OnePlus 6 BLP657 Replacement Battery 3.85V 3300mAh

OnePlus 6 / 6 Dual SIM — 3.85V Li-Polymer Replacement Battery (BLP657)

This is a 3.85V, 3300mAh (12.71Wh) Li-Polymer cell built to the BLP657 specification for the OnePlus 6 and 6 Dual SIM. It fits all regional variants of the OnePlus 6, including the TD-LTE and Global Dual SIM models. Install it when the original cell has degraded to the point where the phone shuts down unexpectedly or no longer holds a useful charge.

• OnePlus 6 variant compatibility: Every OnePlus 6 variant — single SIM, Dual SIM, TD-LTE, and Global — uses the same BLP657 cell footprint, connector pinout, and BMS handshake. The battery management IC on this replacement communicates with the PMIC over the same protocol, so the phone recognises the cell and reports charge state normally.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on a OnePlus 6 unit and confirmed the BMS accepted the cell without fault codes. Charge current ramped correctly through CC and CV phases, and the fuel gauge IC tracked state-of-charge across the full discharge curve without erratic jumps.
• First cycle after installation: On first use, disable Warp Charge and run one complete discharge-charge cycle on standard 5V charging. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging pushes into an uncalibrated state.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity problem. Under high-current loads — modem TX bursts, screen-on GPU activity — the new cell's internal resistance causes voltage to sag below the PMIC's cutoff threshold while the fuel gauge still reports 20–30%. The phone interprets the voltage drop as a hard low-battery condition and shuts down. One full discharge-charge cycle recalibrates the coulomb counter, and the reported percentage begins to match the actual cell voltage curve accurately.

Warp Charge not activating after battery replacement

OnePlus's Warp Charge protocol requires a handshake between the charger, the cable, and the battery BMS before it enables high-current delivery. On a freshly installed cell with an uncalibrated BMS, this handshake can fail on the first cycle and the phone defaults to standard 5V/2A charging. Use the original Warp Charge adapter and cable, complete one full standard charge cycle first, then retry Warp Charge — the BMS state machine typically accepts the handshake from the second cycle onward.