O2 XDA Cosmo EXCA160 Replacement Battery 3.7V 2200mAh

O2 XDA Cosmo — 3.7V Li-ion Replacement Battery (EXCA160)

This is a 3.7V Li-ion cell rated at 2200mAh (8.14Wh), built to replace the original battery in the O2 XDA Cosmo smartphone. It fits the Cosmo's battery bay directly and matches the OEM connector pinout for the BMS handshake. Part numbers EXCA160 and 35H00080-00M both cross-reference to this cell.

• XDA Cosmo fit: The Cosmo runs a single-cell Li-ion pack at 3.7V nominal. This replacement matches that voltage rail and the physical connector layout so the phone's charge IC and BMS can communicate correctly from first boot.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench, monitoring BMS cutoff behaviour at both ends of the voltage range. The protection circuit tripped correctly at low-voltage threshold and accepted a full charge without thermal events.
• Fuel gauge recalibration on first use: On first use after installation, run one complete discharge-to-charge cycle with fast charging disabled. This lets the fuel gauge IC map its reference curve against the new cell before normal charging resumes — skipping this step causes the phone to report inaccurate percentages for the first several cycles.

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

This happens because the fuel gauge IC is still using the discharge curve it mapped against the old, degraded cell. The new cell has a steeper voltage drop at the low end of its charge window. When the modem fires up or the screen backlight draws a spike, cell voltage dips below the BMS cutoff threshold even though the gauge still reads 20–30%. One full discharge-charge cycle on the new cell gives the coulomb counter the data it needs to recalculate state-of-charge accurately. After that cycle, shutdowns at apparent mid-charge levels stop.

O2 XDA Cosmo won't power on after sitting in a drawer

Li-ion cells that sit unused for months can drop below 2.5V per cell, which triggers a BMS lockout to prevent damage. The phone will show nothing — no charging animation, no response to the power button. Connect the device to a low-current USB charger and leave it for 15–20 minutes without pressing anything. Once the cell climbs back above the BMS recovery threshold (typically around 2.9–3.0V), the protection circuit releases and the phone will begin a normal charge cycle.