BOPKX100 HTC Desire 626 Replacement Battery 3.8V 1900mAh

HTC Desire 626 Series — 3.8V Li-Polymer Replacement Battery (BOPKX100)

This is a 3.8V, 1900mAh Li-Polymer battery for the HTC Desire 626, Desire 626s, Desire 626d, and A32. It replaces OEM part numbers BOPKX100, 35H00237-00M, 35H00237-01M, 35H00237-04M, and 35H00237-05M. Physical dimensions are 66.84 × 57.02 × 3.42 mm — verify your original cell matches before installation.

• Desire 626 variant compatibility: The 626, 626s, and 626d all run the same 3.8V battery rail with the same connector pinout and BMS handshake protocol. The cell form factor and protection circuit are shared across these variants, so one cell covers the full range without modification.
• Bench tested on actual hardware: We ran this cell in a Desire 626 unit and confirmed the BMS accepted the new cell without error flags. The charge IC completed a full CC-CV cycle, and the protection circuit triggered correctly at the high-voltage cutoff.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging for one complete discharge-charge cycle. The fuel gauge IC uses a coulomb counter calibrated to the old cell's discharge curve — running one unconstrained cycle first lets it reset that baseline before high-current charging begins.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC still holds the discharge curve from the degraded original cell. The new cell has a steeper voltage cliff near depletion — the phone's SOC estimate drifts, and the hardware undervoltage cutoff fires before the OS percentage reaches zero. The fix is a full calibration cycle: drain the phone until it powers off on its own, then charge uninterrupted to 100% with the screen off. After one complete cycle, the coulomb counter resets to the new cell's actual curve.

Phone warm near the battery compartment during the first charge

A new Li-Polymer cell has higher internal impedance than a broken-in cell. During the first charge cycle, the charge IC pushes current into that higher-impedance cell, which dissipates more energy as heat than you'd see after a few cycles. This is normal and temporary — internal impedance drops after two to three full cycles. If the compartment stays hot beyond the first two charges, check that the charge IC has not defaulted to an unthrottled current setting from a corrupted power profile.