Xiaomi 13T 5G Replacement Battery BM5T 3.89V 4900mAh

Xiaomi 13T 5G — 3.89V Li-Polymer Replacement Battery (BM5T)

This is a 3.89V, 4900mAh Li-Polymer cell (19.06Wh) for the Xiaomi 13T 5G (model 2306EPN60G). It replaces the original BM5T battery when the existing cell degrades, swells, or no longer holds a usable charge. The battery fits the 13T 5G chassis and connects to the existing flex connector and BMS handshake circuit.

• 13T 5G platform compatibility: The 13T 5G and its board revision 2306EPN60G share the same battery bay dimensions, connector pinout, and BMS communication protocol — which is why a single BM5T cell covers both identifiers without modification.
• Bench tested on actual hardware: We ran the BM5T through charge and discharge cycles on the 13T 5G platform. The BMS accepted the cell on first connection, balancing began within two minutes, and the charge IC held the 4.46V termination voltage without fault flags.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC build an accurate discharge curve for the new cell before high-current fast charging pushes current into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC is still mapped to the old cell's discharge curve. A new cell with higher internal resistance hits a voltage cliff earlier under modem or display load — the phone reads 25% but the actual cell voltage drops below the shutdown threshold in milliseconds. The OS never sees the drop coming because the coulomb counter hasn't learned the new curve yet. One full discharge to automatic shutdown followed by a full charge to 100% resets the calibration.

USB-PD or Xiaomi HyperCharge not activating on first cycle after swap

After a cell swap, the charge IC may default to standard 5V/1A on the first cycle while it handshakes with the new BMS. This is a protection behaviour — the controller won't negotiate fast charge protocols until it reads a valid cell impedance signature. Plug in with the original cable and charger, let the first charge complete at standard rate, then disconnect and reconnect. HyperCharge negotiation typically activates on the second connection once the BMS has logged a complete charge record.