O2 Xda Stealth Replacement Battery 3.7V 2800mAh XP-04

O2 Xda Stealth — 3.7V Li-Polymer Replacement Battery (XP-04)

This 3.7V 2800mAh Li-Polymer battery replaces the original cell in the O2 Xda Stealth PDA. It fits the Xda Stealth handheld computer running Windows Mobile, restoring power to applications, contacts, calendar, and email. OEM part numbers XP-04 and A2K40-STE090-ZOR both cross-reference to this cell.

• Xda Stealth platform fit: The Xda Stealth uses a single Li-Polymer cell on a 3.7V rail with a proprietary connector. This replacement matches that connector, cell geometry, and BMS handshake so the device recognises the battery without throwing a low-voltage warning on first boot.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Xda Stealth platform. The BMS responded correctly to the device's charge controller — no cutoff errors, no false full-charge flags.
• Sync before you swap: The Xda Stealth holds open application state and unsaved data in volatile RAM powered directly by the main battery. Before removing the old cell, perform a full ActiveSync or Windows Mobile Device Center sync to your PC. That flushes RAM-resident data to persistent storage and prevents loss during the swap.

Why the Xda Stealth loses contacts and calendar entries after a battery swap

Windows Mobile on the Xda Stealth keeps active data — open contacts, unsaved calendar entries, application state — in SRAM that the main battery powers continuously. The moment the battery is removed, that volatile memory loses power and the data is gone. There is no internal backup cell on this platform. A full sync to the host PC before the swap is the only way to protect that data.

Xda Stealth won't boot after installing a new battery

The Xda Stealth boot sequence requires the battery to present a minimum voltage before the device will initialise — a cell that ships partially discharged can fall below that threshold and the device simply shows a blank screen or does not respond to the power button. This is not a faulty battery. Connect the device to the wall charger and allow at least 20–30 minutes of charge before attempting the first boot. Once the cell reaches approximately 3.6V, the boot sequence will proceed normally.