About this replacement
Toshiba Dynabook TX / Tecra A9 — 10.8V Li-ion Replacement Battery (PA3356U-1BRS)
This is a 10.8V, 6600mAh (71.28Wh) Li-ion replacement battery for the Toshiba Dynabook TX notebook. It also fits a wide range of Toshiba Satellite and Tecra models sharing the same battery bay and connector, including the Satellite U205-S5034, Tecra A9, and Tecra S3-120. The OEM part number PA3356U-1BRS is the primary reference; cross-references include PABAS048, PA3357U-1BRL, PA3509U-1BRM, and PA3588U-1BRS, among others.
- Dynabook TX and Tecra shared battery platform: These models use the same 10.8V three-cell-series architecture, identical physical bay dimensions (206.90 × 68.90 × 20.50mm), and the same BMS connector pinout. That is why one cell covers all of them — the voltage rail and handshake protocol match across the range.
- Bench tested on actual hardware: We ran this cell through full charge-discharge cycles on Dynabook TX and Tecra A9 units. The BMS accepted the cell without fault codes, balanced across all groups, and reported correct Wh figures in system information after a calibration cycle.
- First-install discharge cycle on Toshiba BIOS: After fitting this cell, run the laptop on battery only until it hibernates at low-charge cutoff. Then charge uninterrupted to 100%. Toshiba's BIOS battery learn cycle requires this to clear the inaccurate health warning that appears after every cell swap — skipping it leaves the fuel gauge reading stale EEPROM data from the old pack.
BIOS reporting poor battery health immediately after fitting a new cell
Toshiba's BIOS reads health data from EEPROM embedded in the battery pack. When a new cell is installed, that EEPROM contains factory default values that do not match the laptop's usage history, so the BIOS flags it as degraded or unknown. This is not a fault with the replacement cell. Run one complete discharge-to-hibernate cycle followed by a full uninterrupted charge — the BIOS learn cycle writes new baseline data to the EEPROM and clears the warning. After two to three full cycles, the health indicator stabilises at the correct value.
Laptop shuts down abruptly at 15–25% charge shown on screen
This happens when the cell voltage drops below the BMS cutoff threshold under full load — CPU at peak draw plus backlit display — before the fuel gauge reaches 0%. The fuel gauge IC calibrates against measured cell voltage over time, and if the calibration cycles have not completed, it misjudges the remaining capacity. The cell hits the voltage cliff and the BMS cuts output before the OS-level low-battery warning fires. Fix this by completing three full discharge-to-hibernate and charge-to-100% cycles so the fuel gauge IC can map the actual voltage curve of the new cell — after that, shutdowns at partial charge should stop.