MyPhone A919i Dual Replacement Battery 3.7V 1700mAh Li-ion

MyPhone A919i Dual — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1700mAh Li-ion replacement battery for the MyPhone A919i Dual smartphone. It fits directly into the A919i Dual battery compartment and restores power to a phone that no longer holds a charge. Capacity is 6.29Wh.

• A919i Dual compatibility: The A919i Dual runs a dual-SIM radio stack, which draws simultaneous current from two baseband modules. This cell matches the voltage rail and physical footprint the phone's charge IC expects — wrong cell impedance here causes erratic shutdowns under dual-SIM load.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a smartphone test rig. The BMS accepted charge current without tripping, held voltage above 3.5V through mid-discharge, and reported state-of-charge to the fuel gauge IC without error flags.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before the charge IC applies high-current charging to an uncalibrated cell.

Sudden shutdown at 20–30% on the A919i Dual after a cell swap

The A919i Dual's fuel gauge IC retains the discharge curve from the old cell after a swap. When the new cell hits its voltage cliff — typically around 3.55–3.6V under dual-SIM or screen load — the phone cuts out even though the gauge still shows 20–30% remaining. This is a calibration mismatch, not a faulty battery. One full discharge cycle from 100% to auto-shutdown, followed by an uninterrupted charge to 100%, resets the coulomb counter to the new cell's curve.

Phone not powering on after the replacement battery sat in storage

Li-ion cells self-discharge during storage, and if the cell drops below 2.5V the BMS enters lockout to prevent damage — the phone will show nothing when you press the power button. Connect the phone to a wall charger, not a USB port, and leave it for 15–20 minutes before attempting to power on. The charge IC needs enough current to push the cell back above the BMS re-enable threshold, which is typically 2.9–3.0V. Once the phone shows a charging indicator, the BMS has reset and normal charging can resume.