About this replacement
Toshiba Mini NB301 / NB302 / NB303 / NB304 — 10.8V Li-ion Replacement Battery (PA3782U-1BRS)
This is a 10.8V 4400mAh (47.52Wh) lithium-ion replacement battery for the Toshiba Mini NB301 series netbook. It fits the NB301, NB302, NB303, and NB304, along with over 40 additional Mini series models sharing the same battery bay and connector. OEM part numbers covered include PA3782U-1BRS, PA3784U-1BRS, PA3783U-1BRS, PA3785U-1BRS, PABAS217, PABAS219, and PABAS220.
- NB300 series battery compatibility: The NB301 through NB304 all share the same 10.8V three-cell configuration, identical connector pinout, and a common BMS handshake protocol — which is why a single replacement cell covers the full range without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on NB301 hardware. The BMS negotiated correctly with the EC, charge acceptance reached full capacity, and no cell-mismatch fault codes were logged during the test.
- Post-install calibration on the NB301: After fitting this battery, 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 that appears after every cell swap on these netbooks.
BIOS reporting poor battery health immediately after fitting a new cell
The NB301 BIOS stores accumulated charge cycle data and health metrics in EEPROM on the old battery pack. When a new cell goes in, that EEPROM data is gone and the BIOS flags an unknown or degraded status. This is not a fault with the replacement — it is the system reacting to missing historical data. Running the full calibration cycle described above gives the BIOS enough charge data to re-establish a baseline. After one or two complete cycles, the health status normalises.
NB301 shutting down abruptly at 20–30% charge shown
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The gauge estimates remaining charge based on the old cell's profile, and when real cell voltage drops under combined CPU and display load, it hits the voltage cliff before the gauge catches up. The fix is to let the battery discharge fully to hibernate-cutoff at least twice — do not interrupt by plugging in early. After two complete cycles, the gauge IC recalibrates and the shutdown-at-30% behaviour stops.