BenQ R55 11.1V Replacement Battery 90-NFY6B1000Z 6600mAh

BenQ R55 — 11.1V Li-ion Replacement Battery (90-NFY6B1000Z)

This 11.1V, 6600mAh Li-ion battery replaces the original cell in the BenQ R55 notebook. It restores portable operation after the factory battery has degraded through repeated charge cycles. Capacity figure is 73.26Wh — matched to the original specification.

• R55 platform fit: The R55 shares its battery connector, voltage rail, and BMS handshake protocol with several ASUS and Acer-era platforms from the same period — which is why the parts list carries a long tail of cross-reference OEM numbers. The cell itself communicates capacity and health data over a single-wire SMBus line to the BIOS.
• Bench tested on actual hardware: We ran this cell through a full charge and discharge cycle on the R55 platform. The BMS accepted the EEPROM handshake on first connection, reported correct voltage to the OS, and held charge through a complete discharge without mid-cycle cutoff.
• Post-install calibration on the R55: After fitting this cell, run one full discharge until the laptop hibernates at low-battery cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning the R55 BIOS flags after every cell swap.

Why the R55 BIOS reports poor battery health immediately after replacement

The R55 BIOS stores learned capacity data from the previous cell in non-volatile memory. When a new cell connects, the BIOS compares live readings against that stored profile and flags a mismatch as degraded health. This is not a fault with the replacement cell — it is stale EEPROM data from the old battery. Running one complete discharge-to-hibernate followed by a full uninterrupted charge clears the stored profile and lets the BIOS re-learn against the new cell. After two to three cycles the health indicator should read normal.

R55 shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual chemistry. The gauge was trained on the old, degraded cell and reads remaining capacity too optimistically until it sees a full discharge curve from the replacement. Under combined CPU and display load, voltage drops faster than the uncalibrated gauge expects, hitting the hardware cutoff threshold while the OS still shows 20–30% remaining. Force a full discharge to hibernate cutoff — do not interrupt it — then charge to 100% at 12.6V and repeat once more. After two calibration cycles the shutdown point corrects to within a few percent of actual depletion.