Xiaomi Redmi Note 3 Replacement Battery BM3A 3.85V 3000mAh

Xiaomi Mi Note 3 — 3.85V Li-Polymer Replacement Battery (BM3A)

This is a 3000mAh Li-Polymer cell at 3.85V, built to the BM3A spec for the Xiaomi Mi Note 3 smartphone. It replaces an original cell that has degraded, swollen, or lost meaningful capacity. Dimensions are 78.84 × 62.94 × 3.30mm — measure your existing cell before ordering if you're unsure.

• Mi Note 3 platform fit: The Mi Note 3 uses a 3.85V nominal rail with a BM3A-keyed connector and BMS handshake. This cell matches that voltage rail and connector pinout so the charge IC communicates correctly with the new cell from the first boot.
• Bench tested on actual hardware: We cycled this cell on a Mi Note 3 unit and monitored BMS communication across charge and discharge. The protection circuit tripped correctly at voltage floor and ceiling with no false cutoffs under screen-on modem load.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated coulomb counter.

Why the Mi Note 3 reports wrong battery percentage after a cell swap

The Mi Note 3 uses a coulomb counter that learns cell capacity over charge-discharge cycles. When a new cell goes in, the IC still holds the discharge curve from the old, degraded cell. That mismatch causes the percentage to read high until load collapses it suddenly. One full uninterrupted discharge to below 5% followed by a complete charge resets the learned curve and stabilises the readout.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff problem, not a capacity problem. Under combined modem, screen, and CPU load the cell voltage drops faster than the fuel gauge expects, hitting the BMS cutoff floor while the reported percentage still reads high. A fresh BM3A cell will show this on the first few cycles until the fuel gauge recalibrates. If it persists past three full cycles, check that the connector is fully seated — a high-resistance contact causes the same voltage sag symptom. Verify resting voltage reads at least 3.85V after a full charge before ruling out a connection issue.