Samsung Notebook 9 13.3" Replacement Battery AA-PBUN2LT 7.6V 3900mAh

Samsung Notebook 9 13.3" — 7.6V Li-Polymer Replacement Battery (AA-PBUN2LT)

This is a 7.6V, 3900mAh (29.64Wh) Li-Polymer replacement battery for the Samsung Notebook 9 13.3-inch ultrabook. It fits the NP900X3L series, including NP900X3L-U03 and NP900X3L-U03HK variants. It replaces OEM part AA-PBUN2LT directly.

• NP900X3L series fit: All NP900X3L variants share the same slim Li-Polymer cell format, 7.6V two-cell architecture, and SMBus connector pinout. The BMS communicates over that same bus across the entire model line, so one cell fits every unit in the series.
• Bench tested on actual hardware: We ran this cell in an NP900X3L and confirmed the BMS handshake initialised correctly, charge cycles completed without interruption, and the fuel gauge IC began tracking state-of-charge from the first cycle.
• First-cycle calibration on the NP900X3L: After fitting this cell, run one full discharge until the laptop hibernates on its own, then charge uninterrupted to 100%. This forces the NP900X3L's BIOS battery learn cycle to reset against the new cell's actual capacity and clears the false health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after swap on the NP900X3L

Samsung's battery health indicator on the NP900X3L reads EEPROM data written by the original cell over its charge history. A fresh cell arrives with no cycle data, so the BIOS flags it as degraded before it has ever been used. This is not a fault with the replacement cell — it is a data mismatch. Running one full discharge-to-hibernate followed by a full uninterrupted charge resets the learn cycle and rewrites that EEPROM record. After two to three full cycles the health indicator will display correctly.

Notebook 9 shutting down at 20–30% shown on the fuel gauge

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The gauge is still mapping state-of-charge using the old cell's discharge profile, so it reads 20–30% at a voltage point that is actually close to cutoff. Under combined CPU and display load, that remaining voltage drops sharply and the laptop shuts down before the gauge reaches zero. Run two full discharge-to-hibernate and charge-to-100% cycles without interruption. By the third cycle the fuel gauge IC will track the new cell's curve accurately and the early shutdowns will stop.