Samsung SGH-X495 Replacement Battery BST471ASA 3.7V 850mAh

Samsung SGH-X495 Series — 3.7V Li-ion Replacement Battery (BST471ASA)

This is a 3.7V, 850mAh Li-ion replacement cell for the Samsung SGH-X495 and related models. It fits the SGH-X495, SGH-X496, SGH-X497, and SGH-X909. Capacity is 850mAh (3.15Wh), matching the original BST471ASA specification.

• SGH-X495 / X496 / X497 / X909 compatibility: These models share the same BST471ASA footprint, connector pinout, and 3.7V nominal voltage rail. The BMS handshake on each device accepts the same cell chemistry, so one part number covers the full group.
• Bench tested on actual hardware: We cycled this cell on an SGH-X495 test unit and confirmed the BMS completed a full charge cycle without tripping a protection cutoff. Cell voltage held stable above 3.6V through the bulk charge phase.
• Fuel gauge recalibration on first cycle: After installing this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100%. The SGH-X495 fuel gauge IC maps its percentage readings against the cell's discharge curve on the first cycle — skipping this step causes the reported percentage to lag or jump for the first several days of use.

Why the SGH-X495 shuts down suddenly at 20–30% after a cell swap

The SGH-X495 uses a coulomb-counter fuel gauge calibrated to the original cell's internal resistance profile. A new cell has a different voltage-versus-capacity curve, so the gauge underestimates remaining charge and signals shutdown earlier than the cell is actually depleted. This is not a defective battery — it is a calibration mismatch. One full discharge-to-shutdown followed by an uninterrupted charge to 100% resets the reference curve. After that cycle, shutdowns at 20–30% stop in most cases.

Phone reports wrong battery percentage after replacement

The fuel gauge IC on the SGH-X495 stores a learned discharge model from the previous cell. When a new cell is fitted, the stored model no longer matches actual cell voltage, so the displayed percentage is inaccurate — often reading full charge then dropping sharply. The fix is one complete calibration cycle: drain the phone fully until it powers off on its own, then charge to 100% without interruption. After that single cycle, the IC rewrites its reference curve and percentage reporting stabilises.