Cricket SN304AE Replacement Battery BL-A40CT 3.85V 3900mAh

Cricket SN304AE / Innovate E 5G — 3.85V Li-Polymer Replacement Battery (BL-A40CT)

This is a 3900mAh (15.02Wh) Li-Polymer replacement cell for the Cricket SN304AE and Innovate E 5G smartphones. It matches the OEM part number BL-A40CT and fits the original battery bay without modification. Voltage is 3.85V nominal, matching the charge IC expectations on both models.

• SN304AE and Innovate E 5G compatibility: Both devices share the same BL-A40CT battery footprint, connector pinout, and BMS handshake protocol. The charge IC on each model reads the same NTC thermistor circuit, so the replacement cell communicates correctly with the system board without triggering protection faults.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the SN304AE platform. The BMS accepted the cell without entering lockout, and the coulomb counter logged expected capacity through the complete cycle. No thermal cutoff events occurred during CC/CV charge transition.
• Fuel gauge recalibration on first use: On first installation, disable fast charging and run one complete discharge-charge cycle at standard rate. The fuel gauge IC is still calibrated to the old cell's discharge curve — one full cycle at low current lets it remap the new cell before high-current fast charging pushes current into an uncalibrated state.

Why the SN304AE reports wrong battery percentage after a cell swap

The fuel gauge IC on this platform uses a coulomb counter algorithm that builds its reference model from the previous cell's charge and discharge history. When you install a new cell, that reference model is stale — it no longer matches the actual discharge curve of the fresh battery. The result is percentage readings that jump, stall, or land well above or below real capacity. One full discharge down to automatic shutdown, followed by a complete charge cycle at standard rate, forces the IC to rebuild its reference against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem radio or display triggers a high-current draw spike and the cell voltage drops sharply below the BMS low-voltage cutoff threshold — even though the gauge still shows charge remaining. The fuel gauge hasn't yet mapped the new cell's voltage sag behaviour under load, so it doesn't anticipate the cliff. After the first full calibration cycle, the IC learns where the voltage floor sits under peak load and adjusts the shutdown point accordingly. If shutdowns continue past two full cycles, check that the battery connector is fully seated — intermittent contact resistance amplifies voltage sag at the BMS sense line.