BLP619 Oppo A57 Replacement Battery 3.85V 2800mAh Li-Polymer

Oppo A57 Series — 3.85V Li-Polymer Replacement Battery (BLP619)

The BLP619 is a 3.85V, 2800mAh Li-Polymer cell that fits the Oppo A57, A57 Dual SIM, A57 Dual SIM TD-LTE, A57t, and several additional A57 variants. It replaces a dead or degraded original cell and restores full device function. Capacity figure is 10.78Wh at the rated voltage.

• A57 variant compatibility: All A57 models in this family share the same PCB footprint, connector pitch, and 3.85V nominal voltage rail, so one cell covers the full range without BMS handshake conflicts.
• Bench tested on actual hardware: We cycled BLP619 cells through charge and load on the A57 platform. The BMS accepted charge current correctly, held voltage within spec under sustained screen and modem load, and triggered protection cutoff cleanly at the low-voltage threshold.
• Fuel gauge recalibration after install: On first use after fitting this cell, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated cell.

Sudden shutdown at 20–30% on the A57 after a cell swap

This is a voltage cliff problem, not a defective cell. The fuel gauge IC is still running the discharge curve it learned from the old, degraded cell. When the new cell hits a voltage point the IC associates with near-empty, it signals shutdown — even though the cell has capacity left. The fix is one full uninterrupted discharge down to automatic power-off, followed by a full charge to 100%. After that cycle, the fuel gauge recalibrates its curve to the new cell and the early shutdowns stop.

A57 not powering on after the replacement battery sat in storage

Li-Polymer cells ship with a partial charge, but if the battery sat in storage for an extended period, the cell voltage may have dropped below 2.5V — the BMS hard lockout threshold. At that level, the BMS disconnects the cell to prevent damage and the phone will not respond to the power button or a standard charger. Connect the phone to a low-output USB charger (5V/0.5A) and leave it for 20–30 minutes. This trickle current is enough to bring the cell above the lockout threshold, after which the BMS reconnects and normal charging resumes. Check that the charging LED activates within 30 minutes; if it does not, the cell has gone below the recovery threshold of approximately 2.4V.