About this replacement
Oppo R17 Series — 3.85V Li-Polymer Replacement Battery (BLP681)
The BLP681 is a 3.85V, 3400mAh (13.09Wh) Li-Polymer cell for the Oppo R17, R17 Dual SIM, R17 Dual SIM TD-LTE, and PAGT00. It replaces the original cell when capacity has dropped, the phone shuts down unexpectedly, or the battery no longer accepts a full charge. Dimensions are 78.55 × 64.20 × 3.92mm — confirm your existing cell matches before fitting.
- R17 and PAGT00 compatibility: All four models in this fit list share the same 3.85V power rail, BLP681 connector footprint, and BMS handshake protocol. Swapping between variants does not require firmware changes — the charge IC communicates the same way across the R17 lineup.
- Bench tested on actual hardware: We cycled this cell through the R17's VOOC charge IC and confirmed BMS handshake, charge termination at 4.35V, and protection circuit response to overcurrent. The cell passed cutoff and recovery checks at both ends of the voltage window.
- Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard current. This lets the R17's fuel gauge IC map the new cell's discharge curve before VOOC pushes high current into an uncalibrated coulomb counter.
Sudden shutdown at 20–30% on the R17 after a cell replacement
This happens because the R17's fuel gauge IC is still using the discharge curve from the old, degraded cell. When the new cell hits a voltage point the old curve maps to 20–30%, the IC interprets it as critical and triggers shutdown — even though actual capacity remains. The fix is one full discharge to automatic cutoff followed by a full charge without interruption. After that cycle, the coulomb counter re-anchors to the new cell and percentage readouts stabilise.
VOOC fast charge not activating on the first cycle after fitting BLP681
The R17's VOOC handshake requires the charge IC to read cell impedance within an expected range before switching from standard 5V to the fast-charge voltage step. A brand-new cell has slightly higher impedance than a conditioned one, so the IC defaults to standard charging on the first cycle. Run one full charge at standard current — the charge IC will re-evaluate impedance at the start of the second cycle and VOOC will activate normally. If it still does not activate after two cycles, check the charge port for debris causing a contact fault.