About this replacement
Toshiba Dynabook Qosmio GXW/70LW — 10.8V Li-ion Replacement Battery (PA3729U-1BAS)
This is a 10.8V, 8800mAh (95.04Wh) Li-ion replacement battery for the Toshiba Dynabook Qosmio GXW/70LW and related Qosmio notebook models. It replaces OEM part numbers PA3729U-1BAS, PA3729U-1BRS, PA3730U-1BAS, PA3730U-1BRS, and PABAS207. The Qosmio line draws significant power from its display and GPU subsystem, so cell capacity here matters more than on lighter notebooks.
- Qosmio GXW, 90LW, 97K, 97L series compatibility: These models share the same battery bay geometry, connector pinout, and BMS handshake protocol. The PA3729/PA3730 part numbers are interchangeable across this platform because Toshiba used the same charging circuit and communication lines throughout the Qosmio generation.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on Qosmio-platform hardware. The BMS communicated correctly with the system controller, charge termination triggered at 100%, and the protection circuit responded normally to load spikes from the GPU and display backlight.
- Post-install discharge cycle on Qosmio: After fitting this battery, run the notebook on battery power until it hibernates at the low-charge cutoff, then charge uninterrupted to 100%. The Qosmio BIOS uses a battery learn cycle to calibrate its fuel gauge IC — skipping this step leaves the system reporting inaccurate health warnings and erratic charge percentages.
Why the Qosmio BIOS flags a new battery as poor health immediately after install
The Qosmio firmware reads EEPROM data stored on the battery's BMS chip. A new cell ships with factory EEPROM values that do not match the learned cycle history the BIOS expects from the original unit. Until the learn cycle runs, the system reports "poor health" or a low Wh figure — not because the cell is faulty, but because the BIOS has not yet calibrated against the new cell's actual charge curve. One full discharge-to-hibernate then full charge clears this. After two to three cycles, the reported health figure stabilises.
Qosmio shutting down at 20–30% charge shown on screen
This happens when the cell voltage drops below the system's minimum threshold under full CPU and display load, even though the fuel gauge still shows charge remaining. The original calibration data no longer matches the new cell, so the OS gauge and the actual cell voltage diverge. Under sustained load — particularly when the GPU and backlight are both running — voltage sags faster than the gauge expects, triggering an immediate shutdown. Discharge fully to hibernate cutoff, charge to 100% uninterrupted, and repeat once more — after two calibration cycles the shutdown threshold and displayed percentage will align.