Redmi 10C Replacement Battery BN5G 3.87V 4900mAh

Redmi 10C / 10A Series — 3.87V Li-Polymer Replacement Battery (BN5G)

The BN5G is the OEM-matched Li-Polymer cell for the Redmi 10C and 10A smartphones, including variants 220333QAG and 220333QBI. It runs at 3.87V with a 4900mAh (18.96Wh) capacity. Fit this when the original cell no longer holds charge, swells, or fails to power the device.

• 10C and 10A platform compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — the BN5G part number covers the full variant range because the fuel gauge IC and charge controller are common across these SKUs.
• Bench tested on actual hardware: We cycled the BN5G through full charge and load discharge on a 10C unit. The BMS accepted the charge controller handshake on the first cycle, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• First-cycle fast-charge protocol: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before the charge IC pushes higher current into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on the replacement BN5G cell

This is a voltage cliff failure, not a capacity fault. The phone's PMIC monitors cell voltage under load — modem transmit bursts and display brightness spikes draw current fast enough to pull the cell voltage below the shutdown threshold even when the fuel gauge still reads 20–30%. A freshly installed cell that hasn't completed a calibration cycle will hit this because the coulomb counter is still mapped to the old cell's impedance curve. Run one full discharge to auto-off, then charge uninterrupted to 100% — the fuel gauge recalibrates and the shutdowns stop.

Phone won't power on after the BN5G sat discharged in storage

Li-Polymer cells dropped below roughly 2.5V per cell trigger a BMS lockout — the protection circuit opens to prevent an unsafe charge into a deeply discharged cell. The phone won't respond to the power button and may show nothing on screen even with a cable attached. Connect to a 5V/1A charger — not a fast charger — and leave it for 20–30 minutes without pressing anything. The BMS re-initialises at a trickle rate first; once cell voltage climbs above the recovery threshold (around 3.0V), normal charging resumes and the phone will boot.