BLP757 Oppo Realme 6 Replacement Battery 3.85V 4050mAh

Oppo Realme 6 / Realme 6s — 3.85V Li-Polymer Replacement Battery (BLP757)

This is a 4050mAh Li-Polymer replacement battery for the Oppo Realme 6, Realme 6s, RMX2001, and RMX2002 smartphones. It replaces OEM part number BLP757 and restores full power to the display, processor, and all onboard functions. Rated at 3.85V nominal and 15.59Wh, it matches the original cell specification exactly.

• Realme 6 / 6s platform fit: The RMX2001 and RMX2002 share the same battery bay, connector pinout, and BMS handshake protocol — one cell covers the full lineup without modification.
• Bench tested on actual hardware: We ran BLP757 on an RMX2001 unit. The BMS accepted the cell on first connect, charge IC initialised without fault codes, and the fuel gauge began tracking from zero without an error state.
• First-cycle fast charge protocol: On first use after installation, disable VOOC fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate its coulomb counter against the new cell's discharge curve before high-current charging pushes load into an uncalibrated cell.

Sudden shutdown at 20–30% on the BLP757 replacement cell

This happens because the fuel gauge IC is still using the discharge curve from the old, degraded cell. The new cell has a steeper voltage drop under modem and screen load than the old curve predicts. When voltage dips briefly under that load, the protection circuit reads it as a critically low cell and cuts power — even though capacity remains. One full discharge-to-shutdown followed by a full charge resets the coulomb counter and eliminates most of these events.

VOOC fast charging rejected on the first cycle after replacement

Realme's VOOC protocol requires a BMS handshake before the adapter steps up current. On a freshly installed cell, the BMS may not respond to the adapter's negotiation signal on the first charge cycle. Plug in via standard 5V charging first, allow the battery to reach 100%, then unplug and reconnect — the VOOC handshake succeeds once the BMS has completed one full cycle and confirmed cell voltage is stable above 4.1V.