Coolpad Cool 1 CPLD-403 Replacement Battery 3.85V 3900mAh

Coolpad Cool 1 / C106 — 3.85V Li-Polymer Replacement Battery (CPLD-403)

This is a 3.85V, 3900mAh Li-Polymer replacement battery for the Coolpad Cool 1 and C106 smartphones. It replaces OEM part number CPLD-403. Fit this battery when the original cell can no longer hold a consistent charge or shuts the phone down unexpectedly under load.

• Cool 1 and C106 compatibility: Both models run the same CPLD-403 cell with identical connector pinout, voltage rail, and BMS handshake. The same physical dimensions — 80.60 x 62.10 x 4.44mm — mean no case stress or flex cable tension on installation.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a Cool 1 unit. The BMS accepted charge from both standard and fast-charge adapters. Voltage held at 3.85V nominal with no thermal events during cycling.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging for the first complete discharge-charge cycle. This gives the fuel gauge IC time to map its coulomb counter against the new cell's discharge curve before high-current charging begins on an uncalibrated cell.

Sudden shutdown at 20–30% on the Cool 1 after a cell swap

The Cool 1's fuel gauge IC retains the discharge curve of the old, degraded cell after replacement. When a fresh cell hits the voltage range the IC previously associated with a low or failing cell, it signals a forced shutdown. This is not a fault with the new battery — it is a calibration mismatch. One full discharge down to auto-off, followed by an uninterrupted charge to 100%, resets the IC's reference curve and corrects the cutoff point.

Fast charging not recognised on the first cycle after replacement

On the first charge cycle after fitting a new CPLD-403, the charge IC may fall back to standard 5V charging and ignore the fast-charge handshake. This happens because the BMS on a new cell starts in a conservative state until it confirms a complete charge cycle without fault. Let the first charge complete fully at standard rate. Fast charge protocol should resume normally from the second cycle onward without any further intervention.