Qtek 8500 Replacement Battery STAR160 3.7V 850mAh

Qtek 8500 / 8500 Pink — 3.7V Li-ion Replacement Battery (STAR160)

This 3.7V 850mAh Li-ion cell replaces the STAR160 battery in the Qtek 8500 and 8500 Pink smartphones. Both devices share the same battery bay dimensions and connector, making this a direct cell match at 44.97 × 37.16 × 5.44mm. Capacity is 850mAh (3.15Wh) — identical to the original specification.

• 8500 and 8500 Pink compatibility: Both variants use the same battery housing, connector pinout, and charge IC handshake. The STAR160 part number covers the full model run without hardware modification.
• Bench tested on actual hardware: We cycled this cell through charge, standby, and screen-on load. The BMS held voltage above the 3.0V cutoff under sustained screen draw and accepted charge termination cleanly at 4.2V.
• Fuel gauge recalibration on first use: On first use after installation, run one full discharge to automatic cutoff, then charge uninterrupted to 100% before normal use. The Qtek 8500's fuel gauge IC maps its coulomb counter to the new cell's discharge curve during this cycle — skipping it causes erratic percentage readings from the first hour.

Sudden shutdown at 20–30% on the Qtek 8500

This is a voltage-cliff failure, not a capacity failure. The Windows Mobile power manager on the 8500 uses a voltage threshold — not a true coulomb count — to estimate remaining charge. When the cell voltage sags under modem radio or screen load, it drops below the shutdown threshold even though the fuel gauge still reads 20–30%. A replacement cell showing this behaviour needs one full calibration cycle. Discharge to automatic cutoff, charge to 4.2V, and the fuel gauge IC will remap its threshold curve to the new cell.

Phone feels warm near the battery slot on the first few charges

A new high-impedance cell generates more heat during early charge cycles than a worn-in cell does. The charge IC on the Qtek 8500 does not throttle current based on cell impedance — it runs its standard CC/CV profile regardless. This warmth is normal for the first two or three cycles as internal resistance drops. If the device remains warm beyond the third full charge, check that the cell is seated flat with no gap at the contact plate — poor contact forces the charge IC to compensate with higher voltage, which increases heat.