Xiaomi Redmi 10C Replacement Battery BN5G 3.87V 4900mAh

Xiaomi Redmi 10C — 3.87V Li-Polymer Replacement Battery (BN5G)

The BN5G is a 3.87V, 4900mAh Li-Polymer cell that fits the Xiaomi Redmi 10C and its regional variants including 220333QAG, 220333QBI, and 220333QNY. It replaces a degraded original cell when the phone can no longer sustain a full day on a single charge. Capacity figures here come directly from the product specification — 18.96Wh total energy.

• Redmi 10C variant compatibility: Xiaomi released the Redmi 10C under multiple regional model numbers — 220333QAG, 220333QBI, 220333QNY, and three further SKUs — but all share the same battery bay dimensions (97.00 × 65.00 × 4.10mm), the same 3.87V nominal rail, and the same BN5G connector pinout. One cell covers all of them.
• Bench tested on actual hardware: We ran the BN5G through charge and discharge cycles on the Redmi 10C platform. The BMS accepted the cell without error flags, the charge IC ramped to full current, and the fuel gauge IC registered capacity without prompting a recalibration warning on the first cycle.
• Fuel gauge recalibration after installation: On first use after swapping this cell in, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% on standard 10W. This gives the coulomb counter a clean reference curve before high-current charging sessions begin.

Sudden shutdown at 20–30% on the Redmi 10C after a cell swap

A new Li-Polymer cell has a slightly different discharge curve than the worn cell the fuel gauge IC was calibrated against. When the phone's coulomb counter expects remaining capacity but the new cell's voltage drops sharply under modem or display load, the BMS cuts output before the reported percentage reaches zero. This is not a defective cell — it is a calibration mismatch. One full discharge-to-shutdown followed by a complete charge to 100% resets the reference points the fuel gauge uses, and the shutdowns stop.

Xiaomi's fast charging protocol not activating on the first cycle after replacement

Xiaomi's proprietary fast charge handshake runs a voltage negotiation between the charger and the charge IC. On a freshly installed cell, the BMS may reject the elevated current on the first charge because it has no prior state-of-health data to validate the request against. This causes the phone to fall back to standard 5W charging on that first session. Charge fully once at standard rate, let the phone complete a full discharge cycle, then plug into the fast charger — the handshake succeeds once the BMS has one full cycle of data at 3.87V nominal.