Sager NP6659 Replacement Battery 11.1V 4400mAh Li-ion

Sager NP6659 / NP2670 Series — 11.1V Li-ion Replacement Battery

This is a 11.1V, 4400mAh (48.84Wh) Li-ion battery for the Sager NP6659, NP2670, NP5653, NP2650, and related notebooks. It slots into the same battery bay as the original and uses the same connector. Install it when the original cell no longer holds a useful charge between sessions.

• NP6659 / NP2670 platform compatibility: These models share a common battery bay spec, connector pinout, and BMS handshake protocol across the series. One cell fits the group because Sager used the same power rail and SMBus communication line across these chassis generations.
• Bench tested on actual hardware: We cycled this cell through charge, full-load discharge, and low-voltage cutoff. The BMS tripped correctly at the floor voltage and accepted a full recharge without fault flags. Cell capacity matched the rated 4400mAh within tolerance.
• First-cycle calibration on the NP6659: After installing, run one full discharge to the hibernate cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell and clears the inaccurate health warning that appears after every cell swap.

BIOS reporting poor battery health after replacement on the NP6659

The NP6659 BIOS reads health data stored in the battery's EEPROM. A new cell ships with default EEPROM values that don't match what the BIOS expects after years of tracking the old cell. The system flags this mismatch as degraded health — even though the cell is new. Running the battery learn cycle described above rewrites those baseline values and clears the warning within one to two full charge cycles.

Laptop shutting down at 20–30% shown on the gauge

This happens when the fuel gauge IC hasn't finished calibrating against the new cell's actual discharge curve. The IC inherited learned cutoff points from the old, degraded cell and applies them to the new one — calling 25% as empty. It is not a battery fault. Run two to three complete discharge-to-hibernate, charge-to-100% cycles and the gauge will recalibrate. After the third cycle, the shutdown point should realign to the true low-voltage floor near 9V.