HTC Iris BERR160 Replacement Battery 3.7V 1250mAh

HTC Iris / S640 Series — 3.7V Li-Polymer Replacement Battery (BERR160)

This is a 3.7V, 1250mAh Li-Polymer cell for the HTC Iris, Iris 100, and S640. It replaces OEM part numbers BERR160 and 35H00068-01M. If your original battery swells, won't hold a charge, or drops out suddenly, this is the direct swap.

• Iris, Iris 100, and S640 compatibility: All three models share the same battery bay dimensions, 3.7V nominal rail, and connector pinout — which is why a single cell covers the range. The BMS handshake protocol is identical across this family, so the phone's charge IC accepts the replacement without a firmware conflict.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the S640 platform. The BMS held the 4.2V charge ceiling correctly and the protection circuit tripped at the expected low-voltage cutoff without causing a hard fault loop.
• Fuel gauge recalibration on first use: On the first cycle after installation, run the phone down to auto-shutoff, then charge uninterrupted to 100% before use. This gives the fuel gauge IC one clean reference point against the new cell's discharge curve before the OS starts reading percentage from it.

Why the Iris reports wrong battery percentage after a cell swap

The HTC Iris uses a fuel gauge IC that builds its discharge model from accumulated charge and discharge data on the original cell. When you swap in a new cell, that learned curve no longer matches the new cell's actual voltage-to-capacity relationship. The IC keeps predicting from stale data, so the percentage you see on screen can be off by 10–20 points. One full discharge-to-shutoff followed by a complete uninterrupted charge resets the coulomb counter reference and brings the gauge back into accuracy.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity defect. Li-Polymer cells have a steep voltage drop in the final 20–25% of discharge, and if the phone's modem or screen pulls a high-current burst at that point, the cell voltage sags below the BMS cutoff threshold instantly. The phone shuts off even though the gauge still shows charge remaining. Let the phone complete two full discharge-charge cycles — the fuel gauge IC will map the new cell's cliff point and the OS will issue shutdown warnings before the cutoff is reached.