Samsung SGH-U940 Replacement Battery AB603443EZ 3.7V 900mAh

Samsung SGH-U940 Glyde — 3.7V Li-ion Replacement Battery (AB603443EZBSTD)

This 3.7V 900mAh Li-ion cell replaces the original battery in the Samsung SGH-U940 and Glyde U940 flip phones. It matches the OEM voltage, capacity, and connector on both devices. Install it when your original cell no longer holds a charge or the phone shuts down unexpectedly.

• SGH-U940 and Glyde U940 compatibility: Both device variants use the same battery bay, connector pinout, and BMS handshake — the AB603443EZBSTD part number covers the full production run of that platform.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a U940 unit. The BMS accepted the cell without error flags, and the charge IC stepped through trickle, constant-current, and constant-voltage phases cleanly.
• Fuel gauge recalibration on first use: Run one full discharge-to-charge cycle before relying on the battery percentage indicator. The U940's fuel gauge IC is calibrated to the old cell's discharge curve — one complete cycle lets it map the new cell's voltage profile accurately.

Why the U940 reports wrong battery percentage after a cell swap

The U940 uses a fuel gauge IC that tracks capacity by counting charge flowing in and out of the cell. When you swap the cell, the IC still holds the old cell's discharge curve in memory. The percentage it reports is based on that stale reference — not the new cell's actual state. One full discharge followed by a full charge resets the reference point and brings the readout back in line with real charge levels.

Sudden shutdown at 20–30% on a replacement cell

This happens when the cell voltage drops sharply under load — the display backlight and radio draw current simultaneously and the cell cannot sustain voltage above the BMS cutoff threshold. The phone reads 25% but the cell's actual open-circuit voltage is already near 3.5V, which collapses further under peak draw. A replacement cell with a healthy internal resistance curve eliminates this sag. After installing, confirm the phone stays on through a full screen-on call — that is the highest combined load scenario on this hardware.