load Default Settings
An error appears CMOS battery failure The battery is completely dead or the contacts have oxidized Inspect the battery for corrosion
The laptop asks to press F1/F2 to continue downloading Boot settings are lost (Boot Order) Go to BIOS and check device priority
BIOS changes are not saved Battery does not supply power to NVRAM Try resetting the BIOS using a jumper (if available)
The laptop turns on every once in a while Unstable CMOS power or motherboard problems Check the power supply and cables

If you observe at least 2-3 signs from the table, the probability of a battery problem is 95%. However, before replacing, it is worth ruling out other reasons:

  • 🔌 Check the power supply — perhaps the laptop is not receiving enough energy.
  • 🦠 Scan your system for viruses — some malware messes up the time.
  • 🔄 Update BIOS - in rare cases, errors are related to the firmware.
📊 How often do you encounter BIOS problems?
  • Never
  • Once every 2-3 years
  • Every year
  • I don't know what BIOS is

Where is the BIOS battery located in a laptop?

The location of the battery depends on the laptop model. In most cases it is hidden under the back cover, but in some devices (for example, MacBook Pro or Microsoft Surface) access to it is difficult. Let's look at typical options:

1. Classic laptops (ASUS, Acer, Lenovo IdeaPad, HP Pavilion)

The battery is located on the motherboard under a removable cover. To get to it:

  1. Turn off the laptop and disconnect the power supply.
  2. Turn the device over and remove the back cover screws (usually marked with 🔧).
  3. Carefully pry the cover with a plastic card - it is held on by latches.
  4. Battery CR2032 will be in a round socket with a metal retainer.

2. Ultrabooks and business models (Dell XPS, Lenovo ThinkPad, HP EliteBook)

In thin laptops, the battery can be:

  • 🔋 Under the keyboard - you need to remove the top panel (risk of damaging the cables!).
  • 🔌 Soldered to the board - in this case, you need the help of a service center.
  • 📦 In a special compartment - for example, in ThinkPad T480 it is hidden under a small cover with the inscription CRU.

3. Apple MacBook (all models)

B MacBook The CMOS battery is soldered into the motherboard. Self-replacement not recommended - required:

  • 🔧 Special tool (P5 Pentalobe for unscrewing screws).
  • 🔥 Soldering station (for models 2015 and newer).
  • 📋 Knowledge of the power supply circuit (risk of short circuit).
⚠️ Attention: In laptops Lenovo Yoga And HP Spectre the battery may be hidden under the battery. Before disassembly be sure to disconnect the main battery - otherwise you risk shorting the board!
What does the BIOS battery look like?

Typically this is a round lithium “pellet” with a diameter of 20 mm (CR2032) with the inscription “3V” and a positive contact on top. Some laptops use a battery with wires (for example, servers or older IBM models).

How to replace the BIOS battery yourself

If you determine that the battery is dead and it is not soldered into the board, you can replace it yourself. You will need:

  • 🔧 Phillips screwdriver (usually PH0 or PH1).
  • 🧲 Plastic spatula or mediator for opening the lid.
  • 🔋 New battery CR2032 (cost: 50–200 rubles).
  • 📸 Phone for photographing the location of the loops.

Step by step instructions:

☑️ Preparing to replace the BIOS battery

Done: 0 / 5

  1. Turn off the power. Unplug the power supply from the outlet and hold down the power button for 10 seconds - this will discharge the residual current in the capacitors.

  2. Remove the back cover. The screws may be different lengths - fold them separately to avoid confusion. Some laptops (eg. ASUS ROG) the cover is secured with latches—pry it up carefully, starting from the corner.

  3. Find the battery. It looks like a shiny round "coin" with the inscription CR2032. In models Dell Latitude can be covered with a black plastic holder.

  4. Remove the old battery. Carefully bend the metal clip to the side (do not break it!) and remove the battery. If it gets stuck, pry it off with a plastic spatula.

  5. Install a new battery. Put it in the nest plus up (there is a marking on the battery +). Secure with a clamp.

  6. Assemble your laptop. Make sure all cables are connected and screw on the cap. Turn on your laptop and check your BIOS settings.

After replacement:

  • ⏰ Set the time and date in BIOS and Windows.
  • ⚙️ Restore boot priority (if you got lost).
  • 🔄 Reset BIOS settings to default (Load Optimized Defaults).
💡

If the laptop does not turn on after replacing the battery, check whether the battery is connected correctly (if you disconnected it). Sometimes holding down the power button for 30 seconds to clear the static charge helps.

Which BIOS battery to choose for replacement

Most laptops use a standard battery CR2032, but there are exceptions. The table below shows compatibility for popular models:

Laptop model Battery type Features
ASUS ZenBook, ROG CR2032 In models ROG Zephyrus battery under the radiator - removal of the cooling system is required.
Lenovo ThinkPad (T/X/P series) CR2032 or soldered B ThinkPad P50 and newer the battery is often soldered.
HP Pavilion, Omen CR2032 B Omen 15 battery under a metal screen.
Dell Inspiron, XPS CR2032 or CR2026 B XPS 13/15 Keyboard removal required.
Acer Swift, Predator CR2032 B Predator Helios battery next to the M.2 slot.

When purchasing a new battery, pay attention to:

  • 🏷️ Marking - must match the old one (for example, CR2032 3V).
  • 🕒 Expiration date — lithium batteries lose their charge even in the packaging.
  • 🛡️ Quality of contacts - Cheap batteries can oxidize faster.

Where to buy:

  • 🛒 Electronics stores (Citylink, M.Video, DNS).
  • 🌍 Online platforms (AliExpress, Wildberries, Ozon).
  • 🔧 Service centers - sometimes they sell original batteries for specific models.
⚠️ Attention: Do not buy batteries with the inscription LR2032 - these are alkaline analogs that are not suitable for CMOS (they will discharge in a few months). Exactly what you need lithium battery!

Common mistakes when replacing the BIOS battery

Even a simple battery replacement can cause problems if you make one of these mistakes:

  1. Using the wrong battery. For example, setting CR2026 instead of CR2032 will lead to unstable operation (different capacities).

  2. Wrong polarity. If you confuse + And –, the battery will not work and in rare cases may damage the RTC chip.

  3. Forgot to reset the BIOS. After replacing the battery, the settings may conflict - be sure to Load Default Settings.

  4. The cables or contacts are damaged. In thin laptops (for example, MacBook Air) the cables are very fragile - they can be easily torn with a screwdriver.

  5. The battery was not disconnected. On some models (Lenovo Legion) the main battery interferes with access to the CMOS battery - it must be disconnected.

If after replacing the laptop:

  • 🔄 Doesn't turn on — check the connections of the battery and power supply.
  • ⏳ Stuck on logo — reset the BIOS using a jumper (if available) or remove the battery for 5 minutes.
  • ⚠️ Shows error Secure Boot violation - disable Secure Boot in BIOS settings.
💡

If problems persist after replacing the battery, the cause may be a faulty RTC chip or damaged tracks on the motherboard. In this case, diagnostics are required at a service center.

Alternative ways to reset the BIOS without replacing the battery

If you don't have a new battery on hand, but need to reset the BIOS settings (for example, after an unsuccessful overclock or crash), you can use one of these methods:

1. Reset by jumper (Clear CMOS Jumper)

Many laptop motherboards have dedicated BIOS reset pins. They can be signed as:

  • CLR_CMOS
  • JCMOS
  • BIOS_RESET

To reset settings:

  1. Turn off the laptop and disconnect the power.
  2. Find the jumper (usually 3 contacts, two of which are shorted with a jumper).
  3. Move the jumper to other pins (e.g. 1-2 on 2-3).
  4. Wait 10-15 seconds and return the jumper to its original position.

2. Reset button on the motherboard

Some laptops (eg. MSI GS65 or ASUS TUF) there is a BIOS reset button. It could be:

  • 🔘 Separate small button next to the battery.
  • 🔄 Key combination (for example, Win + Power in some Lenovo).

3. Soft reset via BIOS

If the laptop turns on, but the settings are lost, try:

  1. Enter the BIOS (usually the F2, Del or Esc when turned on).
  2. Find option Load Optimized Defaults or Reset to Default.
  3. Save changes (F10) and reboot.
⚠️ Attention: Resetting the BIOS will return all settings to factory settings, including boot priority and security settings. If you have it enabled BitLocker (Windows) or FileVault (macOS), after resetting you may need a recovery key!

FAQ: Answers to frequently asked questions

Is it possible to use a battery from a PC motherboard in a laptop?

Yes, if it's the same model (CR2032). CMOS batteries are universal for PCs and laptops, the main thing is that the voltage (3V) and size match. However, some laptops use batteries with cables (such as servers) that will not work.

What happens if you don't change the BIOS battery?

The laptop will work, but:

  • Each time you turn it on you will have to set the time and date.
  • The boot settings may be confused (for example, the laptop will not see the SSD).
  • In rare cases, errors may occur when updating the BIOS.

There will be no critical breakdowns, but the device will become inconvenient to use.

How to check BIOS battery voltage?

Use a multimeter:

  1. Set the DC voltage measurement mode to 20V.
  2. Touch the probes to the battery contacts (+ And –).
  3. Normal voltage - 2.8–3.3V. If it is less than 2.5V, it’s time to change the battery.
Is it possible to charge the BIOS battery?

No. Lithium batteries CR2032 not intended for recharging. Attempts to “reanimate” them using chargers can lead to fire or explosion.

How much does it cost to replace a BIOS battery at a service center?

Prices vary:

  • 🔧 Self-replacement — 50–200 rubles (cost of battery).
  • 🛠️ Service center — 500–2000 rubles (depending on the laptop model).
  • 🔥 Replacing a soldered-in battery — 2000–5000 rubles (soldering station required).