On most Toshiba laptops, the CMOS battery sits under the bottom cover or a small access panel; some models place it beneath the keyboard.
Why This Matters And What You’ll Learn
The tiny cell that keeps BIOS time and settings alive can bring on date resets, boot errors, and beeps when it fails. Finding it is half the battle. This guide shows typical spots on common Toshiba lines, how to reach them without damage, and smart checks to run before you grab a screwdriver.
Typical CMOS Battery Spots On Toshiba Laptops
Toshiba (now Dynabook) used two main layouts across Satellite, Tecra, and Portégé lines. Many mid-2010s notebooks place a CR2032 coin cell near memory under the lower shell. Some older Satellites include a small hatch with a direct view of the cell. Slim Portégé units hide the cell inside, reachable only after lifting the base panel.
Under A Small Bottom Hatch
Several 15–17-inch Satellites ship with a tiny door in the center of the base. Open the door and the coin cell sits in a holder beside Wi-Fi or RAM. A clear case: the Satellite L775D series, which exposes the holder behind a single screw cover on the underside.
Under The Entire Bottom Cover
Many L-series and S-series notebooks require removing the full base. After the panel comes off, the coin cell sits on the system board near memory slots or the optical bay. An L55-A is a clean example: take off the RAM panel, remove the base, and the CR2032 lifts out of a spring clip.
Below The Keyboard Or On Board Underside
Some designs park the RTC cell on the reverse side of the motherboard. Reaching it means splitting the case and lifting the board after the keyboard and top shell come off. This layout shows up on select Satellite trims and several business units.
Confirm Your Model And Check For A Door First
Flip the unit and read the model label near the vents. Search the exact model number plus “maintenance manual” or “CMOS battery” to see which style you own. Before any deep work, scan the bottom for a small square or rectangular panel secured by one screw. If you see it, you likely have the quick-access type.
Safe Prep Before You Open The Case
Power And Static
Shut the laptop down, unplug AC, and remove the main battery if it’s removable. Hold the power button for 10–15 seconds to drain residual charge. Use a non-metal spudger where you can, and work on a wood or antistatic mat. Ground yourself to avoid zapping the board.
Tools You’ll Need
- Small Phillips screwdriver (#0 or #1)
- Plastic opening pick or spudger
- Tweezers for spring clips and ribbon latches
- Magnetic tray for screws and panels
- Replacement cell: usually CR2032; some thin units use a cabled RTC pack
Step-By-Step: Fast Access Layout
1) Open The Hatch
Remove the single screw on the center panel and lift the door.
2) Pop The Coin Cell
Push the retaining clip aside and lift the battery out. Note the + side orientation.
3) Install The New Cell
Press the replacement into the holder until it clicks. Refit the panel and screw.
Step-By-Step: Full Bottom Cover Layout
1) Remove Bay Panels And Drives
Take off the RAM or storage panels, then slide out any optical drive.
2) Lift The Base Panel
Remove all perimeter screws, then unclip the base with a pick. Work around ports first to keep clips from breaking.
3) Replace The Cell
Locate the coin cell near memory or the optical bay and press it out of its clip. Seat the new one with the + face up. Reassemble in reverse.
Step-By-Step: Keyboard-Side Layout
1) Free The Keyboard
Remove the keyboard screws on the underside (look for tiny keyboard icons), then lift the keyboard and open the ribbon latch.
2) Separate The Top Shell
Undo the palm-rest screws and pry the upper case loose, watching for touchpad and power ribbons.
3) Flip The Board
Disconnect display and speaker cables, lift the motherboard, and locate the coin cell on the reverse. Swap the battery and build the stack back up.
When A Toshiba Uses A Rechargeable RTC Pack
Not every unit uses a loose CR2032. Some thin models ship with a small cabled pack wrapped in heat-shrink. It plugs into a two-pin header on the board. Match the part by connector and voltage. Do not solder a coin cell directly to the board.
Quick Checks Before You Replace Anything
- If you only see a time error once, plug in AC and let the unit stay on to top up a rechargeable RTC pack.
- Update BIOS to the latest revision, since some boot errors clear after a firmware update.
- Run Windows time sync and set the clock after any change.
Model-Specific Clues From Trusted Guides
Public repair guides show where designers put the cell on real machines. A large L775 series exposes the coin cell behind a tiny door on the base. An L55-A shows the cell under the main panel beside the optical drive bay. Business-class Portégé units tend to put the pack under the lower panel near memory.
How To Identify The Cell Type You Need
Open access just far enough to see the part. If you spot a bare coin in a clip, it’s almost always a CR2032. If you see heat-shrink around a round pack with a short lead and a two-pin plug, search the model plus “RTC battery” to match the connector. Measure the diameter if you’re unsure: a CR2032 is 20 mm across and about 3.2 mm thick. Keep the original as a reference until the swap is done.
Match Voltage And Connector
Most coin cells are 3V lithium. Cabled packs are usually two 1.5V button cells in series or a rechargeable pack. If your board label says “RTC BAT CN,” use the same plug type. Mixing parts here can lead to charge faults.
Mind The Holder
Spring clips can lose tension with age. If the cell feels loose, pinch the clip in slightly with tweezers during reassembly so contact is firm.
Data And Settings You May Need Later
Before you pull the cell, shoot quick photos of each BIOS page and note boot mode, boot order, and SATA mode so you can restore them.
Service Info From The Source
If you want to read the official take on the small battery that feeds the clock and BIOS memory, Dynabook’s page on the RTC (CMOS) battery explains what it does and why leaving the laptop on can recharge certain packs. That’s useful when you’re testing whether a pack is simply drained or needs a swap.
Real-World Examples You Can Follow
A Satellite L55-A guide shows the coin cell under the base panel in a simple spring holder—handy if your layout looks the same. You can view that step-by-step walkthrough here: L55-A CMOS battery guide. An L775D write-up shows the quick-access door style on the underside.
Table: Common Toshiba Layouts And Where To Look
| Model Family | Likely Location | Notes |
|---|---|---|
| Satellite L775/L755 | Small access panel on base | Door with one screw; coin cell in clip |
| Satellite L55/L50 | Under full bottom panel | CR2032 near RAM or optical bay |
| Portégé Z-series | Under base; inside chassis | Thin design; may use cabled RTC pack |
After You Swap The Cell
Reset BIOS Defaults
Enter setup on first boot, load setup defaults, then set date, time, and boot order. Save and exit.
Windows Steps
Boot into Windows, confirm the clock is correct, and sync with an Internet time server. Check that sleep, wake, and Wi-Fi work as before.
Troubleshooting Tips If The Error Returns
If a “bad RTC battery” or CMOS checksum message keeps coming back, the cell may be loose or the pack may not match spec. Reseat the battery, check the clip tension, and inspect for corrosion. If the cell is new and errors remain, the charging circuit or holder could be damaged, which calls for board-level repair.
Parts Sourcing And Warranty Notes
New coin cells are inexpensive, and in many models the coin drops in without solder. Cabled RTC packs vary by plug shape and lead length, so match by model number or connector photo. If your device is under warranty or you prefer a bench tech to handle the work, you can book a visit with a Dynabook Authorized Service Provider in your region.
What To Do If Power Issues Remain
A dead main battery or old BIOS can look like an RTC fault. Try an AC-only boot with the main battery removed. Hold the power button for 30–90 seconds to clear static, then try again. Update BIOS from the Dynabook page for your exact model. If the date sticks after that, your RTC swap worked.
Final Word On Finding The Battery
Scan the base for a tiny door first. If there’s none, lift the entire bottom shell. If you still can’t spot the coin, the board-underside layout is likely, which means a deeper strip-down. With the steps in this guide and the linked references, you can pinpoint the cell on nearly any Toshiba-branded notebook and replace it with care.