Xiaomi Mi Note Pro BM34 Replacement Battery 3.85V 3000mAh

Xiaomi Mi Note Pro — 3.85V Li-Polymer Replacement Battery (BM34)

This is a 3000mAh 3.85V lithium-polymer replacement battery for the Xiaomi Mi Note Pro smartphone. It replaces OEM part BM34 and fits the Mi Note Pro directly. Capacity is 3000mAh (11.55Wh), matching the original cell specification.

• Mi Note Pro fitment: The Mi Note Pro uses a dedicated battery bay sized for a 77.68 × 63.70 × 4.00mm cell with a BM34 connector pinout. This cell shares that footprint and connector layout, so the BMS handshake between the PMIC and fuel gauge IC proceeds without modification.
• Bench tested on actual hardware: We cycled this cell through a full discharge-charge sequence on the Mi Note Pro platform and logged the BMS charge termination voltage. The fuel gauge IC accepted the new cell and charge termination triggered correctly at 4.35V without false cutoff.
• First-cycle fuel gauge recalibration: After installation, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% on standard 5V input. This gives the coulomb counter a clean reference curve before fast-charge current is applied to an uncalibrated cell.

Why the Mi Note Pro reports wrong battery percentage after a cell swap

The Mi Note Pro uses a coulomb counter inside the fuel gauge IC to track charge state. That counter holds a calibration map built against the original cell's discharge curve. A new cell has a slightly different internal resistance and discharge slope, so the stored map no longer matches real voltage behaviour. The phone reads a percentage based on the old curve and the number drifts — often reading higher than actual until the IC relearns. One full uninterrupted discharge-charge cycle on standard charge rewrites the reference map and stabilises the readout.

Sudden shutdown at 20–30% after installing the replacement cell

This happens when the fuel gauge IC's low-voltage threshold is still calibrated to the aged cell, which had a gradual voltage drop near empty. A new lithium-polymer cell holds voltage well until it hits a steep cliff around 3.5V per cell under modem or display load. The phone's PMIC triggers a hard shutdown before the reported percentage reaches zero because the actual cell voltage drops faster than the uncalibrated gauge predicts. Run two full discharge-charge cycles on standard 5V input — after that, the coulomb counter tracks the new cell's cliff correctly and shutdowns at low percentage stop.