About this replacement
Oppo R6607 / U3 — 3.8V Li-Polymer Replacement Battery (BLP585)
This is a 3.8V, 3000mAh (11.4Wh) Li-Polymer cell built to the BLP585 specification. It fits the Oppo R6607 and U3 smartphones directly. Install it when the original cell no longer holds a useful charge or fails to power the phone at all.
- R6607 and U3 share this cell: Both models run the same battery bay dimensions (95.95 × 68.36 × 3.73mm), the same 3.8V nominal rail, and the same BLP585 connector pinout. The charge IC and BMS handshake are identical across both, so one part number covers both devices without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the R6607 platform. The BMS accepted the handshake cleanly, charge current stepped correctly through CC/CV phases, and the protection circuit tripped at expected over-voltage and over-current thresholds.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle at standard current. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging is applied to an uncalibrated cell.
Why the R6607 reports wrong battery percentage after a cell swap
The fuel gauge IC in the R6607 stores a learned discharge curve from the old cell. When a new cell goes in, the IC still references that old curve, so percentage readings drift immediately. The coulomb counter needs at least one full uninterrupted discharge and charge cycle to re-anchor its reference points. Until that cycle completes, the OS will report percentages that do not match actual cell state. Run one complete cycle from 100% down to automatic shutdown, then charge to full without interruption.
Sudden shutdown at 20–30% on the BLP585 replacement cell
This happens when the cell voltage drops sharply under the combined load of the modem radio and display — a voltage cliff that the fuel gauge IC does not anticipate because it is still calibrated to the degraded curve of the original cell. The new cell has a different internal resistance profile, so the voltage sag under peak current draw hits the protection threshold before the percentage counter reaches zero. The phone reads 25% but the cell is already below the cutoff voltage under load. Complete two full charge-discharge cycles and the fuel gauge IC will recalibrate — the shutdowns will stop once the counter matches the new cell's actual voltage curve.