About this replacement
Toshiba Satellite A80 / M40 / Tecra A3 Series — 10.8V Li-ion Replacement Battery (PA3478U-1BRS)
This is a 10.8V, 4400mAh Li-ion replacement battery for Toshiba Satellite and Tecra laptops. It fits the Satellite A80-116, Satellite M40-300, Tecra A3-181, Satellite M100-ST5111, and over 300 additional models sharing the same connector and BMS protocol. OEM part numbers covered include PA3478U-1BRS, PA3399U-1BRS, PA3400U-1BRS, PABAS076, and PABAS057.
- Satellite and Tecra shared platform: These models run the same 10.8V power rail and use an identical dock connector with the same BMS handshake. One cell pack covers all of them without adapter modifications or firmware differences between models.
- Bench tested on actual hardware: We ran this cell on a Satellite M40-300 and a Tecra A3-181. The BMS authenticated on first boot, charge initiated without manual reset, and the fuel gauge IC tracked the new cell through two full cycles before locking in stable capacity reporting.
- Post-install discharge cycle on Toshiba laptops: After fitting this battery, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. Toshiba's BIOS battery learn cycle depends on this sequence. Skipping it causes the BIOS to hold stale health data from the old cell and flag the new battery as degraded.
BIOS reporting poor battery health immediately after cell swap
Toshiba laptops store battery health data in EEPROM, tied to the previous cell's charge history. When you swap the physical cell, the BIOS does not automatically clear that data — it reads the old EEPROM profile against the new cell and flags a mismatch as poor health. This is not a fault with the replacement battery. To clear it, run one full discharge to hibernate, then a full uninterrupted charge to 100%. After two complete cycles, the BIOS learn cycle overwrites the old EEPROM values and the health warning clears.
Laptop shuts down abruptly at 20–30% charge shown on screen
This happens when the cell voltage drops below the BMS cutoff threshold under combined CPU and display load, even though the OS fuel gauge still reads 20–30%. The fuel gauge IC is reading stored capacity estimates, not live cell voltage — the two diverge when a cell ages or after a swap before calibration completes. Under full load, the voltage cliff arrives faster than the gauge predicts, and the BMS cuts power to protect the cell. Run two full discharge-to-hibernate and full-recharge cycles to give the fuel gauge IC accurate data points against the new cell; after calibration, the shutdown threshold and the displayed percentage will align.