About this replacement
Xiaomi Mi Play — 3.85V Li-Polymer Replacement Battery (BM3H)
The BM3H is a 3000mAh, 3.85V Li-Polymer cell for the Xiaomi Mi Play (M1901F9E, M1901F9T). It replaces the original battery when capacity has degraded or the cell has failed. Capacity figure is 11.55Wh at nominal voltage.
- M1901F9E and M1901F9T compatibility: Both regional variants of the Mi Play share the same battery bay dimensions (69.84 × 60.38 × 4.00mm), connector pinout, and BM3H part number. The BMS handshake and charge IC communication lines are identical across both SKUs.
- Bench tested on actual hardware: We cycled the BM3H through charge and discharge on Mi Play hardware and confirmed the BMS accepted charge termination correctly, with no false full-charge flags and no overcurrent trip during screen-on load testing.
- First-cycle fast charge protocol: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging pushes into an uncalibrated state.
Why the Mi Play reports wrong battery percentage after a cell swap
The Mi Play uses a coulomb-counting fuel gauge IC that builds its model against the previous cell's charge curve. When a new cell goes in, that stored model no longer matches the actual chemistry. The gauge reads an offset until it recalibrates. One full discharge to auto-off, followed by an uninterrupted charge to 100%, resets the count and re-anchors the percentage display to the new cell.
Sudden shutdown at 20–30% remaining on the replacement cell
This happens when the modem or display draws a short current spike and the cell voltage drops below the BMS cutoff threshold before the gauge registers the drop. It is not a defective cell — it is a voltage cliff the fuel gauge did not predict because it was still running the old cell's discharge model. The fix is the same recalibration cycle: drain to shutdown, charge uninterrupted to 100%, and check that the percentage tracks smoothly below 30%. If the shutdown persists past two full cycles, verify the battery connector is fully seated and check for residual voltage at the connector — it should read above 3.6V on a charged cell.