About this replacement
Xiaomi Air 12.5 — 7.6V Li-Polymer Replacement Battery (161201-01)
This is a 7.6V, 4800mAh (36.48Wh) Li-Polymer replacement battery for the Xiaomi Air 12.5 tablet. It replaces OEM parts 161201-01, 161201-AA, 161201-AQ, and R10B01W. Fit this battery when the original no longer holds a charge or the tablet shuts down unexpectedly at partial capacity.
- Air 12.5 fit: The Air 12.5 uses a slim Li-Polymer cell with a specific connector orientation and BMS handshake tied to Xiaomi's fuel gauge IC. This replacement matches the cell dimensions (253.94 × 126.58 × 5.92mm), voltage rail, and connector so the battery registers correctly with the system board.
- Bench tested on actual hardware: We cycled this battery through charge and discharge on the Air 12.5 platform. The BMS accepted the cell without fault flags, and the charge IC stepped through trickle, constant-current, and constant-voltage phases cleanly with no cutoff errors.
- Fuel gauge recalibration after install: After fitting this battery, run one full discharge to automatic shutoff, then charge uninterrupted to 100%. This gives the fuel gauge IC a complete data set against the new cell and clears inaccurate percentage readings that commonly appear after a swap.
Xiaomi Air 12.5 shutting down at 15–25% remaining
This happens when the display backlight and Wi-Fi radio draw simultaneously pull voltage below the BMS cutoff threshold before the fuel gauge reaches 0%. The old cell's degraded curve taught the fuel gauge to expect a slower voltage drop, so the new cell's steeper cliff catches the system off guard. One full discharge-to-shutoff cycle recalibrates that curve. After the cycle, the OS percentage and the actual cell voltage align again.
Fast charging not available after battery swap
The Air 12.5 charge controller uses a USB-PD negotiation sequence that only unlocks higher wattage after one accepted full charge cycle on a new cell. Until that first cycle completes, the system defaults to standard 5V charging as a precaution. Plug into the original Xiaomi charger and let the tablet charge uninterrupted from near-empty to 100% without interruption. Fast charge should re-engage on the next session once that handshake is established.