About this replacement
Asus ZenBook 15 UX534 Series — 15.4V Li-Polymer Replacement Battery (C42N1839)
This is a 15.4V, 4500mAh (69.3Wh) Li-Polymer replacement battery for the Asus ZenBook 15 UX534 series. It fits the UX534FTC-BPC1517U, UX534FT-A7601T, UX534FTC-A9076T, UX534FTC-AA196T, and over 150 additional UX534 variants sharing the same OEM part number C42N1839. It replaces a degraded or failed original cell that can no longer hold a working charge.
- UX534 series compatibility: All covered models share the same 15.4V four-cell Li-Polymer architecture, the same C42N1839 OEM part number, and the same physical connector and BMS handshake with the EC firmware. Swapping between variants in this family does not require a different battery.
- Bench tested on actual hardware: We ran this cell on UX534 hardware and confirmed the BMS handshake cleared without fault codes. The charge cycle completed without the EC triggering an early cutoff, and the protection circuit responded correctly to simulated over-discharge.
- Post-install calibration on UX534 hardware: After fitting this battery, 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 false "poor health" warning that appears in MyASUS and Windows after every cell replacement.
Why the UX534 BIOS flags a new battery as degraded on first boot
The Asus EC reads charge history and cycle count data stored in the outgoing cell's EEPROM. When a new cell arrives with zeroed or mismatched EEPROM values, the BIOS compares them against its expected baseline and logs a health warning. This is a data mismatch, not a physical fault with the replacement cell. Running one full discharge-to-hibernate followed by a complete uninterrupted charge gives the EC enough data to write a new baseline and clear the warning.
UX534 shutting down with 20–30% charge showing on screen
This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The displayed percentage is based on the old cell's learned curve, so the reading drifts high — the battery hits its low-voltage cutoff while the OS still shows capacity remaining. The fix is two to three full discharge-and-recharge cycles to let the fuel gauge IC re-map the real curve against the new cell. After calibration, shutdown should not occur until the cell drops to approximately 3.0V per cell under load.