OnePlus One BLP571 Compatible Battery 3.8V 3100mAh

OnePlus One (A0001) — 3.8V Li-Polymer Replacement Battery (BLP571)

This is a 3.8V, 3100mAh Li-Polymer cell built to the BLP571 specification for the OnePlus One (model A0001). It fits the original battery bay without modification and reconnects to the same charge IC and fuel gauge IC the phone shipped with. Capacity is rated at 11.78Wh.

• One and A0001 fitment: Both designations reference the same hardware revision — same voltage rail, same connector pinout, and the same Qualcomm PM8941 PMIC that manages charge current and BMS communication. One replacement cell covers both.
• Bench tested on actual hardware: We cycled the cell through charge and discharge on the OnePlus One board. The BMS accepted the cell without triggering an over-voltage or under-voltage fault, and charge termination landed correctly at 4.35V.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard current. This lets the fuel gauge IC map its coulomb counter against the new cell's discharge curve before higher charge rates are applied to an uncalibrated cell.

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

The OnePlus One's fuel gauge IC holds a learned discharge curve from the old cell. When a new cell with a different internal resistance is installed, the gauge's voltage-to-percentage mapping is off. Under high-current loads — modem transmission bursts or screen-on spikes — the new cell's actual terminal voltage drops below the shutdown threshold while the gauge still reads 20–30%. The fix is one full discharge to auto-off followed by a full charge without interruption. After that single cycle the coulomb counter resets and the percentage readout stabilises.

OnePlus One not powering on after the replacement battery sat in storage

Li-Polymer cells self-discharge during storage. If the BLP571 cell dropped below roughly 2.5V before installation, the BMS enters lockout mode and blocks charge current to prevent copper plating on the anode. The phone shows nothing — no charging animation, no boot. Connect it to a 5V USB source and leave it for 15–20 minutes without pressing the power button; the charge IC trickle-charges the cell at low current until it clears the BMS re-enable threshold near 2.8V. Once the charging LED activates, normal charge can proceed.