HTC 7 Pro 35H00123-29M Replacement Battery 3.7V 1600mAh

HTC 7 Pro / T7576 — 3.7V Li-ion Replacement Battery (35H00123-29M)

This is a 3.7V 1600mAh Li-ion replacement battery for the HTC 7 Pro and T7576 smartphones. It replaces OEM part numbers 35H00123-29M and BA S550 when the original cell has degraded past usable capacity. Voltage and capacity match the original specification exactly.

• 7 Pro and T7576 compatibility: Both the 7 Pro and T7576 share the same battery bay geometry, connector pinout, and 3.7V nominal voltage rail. The same cell fits both devices without modification — the BMS handshake protocol is identical across this model pair.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the 7 Pro platform. The BMS accepted the charge profile correctly, protection circuits tripped at expected low-voltage thresholds, and the charge IC communicated without fault codes.
• Fuel gauge recalibration on first cycle: After installation, disable any fast-charge accessory and run one complete discharge-to-charge cycle at standard current. This allows the fuel gauge IC to map the new cell's discharge curve before the OS starts reporting percentage — skipping this step causes erratic percentage readings in the first few days.

Sudden shutdown at 20–30% on the HTC 7 Pro after a cell swap

This happens because the fuel gauge IC is still referencing the old cell's discharge curve. When the new cell hits a voltage point that the old curve maps to 20–30%, the actual cell voltage may already be dropping below what the modem and display need to sustain load. The phone shuts down to protect the hardware, not because the new cell is faulty. Run two full discharge-charge cycles without interruption and the fuel gauge IC will update its curve to match the new cell — shutdowns at false percentages stop after calibration settles.

Phone warm near the battery bay during the first charge

A new cell typically has higher internal impedance than a fully conditioned one. During the first few charge cycles, the charge IC pushes current into that higher-impedance cell, and the extra resistive loss shows up as heat near the battery bay. This is expected behaviour and reduces as the cell cycles. If warmth persists beyond the third full charge cycle, check that the charge current setting in your charger does not exceed 1C for a 1600mAh cell — that means no more than 1600mA input current.