About this replacement
Asus ZenBook Pro 14 UX450 Series — 15.4V Li-Polymer Replacement Battery (C41N1804)
This 15.4V, 4400mAh (67.76Wh) lithium-polymer battery replaces the original C41N1804 cell in the Asus ZenBook Pro 14 UX450 series. It fits the UX450FD, UX450FDX, UX480FD, and related variants that share the same internal bay and connector. Capacity figures are sourced from the product data — not inflated for marketing.
- UX450 and UX480 platform fit: These models share the same 15.4V four-cell Li-Polymer configuration, physical bay dimensions, and BMS handshake protocol — which is why one cell covers both the UX450 and UX480 lines. The connector pinout and charge communication line are identical across the platform.
- Bench tested on actual hardware: We ran this cell on a ZenBook Pro 14 chassis and monitored BMS communication through full charge and discharge cycles. The protection circuit tripped correctly at low-voltage threshold, and charge acceptance held steady across repeated cycles.
- Post-install calibration on the UX450: After fitting this cell, run one full discharge to hibernate-cutoff, 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 UX450 BIOS reports poor battery health immediately after a swap
The ZenBook Pro 14 stores learned capacity and cycle data in the EEPROM of the old cell. When a new cell goes in, the BIOS reads zero cycle history and flags the battery as degraded or unknown — this is a data mismatch, not a fault with the replacement. Running the battery learn cycle rewrites that EEPROM baseline against the new cell's actual chemistry. Until that cycle completes, Windows battery health warnings and ASUS Battery Health Charging alerts are unreliable. One full discharge-to-hibernate followed by an uninterrupted charge to 100% is enough to clear it.
UX450 shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC hasn't been calibrated against the new cell's voltage curve. Under combined CPU and display load, the cell voltage drops faster than the uncalibrated gauge predicts — the system hits the low-voltage protection threshold while the OS still shows 20–30% remaining. It's not a defective cell; it's a mapping problem between the old discharge curve in firmware and the new cell's actual behaviour. Run two full calibration cycles — discharge to hibernate-cutoff, then charge to 100% without interruption — and check that the shutdown threshold moves below 5%.