Oppo F15 Replacement Battery BLP515 3.7V 1450mAh

Oppo F15 / X903 / R801 — 3.7V Li-ion Replacement Battery (BLP515)

This is a 3.7V, 1450mAh Li-ion cell that replaces the original BLP515 battery in the Oppo F15, X903, R801, and T703 smartphones. It restores full device function when the original cell has degraded or failed. Dimensions are 64.80 × 42.00 × 5.00mm — confirm these against your existing cell before fitting.

• F15 / X903 / R801 / T703 platform fit: These models share the BLP515 footprint, connector pinout, and BMS handshake protocol. The charge IC on each device expects the same thermistor response and cell impedance range, so one cell fits the full group without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on an F15 unit. The BMS accepted the cell without fault codes, and the charge IC held current within the expected taper curve at end-of-charge.
• First-cycle calibration on the F15: After fitting, disable fast charging in settings and complete one full discharge-charge cycle on standard charge. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging loads an uncalibrated coulomb counter.

Why the F15 reports wrong battery percentage after a cell swap

The fuel gauge IC in the F15 stores a learned discharge curve from the original cell. When you fit a new BLP515, that stored curve no longer matches the new cell's actual voltage-to-capacity profile. The OS reads voltage against the old map and displays incorrect percentages — typically showing full charge sooner than actual capacity, or dropping suddenly near the bottom. One complete slow discharge-charge cycle lets the coulomb counter rebuild its reference curve against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC has not yet calibrated to the new cell and the phone enters a high-draw state — modem handshake, screen-on burst, or GPS fix. The cell voltage drops below the BMS cutoff threshold faster than the OS expects, triggering an abrupt shutdown even though the displayed percentage reads mid-range. It is not a faulty cell. Run the phone down to below 5% without interruption, then charge fully to 100% — after one complete cycle the gauge recalibrates and the shutdowns stop. Target a full charge endpoint of 4.2V.