AT&T Atrix 2 HW4X Replacement Battery 3.7V 1700mAh

AT&T Motorola Atrix 2 — 3.7V Li-ion Replacement Battery (HW4X / SNN5892A)

This is a 3.7V, 1700mAh Li-ion cell for the AT&T Motorola Atrix 2 smartphone. It replaces OEM part numbers HW4X, SNN5892, and SNN5892A. Swap it in when the original cell no longer holds a full charge or the phone shuts down unexpectedly under load.

• Atrix 2 compatibility: The Atrix 2 uses a fixed 3.7V single-cell architecture with a BMS that monitors charge termination via a dedicated fuel gauge IC. This cell matches that voltage rail and communicates with the onboard coulomb counter correctly.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Atrix 2 platform. The BMS accepted the cell without fault flags, and the charge IC reached full termination voltage without thermal events.
• Fuel gauge recalibration on first install: After fitting this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before enabling fast charge. This lets the fuel gauge IC map the new cell's discharge curve before high-current cycles begin.

Why the Atrix 2 reports wrong battery percentage after a cell swap

The Atrix 2 fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches actual cell behaviour, so the percentage readout drifts. The fix is one full discharge-to-shutdown followed by an uninterrupted charge to 100%. After that cycle, the coulomb counter recalibrates against the new cell's actual capacity and the percentage readout stabilises.

Sudden shutdown at 20–30% remaining on the replacement cell

This happens when the cell voltage drops below the modem or display's minimum threshold under load, even though the fuel gauge still shows charge remaining. The old calibration data tells the OS the battery has more headroom than it does. A full discharge-recharge cycle resets the low-voltage cliff estimate in the fuel gauge IC. If shutdowns persist after two full cycles, check that the battery connector is fully seated — a loose contact raises contact resistance and accelerates voltage sag under load.