SmartFren Andromax i2 BL-4P-I Replacement Battery 3.7V 1800mAh

SmartFren Andromax i2 — 3.7V Li-ion Replacement Battery (BL-4P-I)

This is a 3.7V, 1800mAh Li-ion replacement battery for the SmartFren Andromax i2 (AD683J). It replaces OEM part number BL-4P-I. Swap it in when the original cell can no longer hold charge or the phone shuts down unexpectedly under load.

• Andromax i2 and AD683J compatibility: Both model designations — Andromax i2 and AD683J — use the same BL-4P-I cell form factor, voltage rail, and connector pin-out. The BMS handshake matches what the charge IC on this board expects, so the phone accepts the cell without error flags.
• Bench tested on actual hardware: We cycled this cell on an Andromax i2 board and monitored BMS communication throughout charge and discharge. The protection circuit engaged correctly at the low-voltage cutoff, and the charge IC completed a full CC-CV cycle without interruption.
• Fuel gauge recalibration on first install: After fitting this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100% before using fast-charge features. The Andromax i2 fuel gauge IC needs one full reference cycle against the new cell's discharge curve — skipping this causes the percentage counter to drift or report early cutoff.

Sudden shutdown at 20–30% on the Andromax i2 after a cell swap

This is a voltage-cliff problem, not a capacity problem. The Andromax i2's modem and display draw a combined current spike that the new cell's internal impedance cannot sustain at lower state-of-charge, causing the cell voltage to sag below the BMS cutoff threshold even though the fuel gauge still shows charge remaining. The phone cuts out to protect the cell. One full calibration cycle — discharge to shutdown, then a complete uninterrupted charge — teaches the fuel gauge IC where the real voltage floor sits on this specific cell, and the shutdowns stop.

Phone feels warm near the battery compartment on the first few charges

A new high-impedance cell dissipates slightly more heat during the constant-current phase than the worn cell it replaced. The charge IC on the Andromax i2 holds its programmed charge current regardless, so the cell runs warmer until internal resistance settles after two or three cycles. This is not a fault. If the phone becomes hot to the touch — not just warm — or the charge IC throws an error and stops charging before 100%, remove the battery and let it cool to room temperature before continuing. After the first three full cycles, surface temperature during charging should return to normal.