Asus ZenFone 4 PF400CG Replacement Battery C11P1404 3.7V 1150mAh

Asus ZenFone 4 PF400CG / A400CG — 3.7V Li-ion Replacement Battery (C11P1404)

This is a 3.7V, 1150mAh Li-ion cell built to the C11P1404 specification for the Asus ZenFone 4 PF400CG and A400CG. It replaces the original battery when the phone no longer holds a charge, shuts down unexpectedly, or won't power on at all. Voltage and capacity match the original cell exactly.

• PF400CG and A400CG compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The C11P1404 part number covers both variants — one cell fits either board without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a ZenFone 4 board. The BMS accepted the cell without fault flags, and the fuel gauge IC tracked state-of-charge correctly after one full calibration cycle.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one complete discharge down to automatic shutdown, then charge to 100% uninterrupted. This lets the fuel gauge IC map its reference curve to the new cell before high-current charging begins on an uncalibrated state-of-charge reading.

Sudden shutdown at 20–30% on the ZenFone 4 after a cell swap

This happens because the fuel gauge IC still holds the discharge curve from the old, degraded cell. The new cell has a steeper voltage response under modem and screen load, so the phone hits the low-voltage cutoff threshold earlier than the percentage readout predicts. The phone reports 25% but the cell voltage has already dropped below the safe floor under load. One full discharge-charge cycle forces the coulomb counter to relearn the new cell's curve and eliminates the early cutoff.

Phone not powering on after the replacement cell sat in storage

Li-ion cells self-discharge during storage. If voltage has dropped below approximately 2.5V per cell, the BMS enters a lockout state and refuses to allow charge current through. The phone shows nothing on screen — no charging animation, no logo. Connect to a charger and leave it for 15–20 minutes without pressing the power button; the charge IC will trickle current into the cell at a reduced rate until voltage recovers above the BMS re-enable threshold, typically around 3.0V, at which point normal charging resumes.