BLP913 Oppo K9X Replacement Battery 3.87V 4800mAh

Oppo K9X / PGCM10 — 3.87V Li-Polymer Replacement Battery (BLP913)

The BLP913 is a 3.87V, 4800mAh Li-Polymer cell that fits the Oppo K9X, K9x 5G 2021, and PGCM10 smartphones. It replaces the original cell when capacity has dropped or the battery no longer holds a usable charge. Capacity figure is 18.58Wh as rated on the cell.

• K9X / PGCM10 platform fit: These three model designations share the same PCB layout, connector pinout, and BMS handshake protocol — all route to the same BLP913 cell. No adapter or rewiring needed.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a K9X unit and monitored BMS handshake, charge current ramp, and cutoff voltage. The BMS accepted the cell and held charge termination at the correct upper threshold without error flags.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. The fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve. Skipping this step causes the OS to report inaccurate percentages until recalibration completes.

Sudden shutdown at 20–30% on the K9X after a cell swap

This is a voltage cliff problem, not a capacity problem. The new cell's discharge curve differs slightly from the aged cell the fuel gauge IC was calibrated against. Under high-current load — modem transmission, screen at full brightness, GPS active — the cell voltage drops faster than the IC predicts. When voltage falls below the BMS protection threshold before the percentage counter reaches zero, the phone cuts power instantly. One full discharge-charge cycle with fast charging off resets the coulomb counter and eliminates most cliff shutdowns.

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

After a cell swap, the charge IC may fall back to standard 5V/1A input on the first cycle. The proprietary VOOC handshake requires the BMS to report a valid cell state before the adapter steps up current. A new, uncalibrated cell sometimes returns a state-of-charge value that triggers a conservative fallback. Charge the phone fully at standard rate on that first cycle — by the second cycle, the BMS reports a stable cell state and VOOC negotiation completes normally.