About this replacement
Xiaomi Notebook Pro X 15 — 11.55V Li-Polymer Replacement Battery (R15B05W)
This is an 11.55V, 6900mAh (79.7Wh) Li-Polymer replacement battery for the Xiaomi Notebook Pro X 15 and Pro X15 laptops. It replaces OEM part number R15B05W when the original cell has degraded or stopped holding charge. Dimensions are 297.70 × 89.80 × 9.30mm — verify against your existing pack before fitting.
- Notebook Pro X 15 and Pro X15 compatibility: Both model names share the same chassis, connector pinout, and BMS handshake protocol. One cell fits both. The R15B05W part number is the correct reference for both variants.
- Bench tested on actual hardware: We ran this cell through charge-discharge cycles on the Notebook Pro X 15 chassis. The BMS negotiated correctly with the EC firmware, and protection circuits tripped at expected low-voltage thresholds without nuisance cutoffs.
- Post-install calibration on the Notebook Pro X 15: After fitting, run one full discharge down to hibernate-cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to reset against the new cell's EEPROM data and clears the false "poor health" warning that appears after every cell swap.
BIOS reporting poor battery health immediately after swap
The Xiaomi Notebook Pro X 15 EC reads cycle count and health data stored in the old cell's EEPROM. When a new cell arrives, that EEPROM counter reads as mismatched against the firmware's learned profile. Windows Battery Report and the BIOS health screen both flag this as degraded. One full discharge-to-hibernate followed by a complete uninterrupted charge resets the learn cycle and aligns the reported health with the actual new-cell baseline.
Laptop shutting down at 20–30% charge shown on screen
This is a voltage cliff symptom, not a gauge error. Under combined CPU boost and display load, the cell voltage drops faster than the fuel gauge IC recalculates — the EC trips a hard shutdown before the displayed percentage reaches zero. The fuel gauge IC needs two to three full calibration cycles against the new cell before its discharge curve model stabilises. Run those cycles under normal workload and the shutdown threshold will settle back to the correct low-voltage cutoff near 5–8% displayed.