MyPhone A919i Dual Replacement Battery 3.7V 2000mAh Li-ion

MyPhone A919i Dual — 3.7V Li-ion Replacement Battery

This is a 3.7V, 2000mAh (7.4Wh) Li-ion cell built to fit the MyPhone A919i Dual smartphone. It slots into the original battery bay and connects to the phone's charge IC and fuel gauge circuit. Use it when the stock cell no longer holds enough charge to get through a day of calls, messaging, and app use.

• A919i Dual fit: The A919i Dual runs a dual-SIM radio stack, which draws more standby current than single-SIM phones. This cell matches the original 3.7V nominal voltage and 2000mAh capacity that the phone's BMS expects — keeping charge termination and low-voltage cutoff thresholds in spec.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the A919i Dual platform. The BMS accepted charge termination correctly, and the fuel gauge IC tracked state-of-charge without triggering early cutoff or overcharge flags.
• First-cycle fuel gauge recalibration: After fitting this cell, disable fast charging if available and run one full discharge-to-charge cycle before normal use. The fuel gauge IC carries calibration data from the old cell — one complete cycle lets it map the new discharge curve accurately before high-current charging begins.

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

This happens because the fuel gauge IC is still running the old cell's voltage-to-capacity curve. When the new cell hits a voltage point the IC wasn't expecting, it misreads remaining charge and cuts power to protect the phone. The modem radio in the dual-SIM stack draws a sharp current spike during active calls, which accelerates the voltage drop below the cutoff threshold. One full discharge cycle — draining to auto-off and charging uninterrupted to 100% — resets the coulomb counter against the new cell's actual curve.

Battery percentage jumping erratically after replacement

Erratic percentage readings after a cell swap are a fuel gauge IC calibration issue, not a faulty battery. The IC was tuned to the internal resistance and discharge profile of the worn-out original cell — the new cell behaves differently under load, so the reported percentage jumps. Run two complete charge cycles without interrupting charging partway through. After the second full cycle, the coulomb counter recalibrates and percentage reporting stabilises.