About this replacement
Toshiba Netbook NB100 Series — 7.2V Li-ion Replacement Battery (PA3689U-1BRS)
This is a 7.2V, 4400mAh Li-ion replacement battery for the Toshiba Netbook NB100 range. It fits the NB100, NB100-01G, NB100-111, NB100-12A, and over 34 additional NB100 variants. Replaces OEM part numbers PA3689U-1BAS, PABAS155, PA3689U-1BRS, and PABAS156.
- NB100 series compatibility: All NB100 variants share the same 7.2V two-cell Li-ion architecture, identical connector pinout, and the same BMS handshake protocol. A single cell swap covers the full model range without modification.
- Bench tested on actual hardware: We cycled this cell on an NB100 chassis under combined CPU and display load. The BMS held charge termination correctly at 8.4V and triggered low-voltage cutoff cleanly without dropping into an unrecoverable drain state.
- First-cycle recalibration on the NB100: After installing, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning the NB100 displays after every cell swap.
Why the NB100 BIOS flags a new battery as poor health immediately after swap
The NB100 BIOS reads health data from the battery's EEPROM on first contact. A new cell ships with factory EEPROM values that don't match the old cell's learned cycle history, so the BIOS interprets the mismatch as degraded health. This is a data conflict, not a cell fault. Running the battery learn cycle — one full discharge to hibernate, one uninterrupted charge to 100% — overwrites the stale EEPROM reference. After two to three cycles, the BIOS health indicator normalises.
NB100 shutting down abruptly at 20–30% charge shown
This happens when the fuel gauge IC hasn't calibrated against the new cell's actual voltage curve. The IC still references the old cell's discharge profile, so it misreads remaining capacity and the system shuts down well before the gauge reaches zero. The fix is calibration: discharge the NB100 fully to automatic hibernate cutoff, then charge to 100% without interruption — repeat this two to three times. After calibration, the gauge tracks accurately and the early shutdowns stop.