Oppo Realme C15 BLP793 Compatible Battery 3.85V 5000mAh

Oppo Realme C15 / C12 — 3.85V Li-Polymer Replacement Battery (BLP793)

The BLP793 is a 3.85V, 5000mAh Li-Polymer cell that replaces the original battery in the Realme C15 (RMX2186) and Realme C12 (RMX2189). It fits when the stock cell has degraded, swells, or can no longer hold usable charge. Capacity figure is 19.25Wh at rated voltage.

• Realme C15 and C12 compatibility: Both the RMX2186 and RMX2189 use the same BLP793 footprint, connector pinout, and BMS handshake protocol. The 88.26 × 63.84 × 4.82mm cell fits the shared chassis without modification.
• Bench tested on actual hardware: We ran the BLP793 through full charge and discharge cycles on the RMX2186. The BMS accepted the charge IC handshake on the first cycle, and overvoltage cutoff triggered correctly at the top-of-charge threshold — no false trips under screen-on load.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard rate. The fuel gauge IC on Realme devices calibrates its coulomb counter against the actual discharge curve of the new cell — skipping this step causes percentage drift and early shutdown warnings for the first several cycles.

Why the Realme C15 reports wrong battery percentage after a cell swap

The Realme C15 uses a coulomb-counting fuel gauge IC that builds its state-of-charge model from the cell it was originally calibrated against. When a new BLP793 goes in, that model no longer matches the actual discharge curve of the fresh cell. The IC may report 15–20% remaining when the true voltage is still above 3.7V, or it may drop suddenly from 30% to 0%. One full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the IC to rewrite its reference curve. After that single cycle, percentage reporting stabilises.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem, display, or a background app spikes current draw and the cell voltage sags below the BMS protection threshold — typically 3.0V per cell — faster than the fuel gauge IC anticipates. It is not a defective cell; it is the uncalibrated gauge misreading available capacity under load. Run the full recalibration cycle described above first. If shutdowns continue after calibration, check that the battery connector is fully seated — a partially connected cell raises internal resistance and causes voltage sag under any moderate load spike.