About this replacement
Asus M50 / N61 / X64 Series — 11.1V Li-ion Replacement Battery (A32-M50)
This is an 11.1V, 4400mAh (48.84Wh) Li-ion battery for Asus M50, M51, M50S, M50Q, N61, X64, and related notebook series. It replaces OEM part A32-M50 and cross-references including A32-N61 and A32-X64. If your original cell no longer holds charge or the laptop shuts down unexpectedly on battery, this is the direct cell swap.
- M50, N61, and X64 platform compatibility: These three Asus notebook lines share the same 11.1V three-cell-series architecture, identical connector pinout, and compatible BMS communication protocol — which is why one cell part number spans all of them. Voltage rails and charge termination logic match across the group.
- Bench tested on actual hardware: We cycled this cell through charge, full-load discharge, and BMS fault recovery. The protection circuit tripped correctly at low-voltage cutoff and recovered cleanly on reconnect. Charge termination at 12.6V was within spec across multiple runs.
- Post-install calibration on Asus M-series: After installing, run one full discharge until the laptop hibernates on its own, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on this platform.
Why the Asus M50 shuts down at 20–30% shown on the fuel gauge
The fuel gauge IC on the M50 platform was calibrated against the original cell's discharge curve. A new cell has a slightly different voltage-versus-capacity slope, so the IC reads 25% remaining while the actual terminal voltage has already dropped below the CPU-plus-display load floor. Under full load — backlit screen, active processor — voltage collapses faster than the gauge predicts. Run two full discharge-to-hibernate cycles back-to-back and the gauge IC re-learns the new curve, pushing the shutoff point down to where it belongs.
BIOS reporting poor battery health or "unknown" immediately after swap
The Asus BIOS reads health status from EEPROM data embedded in the battery's BMS — not from measured capacity. A new cell ships with factory EEPROM values that don't match the learned data the BIOS stored for the old cell, so it flags the status as degraded or unknown. This is not a fault with the replacement cell. Complete one full discharge-to-hibernate cycle followed by a full uninterrupted charge to 100%, and the BIOS will rewrite its stored health baseline against the new cell's data.