Xiaomi Redmi Note 10 BN59 Replacement Battery 3.87V 4800mAh

Xiaomi Redmi Note 10 — 3.87V Li-Polymer Replacement Battery (BN59)

This is a 3.87V, 4800mAh (18.58Wh) Li-Polymer replacement battery for the Xiaomi Redmi Note 10, covering models M2101K7AI and M2101K7AG. It replaces the original BN59 cell when the existing battery degrades, swells, or can no longer hold a charge through a full day. Dimensions are 87.20 × 63.00 × 5.10mm — a direct physical match to the stock cell compartment.

• Redmi Note 10 compatibility (M2101K7AI / M2101K7AG): Both model variants run the same 3.87V power rail and use the same BN59 connector pinout. The BMS handshake is identical across these SKUs, so one cell covers the full Note 10 range without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Note 10 unit. The BMS accepted the new cell without fault codes, and the charge IC cycled correctly through trickle, CC, and CV phases under standard 18W charging.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes into an uncalibrated coulomb counter — preventing erratic percentage readings from the first day.

Why the Redmi Note 10 reports wrong battery percentage after a cell swap

The Redmi Note 10 uses a coulomb-counter fuel gauge IC that stores a learned discharge profile from the previous cell. When a new cell goes in, the IC still references the old curve — so the percentage shown on screen does not match actual charge state. This mismatch clears after one full discharge down to automatic shutdown and a full uninterrupted charge back to 100%. Do not top up mid-cycle during this first pass. After that single calibration cycle, the gauge tracks the new BN59 cell accurately.

Sudden shutdown at 20–30% on the new cell

This is a voltage cliff issue, not a capacity fault. Under peak modem load or high screen brightness, the cell voltage drops sharply — and if the fuel gauge IC still holds the old cell's internal resistance profile, it misjudges the remaining usable voltage. The phone shuts down before the gauge hits zero because the SoC's under-voltage protection trips first. Run the one full calibration cycle described above, and the IC recalculates the voltage floor against the new cell. After calibration, shutdowns below 3.4V per cell should stop.