Fly IQ434 Replacement Battery BL6412 3.7V 800mAh

Fly IQ434 Era Nano 5 — 3.7V Li-ion Replacement Battery (BL6412)

This is a 3.7V, 800mAh Li-ion cell sourced to match the OEM BL6412 specification. It fits the Fly IQ434 and Era Nano 5 smartphones. Voltage and connector pinout match the original so the phone powers on without hardware modification.

• IQ434 and Era Nano 5 compatibility: Both models run on the same 3.7V single-cell rail with the same BL6412 connector footprint and BMS handshake. One cell covers both variants without any adapter or wiring change.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the IQ434 platform. The BMS accepted charge from the onboard charge IC without a fault flag, and the fuel gauge IC tracked state of charge through a full discharge without dropping into error mode.
• Fuel gauge recalibration on first use: On first use after installation, run one complete discharge-to-charge cycle without interruption. The Era Nano 5's fuel gauge IC carries calibration data from the old cell curve — one full cycle rewrites that baseline against the new cell so percentage readings are accurate from cycle two onward.

Why the IQ434 reports wrong battery percentage after a cell swap

The IQ434 uses a fuel gauge IC that builds a discharge curve from the cell it was calibrated against. When a new cell goes in, the IC still references the old curve, so the percentage display is off until it relearns. The fix is straightforward: let the phone drain to automatic shutoff, then charge uninterrupted to 100% with the screen idle. After that single cycle, the IC recalculates its coulomb count against the new cell's actual capacity and the readout stabilises.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below what the modem or display backlight needs under load, even though the fuel gauge still shows charge remaining. The IQ434's modem draws a short current spike during calls and data activity — if the cell's internal resistance is slightly higher than the original, voltage sags enough to trip the low-voltage cutoff. Check the shutdown voltage in the device logs; if it's cutting off above 3.4V under load, run two more full calibration cycles. Most users see the issue resolve by cycle three as the BMS and fuel gauge IC align on the new cell's real discharge floor.