AT&T Fuze DIAM171 Replacement Battery 3.7V 2400mAh

AT&T Fuze — 3.7V Li-ion Replacement Battery (DIAM171)

This 3.7V, 2400mAh Li-ion cell is a direct replacement for the AT&T Fuze smartphone. The Fuze is a Windows Mobile business phone with a slide-out QWERTY keyboard, released in 2008. It draws on a single Li-ion cell rated at 8.88Wh, matching the original DIAM171 spec.

• Fuze platform fit: The Fuze shares its battery footprint with HTC Touch Pro hardware — same 41.96 x 40.82 x 15.75mm cavity, same three-contact connector, same BMS handshake expected by the Windows Mobile power management stack. OEM part numbers DIAM171, 35H00111-08M, and 35H00111-06M all map to this cell.
• Bench tested on actual hardware: We ran this cell through a full charge cycle on the Fuze platform and confirmed the BMS handshake cleared without error. The charge IC accepted the cell and terminated at the correct cutoff voltage without throttling or fault flags.
• Fuel gauge recalibration on first use: On first use after installation, disable any fast-charge accessory and run one complete discharge-to-charge cycle. The Fuze fuel gauge IC calibrates against the cell's discharge curve — skipping this step leaves the coulomb counter reading against old cell data, which causes inaccurate percentage reporting from the first charge onward.

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

The Fuze's modem radio and backlit keyboard draw current in short, high-intensity bursts. A new cell with an uncalibrated fuel gauge IC can report 25% remaining while the actual cell voltage has already dropped to the BMS cutoff threshold under that load. The BMS trips and the phone shuts down — not because the cell is faulty, but because the gauge hasn't mapped the new cell's voltage-to-capacity curve yet. Run one full discharge to auto-shutoff, then charge uninterrupted to 100%, and the fuel gauge IC will recalibrate. After that cycle, shutdowns at false-high percentages should stop.

Phone shows wrong battery percentage after installing replacement cell

Windows Mobile on the Fuze stores the previous cell's discharge curve in the fuel gauge IC. When a new 2400mAh cell goes in, the IC is still referencing the old degraded cell's profile — so the percentage readout is wrong from the moment you boot up. This is a calibration mismatch, not a cell defect. Drain the phone fully until it powers off on its own, then charge to 100% without interruption. The fuel gauge IC writes a new curve after that first complete cycle and percentage accuracy returns to normal.