Where Is The BIOS Battery On A Laptop? | Quick Access Guide

Guide / By

The BIOS battery on a laptop sits on the motherboard—usually a coin cell under the bottom cover, sometimes near the keyboard or palm rest.

Lost time and date on every boot? BIOS settings that won’t stick? Those symptoms point to the tiny real-time clock (RTC) battery—often called the CMOS or BIOS battery. Finding it isn’t the same on every notebook, but there’s a reliable process that works across brands. This guide shows where manufacturers usually place it, how to spot each style, and the right way to reach it without damaging cables or voiding service work you still plan to use.

BIOS Battery Location In Laptops: Quick Ways To Find It

Most notebooks hide the RTC cell inside the chassis. Common placements include:

  • Under the bottom cover: Near RAM or the M.2 slot, easy to see once the base is off.
  • Beneath the keyboard or palm rest: Typical on older models; removal requires care with ribbon cables.
  • Wrapped coin cell on a lead: A small coin cell sealed in heat-shrink plastic, plugged into a tiny board header.
  • Rechargeable RTC cell: Thin coin cells (ML1220/ML1225/LIR2032) wired to the board, often taped down.
  • No separate cell on some designs: A number of modern systems keep RTC power from the main pack; clearing settings involves a full power drain routine rather than swapping a coin cell.

Safety And Setup Before You Open Anything

Work on a clean table. Shut down the laptop. Unplug the charger. If your model has an internal main battery, disconnect it as soon as the base is off. Ground yourself by touching a metal surface to reduce static risk. Keep screws sorted by length; mixing them can pierce the board or palm rest during reassembly.

Confirm Your Model And Service Manual

Start with the exact model name (label on the base or in BIOS). Then pull the official service guide. It shows screw count, cable routing, and the RTC part number. For instance, Dell’s step-by-step coin-cell guide explains common removal patterns and cautions about tiny battery headers, which mirrors what you’ll see inside many models. Dell coin-cell replacement instructions give a good baseline even if you own another brand. HP also publishes model-specific RTC procedures; one business-class walkthrough shows placement and cable orientation clearly—handy for visual confirmation. See HP’s guide: remove and replace the RTC battery.

How To Spot The Battery Style Inside Your Notebook

Board-Mounted Coin Cell

A round, silver cell in a plastic holder on the motherboard. Press the latch and lift the cell out. Orientation matters—match the + side on install.

Wrapped Cell With Two-Wire Lead

Common in thin-and-light machines. The coin cell sits inside black or yellow heat-shrink with a two-pin micro-connector. Pry the tape gently, then unplug the connector by the housing—not the wires.

Rechargeable RTC Cell

Thin coin cell with a short cable, often labeled ML1220/ML1225/LIR2032. It’s taped down near the speaker, touchpad well, or SSD bay. Replace like for like; avoid swapping a rechargeable cell with a standard CR series part.

Designs Without A Separate RTC Cell

Some platforms keep RTC with the main battery. To clear stale settings, disconnect the main pack and the charger, then hold the power button 30–60 seconds to bleed residual charge. After reconnecting, enter BIOS and save defaults.

Step-By-Step: Reaching The RTC Area Safely

  1. Power down: Shut down, unplug AC, eject any SD card/USB dongles.
  2. Remove the base: Back out the visible screws. Many covers also use clips; slide a plastic spudger around the seam rather than twisting metal tools.
  3. Disconnect the main battery: If internal, remove its screws and lift the battery or unplug its board connector before touching the RTC lead.
  4. Locate the RTC: Look near the RAM slots, M.2 SSD, speakers, or under light foam tape along the board edge.
  5. Free the cell: For a holder type, press the latch. For a wired pack, peel the tape and unplug the connector with a steady pull on the plug body.
  6. Install the new part: Match voltage/chemistry and connector. Seat the coin cell with the + side up if using a holder.
  7. Reassemble: Reconnect the main battery, set the base in place, and return screws by length. Don’t overtighten.
  8. Reset and test: Power on, enter BIOS, load defaults, set date/time, save and exit. Boot to the OS; then shut down and start again to confirm settings stick.

Brand-By-Brand Clues That Save Time

Dell

Many models place a wrapped coin cell near the left speaker or just below the RAM. You’ll often find a two-pin connector with short leads. The service manual spells out screw map and sequence; Dell’s coin-cell guide linked above mirrors those steps.

HP

Business notebooks usually label the pack as “RTC.” It may sit by the touchpad well or under a thin shield. HP’s service pages show photos and connector angles, which helps avoid yanking a short cable.

Lenovo

ThinkPad lines often stash the RTC near the trackpad or beside the speakers; some generations put it under the keyboard deck. Certain X1 models use very short cables—lift the base slowly and scan for a taped coin cell before pulling.

Acer And Others

Ultrabooks commonly use a wired coin cell taped to the board edge. Gaming laptops are more likely to use a holder near the M.2 or SATA area. If the base is crowded, check under small foam covers.

When Your Laptop Has No Standalone RTC Cell

Not every machine uses a separate coin cell. If you can’t find one, the board may keep CMOS through the main pack. To clear settings on these designs:

  • Disconnect AC and the internal battery.
  • Hold the power button for a full minute.
  • Reconnect, boot to BIOS, load defaults, save, and restart.

Many owners only need this reset to fix boot loops or “time not set” errors after a deep discharge.

Choosing The Right Replacement

Match the part exactly: CR2032 for holder types, the same ML/LIR model for rechargeable styles, and the same two-pin connector for wrapped packs. If the wiring length differs, the lead can tug against the base when reinstalled—never stretch it across fan blades or hinge arms.

Common Symptoms That Point To The RTC Cell

  • Date and time reset on every start.
  • BIOS changes don’t save after shutdown.
  • Boot pauses with prompts to enter setup.
  • Fan spins and lights flash, then power cuts after a few seconds.

Those signs can also come from a depleted main battery or a corrupted BIOS image. Always try a full power drain and a BIOS default load before swapping parts.

Practical Tips From Real-World Tear-Downs

  • Check under small black tape squares: Many builders tape the coin cell to spare board space.
  • Scan edges first: The pack often lives along the board perimeter, away from heat pipes.
  • Mind tiny speakers: RTC leads route near speaker enclosures; don’t pinch them during reassembly.
  • Photograph each step: A quick phone photo of cable paths saves time later.

Simple Troubleshooting Before Replacement

  1. Load BIOS defaults, save, and reboot twice.
  2. Update the BIOS/UEFI from the vendor page for your model.
  3. Run a power drain: remove AC and main battery (or flip the battery disconnect switch if your board has one), hold power 60 seconds, reconnect, and test.

If settings still vanish after an overnight shutdown, the RTC cell is likely done.

Time Budget For Each Access Route

  • Bottom cover only: 10–20 minutes for removal, swap, and test.
  • Keyboard or palm rest removal: 30–45 minutes due to ribbon cables and extra screws.
  • No standalone cell (main-battery RTC): 5–10 minutes for a full power drain and BIOS reset.

What If You Can’t Find The Cell At All?

Search your model’s maintenance manual for “coin-cell,” “RTC,” or “CMOS.” If the PDF lists “RTC reset” steps but no part, you’re likely on a main-battery RTC platform. Community repair guides and teardown photos for your exact model also help confirm placement when the OEM PDF isn’t clear.

Quick Reference: Typical Placement By Brand And Series

The table below summarizes common placement patterns so you can head straight to the likely zone once the cover is off.

Brand / Series Common Placement Access Notes
Dell Latitude / Inspiron Wrapped coin cell near speakers or RAM Two-pin plug; disconnect main pack first
HP ProBook / EliteBook Labeled “RTC” by touchpad well or board edge Taped down; short lead—lift base slowly
Lenovo ThinkPad By speakers or under keyboard deck Very short lead on some X1 units; check tape
Acer Aspire / Nitro Board edge near M.2 or fan shroud Often a holder type; match cell chemistry
Ultrabook Designs Rechargeable ML/LIR cell under tape Do not replace with a CR series coin cell

After The Swap: Settings To Re-Enter

Enter BIOS and set time/date, boot order, and any device toggles you changed before (e.g., virtualization, secure boot state, SATA/AHCI mode on older units). Save, then do two clean restarts. If your clock still drifts or boot pauses return, recheck the connector seating and battery orientation.

When To Call In A Technician

Stop and get help if you see liquid damage, heavy corrosion around the RTC area, or torn ribbon cables. If the laptop is still under service coverage, replacing the RTC yourself can complicate later board repairs. When in doubt, use the OEM service channel and reference the RTC part from the maintenance guide.

Wrap-Up

Finding the tiny RTC cell comes down to a method: confirm the model, pull the right guide, open the base cleanly, disconnect the main pack, and scan the board edges and speaker zones. Whether it’s a holder-mounted CR2032, a taped rechargeable coin cell, or a design that relies on the main pack, the steps above get you to a stable clock and BIOS that saves settings again.