About this replacement
Asus X551C / X551CA Series — 11.25V Li-ion Replacement Battery (A41N1308)
This is an 11.25V, 2600mAh (29.25Wh) Li-ion replacement battery for the Asus X551C and X551CA notebook series. It replaces OEM part numbers A41N1308, A31N1308, A31N1319, and several additional Asus factory codes. When the original cell degrades and your laptop no longer holds a charge unplugged, this cell restores full untethered use.
- X551C and X551CA compatibility: These models share the same 11.25V three-cell battery bay, connector pinout, and BMS communication protocol — which is why a single cell covers both the standard X551C and all X551CA sub-variants including the 0051A2117U and SX014H configurations.
- Bench tested on actual hardware: We ran this cell through charge, load, and discharge cycles on X551-series hardware. The BMS handshake completed correctly, the charge controller accepted the cell without fault codes, and voltage held stable across CPU and display load transitions.
- Post-install calibration on the X551 series: After fitting this battery, run the laptop down until Windows forces hibernate, then charge it uninterrupted to 100% without unplugging mid-cycle. The X551's BIOS uses this full discharge-to-charge pass to reset its internal battery learn cycle — skipping it leaves the fuel gauge reading inaccurate and often triggers a false "Consider replacing your battery" warning in Windows.
BIOS reporting poor battery health immediately after fitting the new cell
The X551's BIOS stores health metrics from the previous cell in EEPROM. When a new cell is installed, the BIOS compares current readings against that cached data and flags the health as poor or unknown — even though the cell is brand new. This is not a fault with the replacement battery. Run one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100%, and the BIOS learn cycle will overwrite the stale EEPROM values. After two to three cycles, health reporting normalises.
Laptop shutting down at 20–30% charge shown on screen
This happens when the fuel gauge IC still holds calibration data from the old, degraded cell. The displayed percentage does not match actual cell voltage — the laptop shuts down because voltage drops below the hardware cutoff threshold before the gauge reaches 0%. It is a calibration gap, not a defective replacement cell. Force a full discharge to hibernate cutoff, charge uninterrupted to 100%, and repeat once more — after two calibration cycles the gauge tracks actual cell voltage accurately and shutdowns at false percentages stop.