Qtek 9090 Replacement Battery PH26B 3.7V 4200mAh

Qtek 9090 / 9060 — 3.7V Li-ion Replacement Battery (PH26B)

This 3.7V, 4200mAh Li-ion cell replaces the OEM battery in the Qtek 9090 and 9060 smartphones. It matches the original PH26B (also listed as AHTXDSSN) specification and fits the existing battery bay without modification. Capacity is rated at 15.54Wh.

• 9090 and 9060 compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS communication protocol — that is why one cell covers both. The 84.78 × 58.32 × 11.68mm footprint matches the original housing exactly.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a 9090 unit, confirmed BMS handshake on both charge and discharge rails, and verified the protection circuit triggers correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: After fitting, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the phone's fuel gauge IC build an accurate discharge curve against the new cell before high-current charging is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the Qtek 9090 after a cell swap

The 9090's fuel gauge IC retains the discharge curve it learned from the original cell. When a new cell with a different internal resistance is installed, the IC misreads the remaining voltage and triggers an early shutdown before the cell is actually depleted. This is not a fault with the replacement cell — it is a calibration mismatch. Run two full discharge-charge cycles at standard charge rate to let the coulomb counter reset against the new cell's actual curve. After those cycles, the reported percentage should track true state of charge consistently.

Phone not powering on after the new battery sat in storage

Li-ion cells shipped in storage state can drop below the BMS reactivation threshold — typically 2.5V per cell — if they sit unused for several months. When voltage falls that low, the BMS locks the discharge path to prevent cell damage, and the phone shows no sign of life. Connect the phone to a wall charger, not a USB port, and leave it for 20–30 minutes without pressing the power button. Once the charger pushes enough current to lift cell voltage above the BMS unlock threshold, the phone will boot normally. If there is still no response after 30 minutes, check that the charger output is at least 5V 1A.