Tuxedo Book BM1507 Replacement Battery 14.4V 2200mAh

Tuxedo Book BM1507(N750BU) — 14.4V Li-ion Replacement Battery

This is a 14.4V, 2200mAh (31.68Wh) Li-ion replacement battery for the Tuxedo Book BM1507(N750BU) Linux ultrabook. It fits the N750BU chassis and restores portable operation when the original cell can no longer hold a working charge. No OEM part number is published for this model — fitment is confirmed against the BM1507(N750BU) platform directly.

• BM1507(N750BU) platform fit: The N750BU chassis uses a specific connector orientation and BMS handshake tied to the 14.4V four-cell configuration. Substituting a different voltage rail triggers an immediate BIOS fault. This cell matches the required voltage and cell count so the embedded controller recognises it without a firmware override.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the BM1507(N750BU) platform. The BMS accepted the new cell, protection circuitry engaged correctly at cutoff voltage, and charge current tapered as expected in the final stage. No anomalous cutoffs were recorded under CPU and display load.
• Post-swap calibration on Tuxedo Linux: After installation, run one full discharge until the system hibernates at its low-voltage cutoff, then charge uninterrupted to 100%. This forces the fuel gauge IC to re-learn the new cell's capacity curve and clears the inaccurate battery health warning the BIOS generates after every cell replacement.

Why the BM1507(N750BU) reports poor battery health immediately after a cell swap

The BIOS reads health data from EEPROM registers that were written against the old cell's cycle count and capacity history. A brand-new cell carries different EEPROM values, so the embedded controller flags it as degraded before any real measurement occurs. This is a firmware interpretation issue, not a defect in the replacement cell. One complete discharge-to-hibernate followed by a full uninterrupted charge resets the learn cycle and the warning clears.

Laptop shuts down at 20–30% charge shown on the 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 charge percentage against the old cell's declining voltage profile, so it misreads the remaining capacity. Under full CPU and display load, the cell hits its real low-voltage cutoff while the OS still shows 20–30% remaining. Run two or three complete discharge-to-hibernate and full-charge cycles — the gauge accuracy improves each time and the shutdowns stop once the IC has a reliable curve to reference.