O2 Xda Diamond 2 Replacement Battery TOPA160 3.7V 2200mAh

O2 Xda Diamond 2 — 3.7V Li-ion 2200mAh Replacement Battery (TOPA160)

This is a 3.7V Li-ion battery rated at 2200mAh (8.14Wh), built to fit the O2 Xda Diamond 2 and Xda Diamond II smartphones. It replaces OEM part numbers TOPA160, 35H00125-07M, and BA S360. If your original cell is swelling, failing to hold charge, or triggering unexpected shutdowns, this is a direct swap.

• Xda Diamond 2 and Diamond II compatibility: Both the Diamond 2 and Diamond II share the same battery bay dimensions, connector pinout, and BMS handshake protocol — that is why both model names appear on this listing. The cell measures 65.04 × 40.29 × 8.68mm, matching the factory recess exactly.
• Bench tested on actual hardware: We ran this battery through charge and discharge cycles on a Diamond 2 unit. The BMS accepted the cell without error flags, and the protection circuit tripped correctly at the low-voltage threshold, as expected on a healthy Li-ion pack.
• 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. This allows the fuel gauge IC to map its coulomb counter against the new cell's discharge curve before high-current charging begins on an uncalibrated reference.

Sudden shutdown at 20–30% on the Xda Diamond 2

This happens when the cell can no longer sustain voltage under modem or display load — it sags below the cutoff threshold even though the reported percentage looks safe. On an aged original cell, the internal resistance climbs high enough that any spike in current draw collapses the terminal voltage instantly. A new cell with lower internal resistance handles those spikes without dropping into shutdown territory. After fitting the replacement, one full discharge cycle lets the fuel gauge IC reset its low-voltage cliff calculation to the new cell's actual curve.

Phone shows incorrect battery percentage after cell replacement

The Xda Diamond 2 uses a fuel gauge IC that stores a learned discharge profile from the previous cell. When you install a new 2200mAh cell, that stored profile no longer matches — the IC reports percentage against the old curve, not the new one. This causes readings that jump, plateau early, or show 100% after only a partial charge. Fix it by draining the phone to automatic shutdown, then charging uninterrupted to 100% — one complete cycle resets the coulomb counter reference to 3.7V nominal on the new cell.