Gigabyte Sabre 15-K8 Compatible Battery 11.1V 4400mAh

Gigabyte Sabre 15-K8 / 17-K8 Series — 11.1V Li-ion Replacement Battery (6-87-N850S-6E71)

This is an 11.1V, 4400mAh (48.84Wh) Li-ion replacement battery for the Gigabyte Sabre 15-K8, Sabre 15-G8, Sabre 17-W8, and Sabre 17-K8 notebook computers. It slots into the same bay as the original cell and connects using the same multi-pin harness. When the factory cell degrades and the laptop starts shutting down early or refusing to charge, this replaces it directly.

• Sabre 15 and 17 platform compatibility: These Sabre models share the same battery bay dimensions, 11.1V three-cell architecture, and BMS communication protocol — which is why one part number covers the full range. Swapping across these models does not require firmware changes or connector adapters.
• Bench tested on actual hardware: We ran this cell through a full charge and discharge cycle on a Sabre-platform board. The BMS handshake completed without error, charge termination triggered correctly at capacity, and the protection circuit responded normally to a simulated over-discharge event.
• First-cycle calibration on the Sabre platform: After fitting, run the laptop on battery alone until it reaches hibernate cutoff — do not interrupt. Then charge uninterrupted to 100%. This single cycle lets the BIOS battery-learn routine reset against the new cell's actual capacity curve and clears the inaccurate health warning that appears after every cell swap on this platform.

Why the Sabre shuts down at 20–30% remaining after a battery swap

The Sabre's fuel gauge IC holds a model of the old cell's discharge curve in memory. After a swap, that model no longer matches the new cell's actual voltage-versus-capacity profile. Under full CPU and display load, the voltage drops faster than the IC expects, and the system reads 20–30% remaining when the cell is actually near its lower voltage threshold. The laptop cuts power to protect the cell — even though the gauge still shows charge. Running one complete discharge-to-hibernate cycle followed by an uninterrupted full charge retrains the IC against the new chemistry and fixes the early shutdown.

BIOS reports battery health as "poor" or "unknown" immediately after install

The Sabre BIOS reads health status from EEPROM data written by the original cell's internal controller — not from a live measurement of the new cell. Immediately after swapping, that EEPROM data reflects the degraded state of the old battery, so the health warning is stale, not accurate. The battery learn cycle clears this: discharge to hibernate cutoff, then charge to 100% in one uninterrupted session. After that cycle completes, the BIOS will update the health register to reflect the new cell and the warning will clear.