Uniscope U73 Replacement Battery 3.7V 750mAh

Uniscope U73 — 3.7V Li-ion Replacement Battery (U73)

This is a 3.7V, 750mAh Li-ion replacement battery for the Uniscope U73 smartphone. It fits directly into the U73 and restores power to a phone whose original cell has degraded or failed. Capacity is 2.78Wh as rated.

• Uniscope U73 fit: The U73 uses a single-cell 3.7V nominal Li-ion pack with a compact 53.00 x 33.90 x 5.70mm footprint. The connector pinout and BMS handshake match the original — the phone's charge IC communicates with the pack on the same data line as the factory cell.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the U73 platform. The BMS held low-voltage cutoff correctly and the charge IC accepted the pack without throwing a fault or refusing to initiate the charge cycle.
• Fuel gauge recalibration after install: On first use after fitting this cell, disable fast charging if available and run one full discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC one complete reference cycle against the new cell's discharge curve before it starts reporting percentages to the OS.

Why the U73 reports wrong battery percentage after a cell swap

The fuel gauge IC on the U73 builds its percentage model from the discharge curve of the original cell. When you fit a new cell, that learned curve no longer matches reality. The IC interpolates voltage against an old map, so the displayed percentage drifts from actual state of charge. One full uninterrupted discharge-to-shutdown followed by a full charge resets the coulomb counter reference and brings the readout back into alignment.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops below what the phone's processor and modem need to sustain a load spike — even though the displayed percentage looks safe. A new cell with an uncalibrated fuel gauge can show 25% while actual cell voltage is already near the cutoff threshold under screen or modem draw. The BMS trips before the OS has time to initiate a graceful shutdown. Run the full calibration cycle first — one complete discharge to cutoff, then charge to 100% — and the shutdowns stop once the IC maps the new cell's voltage floor accurately.