About this replacement
Asus Vivobook A501L Series — 11.1V Li-Polymer Replacement Battery (B31N1429)
This 11.1V, 4200mAh (46.62Wh) lithium-polymer battery replaces part number B31N1429 in the Asus Vivobook A501L and A501LX series. It fits the A501LX-DM023H, A501LB5200, and over 140 additional Vivobook variants sharing the same connector and voltage rail. Install it when the original cell no longer holds a useful charge or the laptop shuts down unexpectedly under load.
- A501L and A501LX platform fit: These models share the same 11.1V three-cell architecture, identical 278.50 × 84.70 × 7.10 mm form factor, and a common BMS handshake over the SMBus line — so one cell covers the full range without pin remapping or firmware workarounds.
- Bench tested on actual hardware: We ran this cell in an A501LX chassis. The BMS initialised on first boot, the SMBus handshake completed within one POST cycle, and the charge controller accepted a full CC-CV charge to 100% without tripping the protection circuit.
- Post-install calibration on the A501L: After fitting, run the battery down to hibernate-cutoff under normal use — browser, display at full brightness — then charge uninterrupted to 100%. This forces the Asus fuel gauge IC to recalibrate against the new cell and clears the false low-health flag that BIOS logs after every cell swap.
Laptop shutting down at 20–30% remaining after battery swap
The A501L's fuel gauge IC retains charge-curve data from the old, degraded cell in its EEPROM. When a new cell is installed, the stored curve no longer matches the actual voltage profile, so the IC miscalculates the remaining capacity. Under combined CPU and display load, the cell voltage drops faster than the stale curve predicts, and the system hits the low-voltage cutoff before the displayed percentage reaches zero. One full discharge-to-hibernate followed by an uninterrupted charge to 100% rewrites the learned curve and resolves the premature shutdown.
BIOS reporting battery health as poor immediately after fitting a new cell
The Asus BIOS reads health status from a wear register stored in the battery's EEPROM — not from live voltage measurements. A brand-new cell ships with that register unwritten or set to factory defaults, which the BIOS interprets as a degraded or unknown state. This is a data mismatch, not a fault with the cell itself. Run two full discharge-and-charge cycles and the wear register updates to values the BIOS recognises as healthy, clearing the warning.