Asus ROG Zephyrus S GX531GS Replacement Battery 15.4V 3050mAh

Asus ROG Zephyrus S GX531GS — 15.4V Li-Polymer Replacement Battery (C41N1805)

This is a 15.4V Li-Polymer battery rated at 3050mAh (46.97Wh), built as a direct cell replacement for the Asus ROG Zephyrus S GX531GS and the broader GX531 series. It fits the ultra-thin chassis without modification — the GX531 line uses a flat 4.50mm profile cell that is specific to this platform. Voltage, connector, and BMS handshake all match the OEM specification (C41N1805 / 0B200-03020000).

• GX531 platform compatibility: The GX531GS, GX531GXR, GX531GX, and GX531GM variants all run the same 15.4V four-cell Li-Polymer configuration on a shared battery connector and BMS protocol. Swapping between these models works because the voltage rail and physical form factor are identical across the series.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a GX531 unit. The BMS accepted the new cell without fault codes, reported correct Wh capacity after two calibration cycles, and held voltage above the 12V cutoff floor under sustained GPU plus CPU load.
• GX531 BIOS learn cycle after install: After fitting this cell, run one full discharge to hibernate cutoff — do not interrupt it — then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning the GX531 firmware flags after every cell swap.

Why the GX531 BIOS reports poor battery health immediately after a cell swap

The GX531 firmware stores battery health data in EEPROM tied to the original cell's charge history. When a new cell is installed, that stored data no longer matches the actual cell state, so the BIOS reads it as degraded. This is a firmware interpretation issue, not a fault with the replacement cell. Running the full discharge-to-hibernate then uninterrupted charge cycle forces the BIOS to rewrite its health baseline against the new cell. After one or two completed cycles, the health status corrects itself in both the BIOS and Windows battery report.

GX531 shuts down at 20–30% charge shown on screen

This happens when the fuel gauge IC's stored discharge curve no longer maps accurately to the new cell's actual voltage profile. The laptop reads 25% remaining but the cell voltage has already dropped below the BMS cutoff threshold under combined CPU and GPU draw. It is a calibration gap — not a faulty battery. Force a complete discharge to hibernate, then charge to 100% twice without interruption. After two full cycles, the fuel gauge IC recalibrates its curve and the percentage reading aligns with actual remaining voltage.