BL4247 Fly IQ442 Replacement Battery 3.7V 1500mAh

Fly IQ442 — 3.7V Li-ion Replacement Battery (BL4247)

This is a 3.7V, 1500mAh Li-ion replacement battery for the Fly IQ442 smartphone. It replaces OEM part BL4247 and fits the IQ442 directly. Capacity is 1500mAh (5.55Wh) — matching the original cell specification.

• IQ442 fitment: The BL4247 footprint is specific to the IQ442 — 55.90 x 53.80 x 5.06mm. The connector and cell dimensions match the original bay. No third-party adapters or modifications required.
• Bench tested on actual hardware: We cycled this battery through full charge and discharge on the IQ442 platform. The BMS accepted the charge IC handshake on the first cycle. Voltage held stable under simultaneous modem and display load.
• Fuel gauge recalibration on first cycle: After fitting, disable fast charging if your IQ442 supports it and run one complete discharge-charge cycle before normal use. The fuel gauge IC on the IQ442 is calibrated to the old cell's discharge curve. One full cycle lets it map the new cell's voltage profile before reporting accurate percentages.

Sudden shutdown at 20–30% on the IQ442 after a cell swap

A new Li-ion cell has a slightly different voltage-versus-capacity curve than the worn cell it replaces. The IQ442's fuel gauge IC still references the old curve, so it can misread remaining capacity by a significant margin. When the modem transmits or the display runs at full brightness, current draw spikes — and the new cell's actual voltage drops below the cutoff threshold before the gauge expects it. The phone shuts down even though the reported percentage looks safe. One full discharge-charge cycle corrects the gauge mapping and eliminates most unexpected shutoffs.

IQ442 percentage jumping erratically after replacement

Erratic percentage readings — jumping from 45% to 60% or dropping suddenly — point to a coulomb counter that is still running the previous cell's calibration data. The fuel gauge IC accumulated correction factors for the old degraded cell and is now applying them to a new cell with different internal resistance. This is not a fault with the replacement battery. Discharge the phone until it powers off automatically, then charge uninterrupted to 100% — this forces a full recalibration cycle and stabilises the reported percentage.