About this replacement
Asus ZenBook 14 UX434FL Series — 11.55V Li-Polymer Replacement Battery (C31N1841)
This is a 11.55V, 4200mAh (48.51Wh) Li-Polymer replacement battery for the Asus ZenBook 14 UX434FL-AI034R and a wide range of UX434 and UX463 variants. It uses OEM part numbers C31N1841 and 0B200-03420200. The battery fits the slim chassis of the UX434 series without modification to connector, orientation, or cell thickness.
- UX434 and UX463 platform compatibility: These models share the same 3-cell Li-Polymer architecture, 11.55V voltage rail, and ZIF connector pinout. The BMS handshake protocol is identical across UX434FL, UX434FLC, and UX463FA variants, so one cell works across the full cluster.
- Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a UX434FL unit. The BMS accepted the cell without error codes, charge current stepped down correctly at the 4.2V-per-cell threshold, and the protection circuit tripped cleanly at the low-voltage cutoff.
- Post-install calibration cycle: After fitting this cell, run the laptop down to hibernate cutoff on battery only — no AC during discharge — then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap.
Why the ZenBook 14 shuts down at 20–30% after a battery swap
The BIOS fuel gauge IC maps voltage curves from the previous cell's EEPROM data. A new cell has different internal resistance and a slightly different discharge curve, so the gauge misreads the remaining capacity. Under full CPU and display load, the new cell hits a voltage cliff the old EEPROM data didn't predict, and the system cuts power before the indicator reaches zero. Running one full calibration cycle — discharge to hibernate, then a full uninterrupted charge — rewrites the gauge mapping to match the new cell's actual curve.
BIOS reporting battery health as "poor" or "replace" immediately after fitting
This is an EEPROM mismatch, not a fault with the new cell. The BIOS reads health data stored in the old cell's embedded controller and compares it against the new cell's reported Wh value — the figures don't match, so it flags a warning. The fix is a single battery learn cycle: boot into Windows, disconnect AC, let the laptop discharge fully to auto-hibernate, then plug in and charge to 100% without interruption. After one complete cycle, the BIOS recalibrates and the health warning clears.