Redmi Note 13 Pro+ BM5U Replacement Battery 3.88V 4850mAh

Redmi Note 13 Pro+ — 3.88V Li-Polymer Replacement Battery (BM5U)

The BM5U is a 3.88V, 4850mAh Li-Polymer cell that replaces the original battery in the Redmi Note 13 Pro+ (model 23090RA98C). It fits when the stock cell has degraded past the point where the phone can hold a useful charge through a normal day. Capacity figure is 18.82Wh at nominal voltage.

• Note 13 Pro+ / 23090RA98C fit: Both identifiers reference the same hardware platform. The connector pinout, BMS handshake protocol, and physical cell dimensions (85.30 × 63.00 × 6.10mm) are matched to this board revision — no adapter or modification needed.
• Bench tested on actual hardware: We ran this cell through charge initiation, BMS communication verification, and USB-PD handshake confirmation. The BMS accepted the cell on first cycle without triggering charge fault flags.
• First-cycle fuel gauge reset: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging begins on an uncalibrated cell.

Why the Note 13 Pro+ reports wrong battery percentage after a cell swap

The phone's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The IC reports percentage based on old data, so numbers can appear frozen, jump unexpectedly, or read full when the cell is not. One complete slow discharge-charge cycle forces the coulomb counter to recalibrate against the new cell's real curve.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC is still running the old cell's voltage cliff profile. The original cell may have had a gradual voltage drop at low charge; the new cell drops faster under modem or screen load at the same reported percentage. The phone interprets the voltage sag as a critical low and cuts power before the display percentage reaches zero. One full calibration cycle — full discharge to automatic shutdown, then full charge uninterrupted — resets the threshold the IC uses to trigger that cutoff.