About this replacement
Oppo R5 / R8107 / R8109 — 3.8V Li-Polymer Replacement Battery (BLP579)
The BLP579 is a 3.8V, 2000mAh lithium-polymer cell for the Oppo R5 smartphone and its R8107 and R8109 variants. At 2.90mm thick, the cell matches the R5's ultra-slim chassis — standard Li-ion cells will not fit this frame. This listing covers the direct swap for an original battery that no longer holds charge or causes unexpected shutdowns.
- R5, R8107, R8109 compatibility: All three model numbers share the same motherboard connector, BMS handshake protocol, and 2.90mm z-height constraint. The BLP579 part number covers the entire R5 family — there is no separate SKU for each variant.
- Bench tested on actual hardware: We cycled this cell through charge, load, and low-voltage cutoff on the R5 platform. The BMS accepted the cell without a forced reset, and the charge IC reached full termination voltage without fault flags.
- Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This gives the fuel gauge IC one complete curve to calibrate against the new cell before high-current charging begins on an uncalibrated reference.
Sudden shutdown at 20–30% on the replacement cell
The R5's fuel gauge IC carries the discharge curve from the old, degraded cell into the first few cycles with a new one. When the phone hits a point where the old curve predicted voltage collapse, it signals shutdown — even though the new cell has capacity left. This is a coulomb counter mismatch, not a faulty battery. One full uninterrupted discharge down to auto-off, followed by a full charge, resets the reference curve. After that cycle, shutdowns at 20–30% should stop.
Phone warm near the battery during the first charge after replacement
A new lithium-polymer cell has higher internal impedance than a cell that has been cycled. The charge IC on the R5 pushes current into that higher resistance, which generates more heat in the first one or two charge sessions. This is normal and typically resolves after two to three cycles as impedance drops. If the device stays warm past the third full charge, check that the connector is fully seated — a partially connected cell forces the charge IC to work harder against a resistive contact point.