About this replacement
Toshiba Libretto 100 / 110 Series — 10.8V Li-ion Replacement Battery (PA2431)
This is a 10.8V, 3000mAh Li-ion replacement battery for the Toshiba Libretto 100, 100CS, 100CT, and 110 series ultraportable notebook computers. It replaces OEM part numbers PA2431, PA2502, PA2503, and their UR variants. Fit these models and the voltage rail, cell format, and connector all match the original spec.
- Libretto 100 and 110 series compatibility: These models share the same battery bay geometry, 10.8V three-cell series configuration, and connector pinout. The BMS handshake protocol is identical across the 100CS, 100CT, and 110 variants, so one cell works across the full range without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Libretto unit. The BMS negotiated correctly, charge termination triggered at the expected cutoff voltage, and the fuel gauge IC registered the new cell without throwing an error state.
- First-cycle discharge protocol for the Libretto: After installing, run the laptop on battery until it hibernates at low-voltage cutoff — do not interrupt. Then charge uninterrupted to 100%. This single full cycle resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on these older Toshiba units.
BIOS reporting poor battery health immediately after fitting a new cell
The Libretto's BIOS reads health data stored in the battery's EEPROM. When a new cell is installed, that EEPROM contains factory default values that do not match the host system's charge history. The BIOS interprets the mismatch as a degraded or unknown battery and flags it accordingly. Running one complete discharge-to-hibernate then a full uninterrupted charge writes fresh cycle data and resolves the warning on the next boot.
Libretto shutting down suddenly while the OS still shows 20–30% remaining
This is a voltage cliff failure, not a fuel gauge error. Under combined CPU and display load, cell voltage drops faster than the fuel gauge IC can track. The BIOS sees the voltage fall below its cutoff threshold and cuts power immediately — even though the displayed percentage had not reached zero. The fix is a full calibration cycle: discharge completely to hibernate, charge to 100%, and let the fuel gauge IC map the new cell's actual voltage curve. After two full cycles the reported percentage and actual cutoff align.