Samsung SCH-X319 Replacement Battery 3.7V 900mAh Li-ion

Samsung SCH-X319 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 900mAh (3.33Wh) lithium-ion battery for the Samsung SCH-X319 flip phone. It replaces the original cell when the existing battery no longer holds a usable charge. Fits the SCH-X319 and X319 variants.

• SCH-X319 platform fit: The X319 uses a fixed 3.7V single-cell Li-ion bay with a three-contact connector. Both the SCH-X319 and X319 share the same physical bay dimensions and voltage rail, so this cell fits both without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a representative 3.7V single-cell platform. The BMS accepted charge from a standard 4.2V Li-ion charger and engaged cutoff correctly at the low-voltage threshold.
• Fuel gauge recalibration on first use: On first installation, run one complete discharge-charge cycle with fast charging disabled. The fuel gauge IC on the X319 calibrates its internal model against the cell's actual discharge curve — skipping this step leads to inaccurate percentage readings until the IC catches up.

Sudden shutdown at 20–30% on the replacement cell

The X319's fuel gauge IC retains the discharge curve from the old, degraded cell. A new cell has a steeper voltage cliff at lower states of charge than the worn cell the IC was tracking. When the phone draws current for a call or keypad backlight, voltage dips sharply at that uncalibrated threshold and the protection circuit interprets it as a undervoltage event. One full discharge-charge cycle — draining to auto-shutdown, then charging uninterrupted to 100% — resets the IC's reference curve and eliminates the false cutoff.

Phone won't power on after battery sat in storage

Li-ion cells discharged below roughly 2.5V trigger the BMS lockout, which blocks normal charging to prevent thermal runaway on a deeply depleted cell. A charger that starts at full current will be refused. To recover, connect the phone to a low-current USB source — a PC port rather than a wall adapter — and leave it untouched for 15–20 minutes. This allows the BMS to accept a trickle pre-charge that brings cell voltage back above the 2.9V re-enable threshold before normal charging resumes.