Lenovo Xiaoxin Air 12 WiFi Replacement Battery 7.6V 4900mAh

Lenovo Xiaoxin Air 12 — 7.6V Li-Polymer Replacement Battery (5B10L54987)

This 7.6V, 4900mAh (37.24Wh) Li-Polymer cell replaces the original battery in the Lenovo Xiaoxin Air 12 WiFi, Xiaoxin Air 12 6Y30, Xiaoxin Air 12 LTE, and related 12-inch Xiaoxin Air variants. It matches the OEM flat-pack dimensions at 264.84 x 187.00 x 3.50mm and uses the same connector and BMS data lines as the factory unit. When the original cell no longer holds adequate charge after repeated cycles, this is the direct cell swap.

• Xiaoxin Air 12 series fit: All listed Xiaoxin Air 12 variants share the same 7.6V battery bay, flat-pack form factor, and BMS communication protocol over the same connector pinout — one cell covers the entire sub-series without modification.
• Bench tested on actual hardware: We ran the cell through charge and discharge on a Xiaoxin Air 12 board. The BMS handshake completed correctly, charge termination triggered at the expected voltage ceiling, and the protection circuit tripped cleanly at the low-voltage cutoff threshold.
• First-cycle reset after install: After fitting the new cell, run one full discharge down to hibernate cutoff, then charge uninterrupted to 100% without suspending the machine. This forces the BIOS battery learn cycle to reset against the new cell's actual capacity curve and clears the false health warning that appears after every cell swap.

BIOS reporting battery health as poor immediately after replacement

The Xiaoxin Air 12 BIOS reads health data from the battery's EEPROM, which stores cycle count, rated capacity, and charge history. A new cell arrives with EEPROM values the BIOS hasn't yet mapped against observed charge cycles, so it flags the pack as degraded before any calibration has occurred. This is a fuel gauge IC calibration gap — not a fault with the new cell. Run one full discharge-to-hibernate then a full uninterrupted charge to 100% and the health reading normalises within two to three cycles.

Laptop shuts down at 20–30% charge shown on the fuel gauge

This happens when the fuel gauge IC is still calibrated against the old cell's voltage curve. As the new cell approaches a lower state of charge, its actual voltage drops faster than the IC expects — the board sees a voltage cliff and triggers an emergency shutdown before the displayed percentage reaches zero. The fix is a full recalibration cycle: discharge the machine under normal CPU and display load until it hibernates, then charge straight to 100%. After two full cycles the fuel gauge IC maps the new cell's curve accurately and the premature shutdowns stop.