O2 XDA Xphone II BTR5600B Replacement Battery 3.7V 2200mAh

O2 XDA Xphone II / Orion / IQ — 3.7V Li-ion Replacement Battery (BTR5600B)

This is a 3.7V Li-ion cell rated at 2200mAh (8.14Wh), built to replace the original BTR5600B in O2 XDA Xphone II, Xphone IIm, XDA Orion, and XDA IQ handsets. These devices share the same battery bay dimensions, connector pinout, and charge management circuit, so one cell covers the full model group. Swap out a degraded original and restore normal operation to the phone's display, processor, and radio stack.

• XDA Xphone II, Xphone IIm, Orion, and IQ compatibility: All four models run the same 3.7V battery rail, identical physical footprint, and use the same two-pin connector with matching polarity. The charge IC on each handset accepts this cell without any firmware intervention or hardware modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on XDA hardware, monitoring BMS cutoff thresholds at both the low-voltage floor and the 4.2V charge ceiling. The protection circuit tripped correctly at both limits, and the cell held voltage within spec across the full cycle.
• Fuel gauge recalibration on first use: After fitting this cell, disable any fast-charge accessory and run one full discharge-to-charge cycle at standard current. The fuel gauge IC in these handsets was calibrated to the original cell's discharge curve — one complete cycle at low current lets it re-anchor to the new cell before normal use resumes.

Sudden shutdown at 20–30% on the XDA Xphone II

This happens when the cell can no longer sustain voltage under peak load from the modem radio or backlit display. As the cell ages, its internal resistance rises. The voltage sags sharply the moment a high-draw event hits, dropping below the BMS cutoff threshold even though the fuel gauge still reads 20–30%. The phone sees a voltage cliff and shuts down to protect the circuit. A new cell with lower internal resistance holds voltage through those load spikes, and the shutdowns stop.

Phone will not power on after the battery sat in storage

Li-ion cells self-discharge during storage. If the cell drops below roughly 2.5V, the BMS enters lockout mode and blocks charge current entirely — the phone shows nothing when plugged in. To recover, connect the handset to a wall adapter rather than a USB port, since wall adapters deliver a steadier trickle current. Leave it connected for 20–30 minutes without pressing the power button. Once the cell climbs back above the BMS re-enable threshold (approximately 2.9V), normal charging resumes and the phone will power on.