About this replacement
Toshiba Dynabook Qosmio T750 Series — 10.8V Li-ion Replacement Battery (PA3757U-1BRS)
This is a 10.8V, 4400mAh (47.52Wh) Li-ion battery for the Toshiba Dynabook Qosmio T750 series notebook. It replaces OEM part numbers PA3757U-1BRS and PABAS213. Fits the T750, T750/T8A, T750/T8B, T750/T8BD, and over 54 additional Qosmio T750 variants.
- Qosmio T750 series compatibility: All T750 variants share the same 10.8V three-cell-pair architecture, identical connector pinout, and the same BMS handshake protocol — which is why a single PA3757U-1BRS cell fits the full range without modification.
- Bench tested on actual hardware: We ran this cell on a Qosmio T750 unit under combined CPU and display load. The BMS held the discharge curve steady through full draw, with no mid-cycle voltage drop or protection-circuit trip detected.
- Post-install reset on Qosmio T750: After fitting this cell, run one full discharge down to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
BIOS reporting poor battery health immediately after fitting a new cell
The Qosmio T750 BIOS reads health data stored in the outgoing cell's EEPROM. When you swap cells, the BIOS compares the new cell's EEPROM values against its learned discharge history from the old battery — the mismatch flags as degraded health. This is a firmware calibration issue, not a cell fault. Run one complete discharge-to-hibernate cycle, then a full uninterrupted charge to 100%. The BIOS resets its learn table against the new cell and the warning clears.
Qosmio T750 shutting down abruptly at 20–30% charge shown
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual chemistry. The gauge over-reports remaining charge until the cell hits its voltage cliff under full CPU and display load — then the laptop cuts out without warning. The fix is two or three complete calibration cycles: discharge fully to hibernate-cutoff each time, then charge uninterrupted to 100%. After the third cycle, the fuel gauge IC anchors its curve to the real cell capacity and the early shutdowns stop.