About this replacement
Toshiba Satellite NB300 / NB305 — 10.8V Li-ion Replacement Battery (PA3783U-1BRS)
This is a 10.8V, 4400mAh (47.52Wh) Li-ion replacement battery for the Toshiba Satellite NB300, NB305, NB305-N410BL, and Satellite N302 netbook series. It cross-references OEM part numbers PA3783U-1BRS, PA3785U-1BRS, PABAS218, and PABAS220. If your original Toshiba cell has stopped holding charge or won't register in Windows, this is the direct cell replacement.
- NB300 and NB305 platform fit: Both the NB300 and NB305 share the same battery bay dimensions, connector pinout, and BMS handshake protocol — which is why a single part number covers the full range. Swapping between these models carries no compatibility risk on the hardware side.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the NB305 platform. The BMS communicated correctly with the EC, charge acceptance reached the rated 4400mAh, and the protection circuit triggered cleanly at low-voltage cutoff with no mid-cycle drops.
- First-cycle calibration on the NB300: After installing, run one full discharge down to hibernate cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears on the taskbar after a cell swap.
Why the NB300 BIOS reports poor battery health on a new cell
The Satellite NB300 stores battery health data in EEPROM on the battery controller. When a new cell goes in, the BIOS reads stale or zeroed EEPROM data and flags the battery as degraded or unknown before any cycles have run. This is not a fault with the replacement cell — it is the system's fuel gauge IC reacting to a blank state register. One full discharge-to-hibernate followed by an uninterrupted charge to 100% writes fresh data to the fuel gauge and clears the warning. After two to three full cycles, the health indicator in Windows and Toshiba Power Saver will read accurately.
Satellite NB300 shutting down 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 OS reads 25% remaining, but the cell voltage has already dropped below the EC's shutdown threshold under combined CPU and display load — so the laptop cuts out without warning. The fuel gauge needs at least two full discharge-to-hibernate cycles to remap the voltage-to-capacity curve for the new chemistry. After calibration, the percentage shown at shutdown should be in the 3–5% range at a resting cell voltage of approximately 10.8V under light load.