BLP581 Oppo N3 Compatible Battery 3.8V 3000mAh

Oppo N3 Series — 3.8V Li-Polymer Replacement Battery (BLP581)

The BLP581 is a 3.8V, 3000mAh Li-Polymer cell for the Oppo N3, N3T, N3S, and N3 Dual SIM. It replaces the original battery when capacity has dropped, the phone shuts down unexpectedly, or the cell no longer holds a charge. Dimensions are 74.11 × 65.54 × 4.46mm — match these against your existing cell before installation.

• N3 series compatibility: The N3, N3T, N3S, and N3 Dual SIM all share the BLP581 footprint and connector pinout. The BMS handshake uses the same voltage rail and thermistor line across these variants, so one cell covers the full lineup.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on N3 hardware. The BMS accepted the cell without fault codes, held the 3.8V nominal rail under display and modem load, and hit cutoff at the expected low-voltage threshold.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard rate. The fuel gauge IC on the N3 is calibrated to the old cell's discharge curve — one slow cycle lets it remap against the new cell before fast charging applies high current to an uncalibrated state.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity fault. Under peak modem or screen load, the new cell's voltage drops faster than the fuel gauge IC expects, triggering a low-voltage shutdown before the reported percentage reaches zero. The N3's coulomb counter is still mapped to the discharge curve of the degraded original cell. One full slow cycle — charge to 100%, discharge to automatic cutoff — forces the IC to rebuild its curve against the new cell. After that cycle, shutdowns at 20–30% stop.

Oppo fast charge not activating after battery replacement

On the first charge cycle after a cell swap, the N3 may default to standard 5V charging and refuse to negotiate the proprietary fast charge protocol. This happens because the charge IC flags an uncalibrated cell state and holds back high-current delivery as a precaution. Plug into the original Oppo fast charge adapter — not a USB-PD third-party charger — and complete one full standard charge first. Fast charge typically re-enables automatically on the second cycle once the BMS has confirmed cell state.