Daxian Telecom CU928 Replacement Battery 3.7V 4200mAh

Daxian Telecom CU928 — 3.7V Li-ion Replacement Battery (PH26B)

This 3.7V, 4200mAh Li-ion battery replaces the OEM cell in the Daxian Telecom CU928 smartphone. It fits the original battery bay using the same connector and matches the PH26B and AHTXDSSN part numbers. Use it when the original cell no longer holds charge or causes unexpected shutdowns.

• Telecom CU928 fit: The CU928 uses a standardised 3.7V single-cell Li-ion rail. This replacement matches the voltage, physical footprint (84.78 × 58.32 × 11.68mm), and connector pinout so the phone's power management IC accepts the cell without triggering an incompatibility flag.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a CU928-class testbed. The BMS accepted the USB charge handshake cleanly and held voltage above the modem-load threshold throughout the discharge curve — no premature cutoff events recorded.
• Fuel gauge recalibration on first use: After installing this cell, disable fast charging and complete one full discharge-to-charge cycle at standard rate. The CU928's fuel gauge IC was calibrated against the old cell's discharge curve — one slow cycle lets it remap against this cell's actual capacity before fast current is applied.

Sudden shutdown at 20–30% on the Telecom CU928

This happens when the cell can no longer sustain voltage under peak load from the modem radio or display. The fuel gauge still reads 20–30% because it tracks charge coulombs, not live voltage — but the cell voltage collapses below the cutoff threshold the moment current demand spikes. A fresh cell with a correctly recalibrated fuel gauge eliminates this. After fitting the replacement, run the slow first-cycle recalibration so the fuel gauge IC tracks the new cell's actual voltage cliff point accurately.

Phone shows correct percentage one moment, then jumps erratically after a cell swap

The CU928's coulomb counter and fuel gauge IC retain calibration data from the previous cell. When a new cell is installed, those stored lookup values no longer match the new cell's discharge curve, so percentage readings skip forward or backward as the IC tries to reconcile live voltage against stale data. This settles after one complete charge-discharge cycle at standard (non-fast) charge rate. Once the IC has mapped a full cycle against the new cell, reported percentages stabilise — check that the phone reads 1% just before it shuts off and 100% only when charging stops cleanly.