Dopod DIAM171 S900c Replacement Battery 3.7V 2400mAh

Dopod S900c / Touch Pro — 3.7V Li-ion Replacement Battery (DIAM171)

This is a 3.7V, 2400mAh Li-ion cell built to the DIAM171 specification. It fits the Dopod S900c and Touch Pro Windows Mobile smartphones. It drops in with the original connector and BMS handshake, restoring power to both devices without modification.

• S900c and Touch Pro compatibility: Both devices run the same voltage rail and share the DIAM171 connector pinout. The BMS negotiation protocol is identical across the two platforms, so one cell covers both without any wiring changes.
• Bench tested on actual hardware: We ran this cell on the S900c under GSM modem load and full-screen brightness. The BMS held regulation through the high-draw cycles and did not trip the overcurrent cutoff during screen-on modem bursts.
• Fuel gauge recalibration on first use: After installing this cell, run one full discharge to device shutdown followed by an uninterrupted charge to 100%. The phone's fuel gauge IC was calibrated to the old cell's discharge curve. One complete cycle rewrites the coulomb counter baseline so percentage readings stay accurate.

Sudden shutdown at 20–30% on the S900c after a cell swap

This happens because the fuel gauge IC still uses the old cell's voltage-to-capacity curve. When the new cell hits a steeper voltage drop under modem or display load, the phone's low-voltage cutoff fires before the reported percentage reaches zero. The OS reads 25% right up until the cell voltage sags below the cutoff threshold. One full discharge-charge cycle forces the coulomb counter to remap against the actual discharge curve of the new cell.

Device won't power on after sitting in storage — BMS lockout

Li-ion cells self-discharge in storage. If the S900c sat unused for months, the cell voltage may have dropped below 2.5V per cell — the point where most BMS circuits lock out to prevent cell damage. The phone will show no response when you press the power button. Connect the device to a wall charger and leave it for 15–20 minutes before attempting to power on; the charge IC needs to trickle current into the cell until the BMS sees voltage above the recovery threshold, typically around 2.8–3.0V, before it will re-enable discharge.