About this replacement
Toshiba Satellite L312 / Portege M800 Series — 10.8V Li-ion Replacement Battery (PA3634U-1BAS)
This is a 10.8V, 8800mAh Li-ion battery replacing the original cell in Toshiba Satellite and Portege laptops. It fits the Satellite L312, Portege M800-113, M808, Satellite U400, and over 150 additional Toshiba notebook models sharing this battery platform. Capacity is 95.04Wh — same cell size as the factory original.
- Satellite / Portege shared battery platform: Toshiba used a common 10.8V rail and connector across the L300, L310, L312, U400, and M800 Portege lines. All share the same BMS handshake protocol and connector pinout, which is why eight OEM part numbers — PA3634U-1BAS through PABAS178 — all cross to this one cell.
- Bench tested on actual hardware: We ran this cell on a Satellite U400 and cycled it through charge, full-load discharge, and BMS cutoff. The protection circuit tripped correctly at low-voltage threshold and accepted a clean recharge from zero without communication errors in the firmware.
- First-cycle recalibration on Toshiba notebooks: After installing, discharge fully until the laptop hibernates on low battery, then charge uninterrupted to 100% without interruption. This forces the BIOS battery learn cycle to reset against the new cell and clears the inaccurate health warning that appears after every cell swap on these Toshiba models.
BIOS reporting battery health as poor immediately after installation
Toshiba's BIOS stores learned capacity data from the old cell in EEPROM. When a new cell goes in, the stored values no longer match actual cell behaviour, so the system flags the battery as degraded or unknown — even though the cell is brand new. This is a calibration mismatch, not a fault. Run one full discharge-to-hibernate cycle followed by a full uninterrupted charge to 100%. The BIOS learn cycle writes new baseline values and the health warning clears.
Laptop shuts down abruptly at 20–30% charge shown on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The OS reads a fuel gauge estimate that drifts high — so the displayed percentage is ahead of the real state of charge. Under combined CPU and display load, voltage drops faster than the stale estimate predicts, and the BMS cuts power before the OS can issue a shutdown warning. Two to three full discharge-recharge cycles bring the fuel gauge IC into sync with the new cell. After calibration, shutdown should not occur above 5–8% remaining.