About this replacement
Oppo Reno12 Pro / CPH2629 — 3.91V Li-Polymer Replacement Battery (BLPA57)
This is a 3.91V, 4850mAh (18.96Wh) lithium-polymer replacement battery for the Oppo CPH2629, sold under the Reno12 Pro model name. It uses OEM part number BLPA57 and matches the original cell dimensions at 90.00 × 63.00 × 4.80mm. Fit is confirmed for both CPH2629 and Reno12 Pro variants.
- CPH2629 / Reno12 Pro compatibility: Both model designations share the same physical chassis, connector pinout, and BMS handshake protocol. The BLPA57 cell communicates directly with the Reno12 Pro's charge IC — no adapter or wiring change needed.
- Bench tested on actual hardware: We ran the BLPA57 through full charge and discharge cycles on the CPH2629 platform. The BMS accepted USB-PD negotiation correctly, and the fuel gauge IC tracked state-of-charge without error flags after one complete calibration cycle.
- First-cycle fast charge protocol: On first use after installation, disable SUPERVOOC or any fast-charge mode for one full discharge-charge cycle. The fuel gauge IC needs to map the new cell's discharge curve before high-current charging can apply accurate cutoff thresholds — skipping this step risks the OS locking charge at an incorrect ceiling.
Why the Reno12 Pro reports wrong battery percentage after a cell swap
The Reno12 Pro uses a coulomb counter paired with a fuel gauge IC that builds its state-of-charge model from the original cell's impedance and discharge curve. When a new cell goes in, that model no longer matches the actual chemistry. The IC reports percentage against a stale curve, so readings can read 10–15% high or low until recalibration. One full discharge to automatic shutdown followed by a complete uninterrupted charge cycle resets the learned curve and brings percentage accuracy back in line.
Sudden shutdown at 20–30% remaining on the replacement cell
This happens when the fuel gauge IC hasn't finished calibrating and the cell hits its actual voltage floor before the OS sees it coming. Under modem or display load, voltage can sag fast enough to trip the BMS low-voltage cutoff at 3.0V per cell while the percentage gauge still shows 20–30%. The fix is the same calibration cycle — one full drain to forced shutdown, then charge to 100% without interruption. After that cycle, the coulomb counter anchors its zero point correctly and the premature cutoff stops.