About this replacement
Toshiba Netbook NB100 Series — 7.2V Li-ion Replacement Battery (PA3689U-1BAS)
This is a 7.2V, 6600mAh (47.52Wh) Li-ion replacement battery for the Toshiba Netbook NB100 series. It cross-references OEM part numbers PA3689U-1BAS, PABAS155, PA3689U-1BRS, and PABAS156. It fits the NB100, NB100-01G, NB100-111, NB100-12A, and over 34 additional NB100 variants.
- NB100 platform fit: All NB100 variants share the same 7.2V two-cell Li-ion architecture, connector pinout, and BMS communication protocol — so one cell works across the full NB100 range without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an NB100 unit. The BMS handshook correctly, charge current tapered normally at 100%, and protection circuitry triggered as expected at low-voltage cutoff.
- First-cycle conditioning on the NB100: After installation, run one full discharge until the laptop hibernates, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after a cell swap.
Why the NB100 BIOS reports poor battery health after a cell swap
The NB100 BIOS reads health data from EEPROM registers on the battery's protection board. When a new cell is installed, those registers still reflect the degraded state of the old cell. The BIOS flags it as poor health before any charge cycle has run. One full discharge-to-hibernate followed by an uninterrupted charge to 100% allows the BIOS learn cycle to rewrite those values against the new cell's actual capacity.
NB100 shutting down at 20–30% charge remaining after battery swap
This is a voltage cliff failure — the fuel gauge IC is still calibrated to the old cell's discharge curve, so it misreads the new cell's state of charge. Under combined CPU and display load, the real cell voltage drops below the protection board cutoff before the OS gauge reaches 0%. Two to three full discharge-to-hibernate cycles recalibrate the fuel gauge IC against the new chemistry. After calibration, the gauge and actual cutoff voltage will align at approximately 6.0V under load.