Xiaomi Mi 10 BM4N Replacement Battery 3.85V 4650mAh

Xiaomi Mi 10 / Mi 10S 5G — 3.85V Li-Polymer Replacement Battery (BM4N)

The BM4N is the OEM-spec lithium-polymer cell for the Xiaomi Mi 10, Mi 10 5G, Mi 10S 5G, and M2102J2SC. It runs at 3.85V nominal and delivers 4650mAh (17.9Wh). This replacement fits the same footprint and connector as the original factory cell.

• Mi 10 / Mi 10S 5G platform fit: All four models in this group share the same battery bay dimensions (118.00 × 40.70 × 5.50mm), the same 3.85V rail, and the same BM4N connector pinout with BMS handshake lines — one cell covers all variants.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Mi 10 board. The BMS accepted the new cell on first connection, protection circuits responded correctly at cutoff, and the charge IC reported no faults through a full cycle.
• Fuel gauge recalibration on first use: After installing this cell, disable fast charging and run one complete discharge-charge cycle at standard rate. The fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve — skipping this step before fast charging pushes high current into an uncalibrated cell.

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

A new cell has a slightly different internal resistance curve than the aged cell the fuel gauge IC was calibrated to. Under a high-current load — 5G modem, sustained screen brightness, or video encode — the cell voltage drops faster than the gauge predicts, and the BMS trips protection before the reported percentage hits zero. This is not a fault with the replacement cell. One full discharge-charge cycle at standard rate lets the coulomb counter remap to the new curve. After that cycle, the shutdown threshold should stabilise above 5%.

USB-PD or Xiaomi fast charge not accepted on first cycle after replacement

On first connection, the new BMS may not immediately complete the handshake with the Mi 10's charge IC — the phone falls back to standard 5W charging or shows no fast-charge indicator. This is a known first-cycle behaviour with replacement polymer cells; the BMS needs one standard-rate charge to fully initialise. Plug into a standard 5V charger and let the phone charge to 100% without interruption. After that initialisation cycle, reconnect the fast charger and confirm the fast-charge icon appears within 30 seconds of plugging in.