Asus UX310 11.4V Replacement Battery B31N1535 45.6Wh

Asus UX310 Series — 11.4V Li-Polymer Replacement Battery (B31N1535)

This 11.4V, 4000mAh (45.6Wh) Li-Polymer battery replaces the original B31N1535 cell in the Asus UX310, UX310UA, UX310UA-1A, UX310UA-1C, and related ultrabook variants. It fits the standard three-cell bay and uses the same connector and BMS communication protocol as the factory unit. Capacity figure is sourced from product data — not web estimates.

• UX310 series compatibility: All listed UX310 variants share the same 11.4V three-cell bus, identical connector pinout, and the same BMS handshake protocol — which is why one cell covers the full range. No adapter or wiring change needed.
• Bench tested on actual hardware: We ran this cell through charge, full discharge, and charge cycles on a UX310UA. The BMS reported correct voltage at each state-of-charge step, and the protection circuit tripped cleanly at the low-voltage cutoff threshold without forcing a hard shutdown.
• First-cycle calibration on UX310: After installing, drain the laptop fully until it hibernates, then charge uninterrupted to 100% without waking the system mid-cycle. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears in MyASUS or Windows after every cell swap.

Why the UX310 shuts down at 20–30% after a battery swap

The UX310's fuel gauge IC builds a discharge curve map against the original cell's EEPROM data. When you swap the cell, that map no longer matches the new cell's actual voltage profile. Under combined CPU and display load, the system hits a voltage cliff — the cell drops faster than the old map predicts, and the firmware triggers an emergency shutdown before the gauge reads zero. Running two or three full discharge-to-hibernate cycles re-trains the fuel gauge IC against the new cell and eliminates the early cutoff.

MyASUS reports 0% or "unknown" battery immediately after installation

This happens because the BIOS reads health and cycle data stored in the old cell's EEPROM — data the new cell does not carry. The operating system and MyASUS health tool pull that cached BIOS value, not a live reading, so they display 0% or an unknown state on first boot. A full discharge-to-hibernate followed by a complete charge to 100% forces the BIOS to re-run its battery learn cycle and write fresh data. After one complete cycle the reported health figure will update to reflect the actual new cell.