About this replacement
Toshiba Satellite NB300 / NB305 — 10.8V Li-ion Replacement Battery (PA3783U-1BRS)
This is a 10.8V, 6600mAh (71.28Wh) Li-ion replacement battery for the Toshiba Satellite NB300 series netbook. It fits the Satellite NB300, NB305, NB305-N410BL, and Satellite N302, among other models in the same family. It replaces OEM part numbers PA3783U-1BRS, PA3785U-1BRS, PABAS218, and PABAS220.
- NB300 / NB305 family fit: These models share the same connector pinout, voltage rail, and BMS handshake protocol across the series. A single cell works across all of them without adapter or modification.
- Bench tested on actual hardware: We cycled this battery through charge and discharge on the NB300 platform. The BMS communicated correctly with the Toshiba firmware — no fault codes, no charge interruptions, and the protection circuit tripped cleanly at low-voltage cutoff as expected.
- First-cycle calibration on the NB300: After installing, run one full discharge until the laptop hibernates on low battery, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears in Toshiba system tools after a cell swap.
Why the NB300 BIOS reports poor battery health immediately after replacement
The Toshiba BIOS stores charge-cycle history and health data in EEPROM on the original cell. When a new cell is installed, that EEPROM data is gone. The BIOS reads the blank or mismatched register and flags the battery as degraded or unknown — even if the new cell is at full capacity. This is a firmware read issue, not a hardware fault. Running one complete discharge-to-hibernate followed by an uninterrupted full charge gives the BIOS a fresh data point and typically clears the warning within two cycles.
NB300 shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC hasn't yet calibrated against the new cell's actual voltage curve. The gauge carries over reference points from the old, degraded cell and calls cutoff too early. Under combined CPU and display load, the laptop hits what looks like 20–30% but is actually near the cell's true low-voltage floor. Two to three full discharge-and-charge cycles recalibrate the fuel gauge IC. After calibration, the percentage shown should align with actual remaining capacity — confirm by watching the voltage hold above 10.8V under load.