Xiaomi Redmi Go BN3A Compatible Battery 3.85V 2900mAh

Xiaomi Redmi Go — 3.85V Li-Polymer Replacement Battery (BN3A)

This is a 3.85V, 2900mAh Li-Polymer cell replacing part number BN3A in the Xiaomi Redmi Go smartphone. It fits models M1903C3GH and M1903C3GG. Swap it in when the original cell no longer holds a charge or causes unexpected shutdowns.

• Redmi Go compatibility: The M1903C3GH and M1903C3GG share the same battery bay geometry, connector pinout, and BMS handshake. All three model variants accept the BN3A cell without modification to the flex cable or connector bracket.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Redmi Go unit. The BMS accepted the new cell, protection thresholds triggered correctly at the low-voltage floor, and the charge IC completed a full cycle without fault flags.
• Fuel gauge recalibration on first use: After installation, disable fast charging and run one complete discharge-to-charge cycle before normal use. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Why the Redmi Go reports wrong battery percentage after a cell swap

The Redmi Go uses a coulomb counter in the fuel gauge IC that builds its model against the old cell's charge curve. When a new cell goes in, the stored curve no longer matches the actual cell chemistry. The gauge reads voltage and projects capacity using outdated data, so it shows incorrect percentages — often wildly optimistic in the upper range and pessimistic near the bottom. One full discharge down to auto-shutoff followed by a complete charge cycle forces the IC to rebuild its reference and restore accurate readings.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC still holds a stale calibration from the old cell. At around 20–30% as reported by the OS, the actual cell voltage drops sharply under modem or screen load — a voltage cliff the old curve didn't anticipate. The BMS hits its low-voltage cutoff and shuts the device down before the displayed percentage reaches zero. Run one full discharge cycle to auto-shutoff, then charge uninterrupted to 100%; the gauge IC recalibrates and the shutdowns stop.