About this replacement
Asus ZenBook 14 OLED UX3402 — 7.74V Li-Polymer Replacement Battery (C22N2107)
This is a 7.74V, 9600mAh (74.3Wh) lithium-polymer battery for the Asus ZenBook 14 OLED UX3402 series ultrabook. It replaces OEM part C22N2107 and fits the UX3402ZA, UM3402YA, and related ZenBook 14 OLED variants. Install it when the original cell no longer holds charge, fails to charge at all, or the OS reports severely degraded battery health.
- ZenBook 14 OLED UX3402 series fitment: The UX3402ZA and UM3402YA share the same battery bay dimensions, connector pinout, and BMS handshake protocol — all routed to the C22N2107 specification. The same 7.74V two-cell polymer configuration runs across this entire platform.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on ZenBook 14 OLED hardware. The BMS communicated correctly with the EC firmware, charge current tapered as expected at capacity, and no fault codes triggered during the cycle.
- Post-install calibration on ZenBook OLED hardware: After fitting, run the laptop down to hibernate cutoff under normal load — do not force-shutdown. Then charge uninterrupted to 100%. This single full cycle resets the BIOS battery learn cycle and clears the inaccurate health warning the EC logs when it detects a new cell with no prior EEPROM history.
Why the ZenBook 14 OLED shuts down at 20–30% after a battery swap
The ZenBook EC uses a fuel gauge IC that builds its discharge model against the original cell's charge history stored in EEPROM. A new cell has no history, so the IC's state-of-charge estimate drifts early. Under combined CPU and OLED display load — which can spike draw significantly — the cell voltage drops faster than the miscalibrated gauge expects, and the EC triggers a protective shutdown before the gauge reads zero. Two or three full discharge-to-hibernate-then-full-charge cycles force the fuel gauge IC to re-map the new cell's actual voltage curve. After calibration, the reported percentage tracks real capacity accurately.
BIOS showing battery Wh rating as incorrect after fitting C22N2107
The Wh figure the BIOS displays is read from the battery's EEPROM, which holds the cell's factory-rated specification. The EEPROM on a replacement cell may carry a slightly different rated value than the original, even when the physical chemistry and voltage are identical. This is an EEPROM data difference, not a fault with the cell itself. The actual delivered capacity is governed by the chemistry, not the stored number — check capacity under real load by running a full discharge cycle and observing runtime against a known baseline.