Asus ZenFone 5 A502CG Replacement Battery 3.8V 2500mAh

Asus ZenFone 5 A502CG — 3.8V Li-Polymer Replacement Battery (C11P1410)

This is a 3.8V 2500mAh (9.5Wh) lithium-polymer replacement battery for the Asus ZenFone 5 A502CG and ZenFone 5 Lite. It replaces OEM part numbers C11P1410 and 0B200-01210100. If your original cell has degraded after repeated charge cycles, this cell restores full capacity to your device.

• ZenFone 5 A502CG and 5 Lite compatibility: Both models run the same 3.8V single-cell Li-Polymer architecture with an identical connector pinout and BMS handshake profile. One replacement cell covers both variants without modification.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the ZenFone 5 platform. The BMS accepted the cell without fault flags, and the charge IC stepped through CC/CV phases normally with no thermal events.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes into an uncalibrated state — which is what causes erratic percentage readings post-swap.

Sudden shutdown at 20–30% on the ZenFone 5 A502CG after a cell swap

This shutdown pattern is a voltage cliff, not a calibration glitch. A degraded original cell holds voltage under light load but collapses when the modem, display, or GPS pulls a sustained current spike. The fuel gauge reports 25% because it's reading open-circuit voltage — not the loaded voltage the SoC actually sees. After fitting the new cell, run one full discharge cycle without fast charging so the coulomb counter resets its baseline to the new cell's actual capacity curve.

Device won't power on after the replacement cell sat in storage

Li-Polymer cells self-discharge in storage, and if the cell voltage drops below approximately 2.5V per cell, the BMS trips into lockout mode to prevent damage. The phone shows nothing — no charging animation, no boot screen. Connect the device to a wall charger (not a USB hub) and leave it for 20–30 minutes without pressing the power button. Once the BMS detects voltage climbing above its recovery threshold, typically around 2.8–3.0V, it re-initialises and normal charging resumes.