Qtek 9100 WIZA16 Replacement Battery 3.7V 2800mAh

Qtek 9100 — 3.7V Li-ion Replacement Battery (WIZA16)

This 3.7V 2800mAh Li-ion battery is a direct cell replacement for the Qtek 9100 Windows Mobile smartphone. It matches the OEM voltage rail and physical footprint — 51.86 x 38.97 x 12.48mm — so it seats correctly in the battery bay. Capacity listed here comes from the product data, not a third-party estimate.

• Qtek 9100 platform fit: The 9100 shares its battery bay and connector with select HTC Windows Mobile handsets from the same era. OEM cross-references WIZA16, 35H00062-00M, and HTC098347 all map to the same cell specification, same connector pinout, and same BMS handshake requirement.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the 9100 platform. The BMS accepted the charge IC handshake without fault codes, and the cell voltage held above 3.5V under screen-on and radio-active load.
• Fuel gauge recalibration after installation: On first use, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before using the device. This gives the fuel gauge IC a full reference curve against the new cell — without it, percentage readings will drift immediately after installation.

Why the Qtek 9100 reports wrong battery percentage after a cell swap

The 9100 uses a coulomb-counting fuel gauge IC that builds its charge model from accumulated cycle data stored against the original cell. When a new cell goes in, that stored model no longer matches the actual discharge curve of the replacement. The gauge reads percentage against the old curve, so it can show 40% while the cell is already near cutoff voltage. One full discharge-charge cycle — letting the device shut down naturally, then charging to 100% uninterrupted — forces the IC to reset its reference points. After that cycle, percentage accuracy stabilises.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff failure, not a capacity problem. When the modem transmits or the screen brightness peaks, current draw spikes sharply. If the cell voltage cannot hold above the BMS cutoff threshold — typically 3.0V under load — the BMS trips and the phone cuts out instantly, even though the gauge still shows charge remaining. A new cell that has not completed its first full calibration cycle is especially prone to this because the gauge is feeding the BMS inaccurate state-of-charge data. Run that first full discharge cycle, confirm the cell reaches at least 4.1V at full charge, and the shutdowns will stop.