Coolpad 8809 CPLD-69 Replacement Battery 3.7V 1700mAh

Coolpad 8809 — 3.7V Li-ion Replacement Battery (CPLD-69)

This is a 3.7V Li-ion battery rated at 1700mAh (6.29Wh), built to the CPLD-69 spec for the Coolpad 8809 smartphone. It replaces the original cell when the phone no longer holds charge, shuts down unexpectedly, or won't power on. The connector and BMS pinout match the 8809 motherboard directly.

• Coolpad 8809 fit: The 8809 uses a fixed 3.7V rail tied to its baseband processor and display driver. Any replacement cell must match this voltage and the CPLD-69 BMS handshake — a mismatch here causes the charge IC to reject the pack entirely.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the 8809 platform. The BMS responded correctly at both charge cutoff (4.2V) and low-voltage protection (2.5V), with no thermal events or rejected handshakes.
• Fuel gauge recalibration on first use: After installing this cell, disable any fast-charge mode and complete one full discharge-charge cycle before normal use. This gives the 8809's fuel gauge IC time to map the new cell's discharge curve — skipping this step causes the percentage readout to drift or jump erratically for the first several cycles.

Why the Coolpad 8809 reports wrong battery percentage after a cell swap

The 8809 uses a coulomb counter in the fuel gauge IC that builds its percentage model against the original cell's discharge curve. When you install a new cell, that learned curve no longer matches. The IC continues using old calibration data, so the percentage you see on screen diverges from actual charge state. One full discharge to auto-shutoff followed by a complete charge to 100% forces the IC to relearn against the new cell and restores accurate readouts.

Coolpad 8809 shutting down suddenly at 20–30% remaining

This happens when the cell voltage drops sharply under the combined load of the modem radio and display — a voltage cliff the fuel gauge did not predict. An aged or degraded original cell loses its ability to sustain voltage under peak draw, so the BMS trips the low-voltage cutoff before the percentage reaches zero. Replacing the cell with a fresh CPLD-69 unit eliminates the sag. After replacement, confirm the cell rests at or above 3.7V open-circuit before the first charge cycle.