HTC Desire 825 Replacement Battery B2PUK100 3.85V 2600mAh

HTC Desire 825 — 3.85V Li-Polymer Replacement Battery (B2PUK100)

This is a 3.85V, 2600mAh (10.01Wh) Li-Polymer battery for the HTC Desire 825, Desire 825 TD-LTE, D825u, and Desire 825 Dual SIM. It replaces OEM part numbers B2PUK100, 35H00258-03M, and 35H00258-00M. Fit covers all regional variants of the Desire 825 lineup that share the same internal cell bay and connector.

• Desire 825 variant compatibility: The TD-LTE, Dual SIM, and D825u variants all use the same 3.85V cell bay, connector pinout, and BMS handshake as the base Desire 825. One cell format covers all of them — no adapter or modification required.
• Bench tested on actual hardware: We cycled this cell on a Desire 825 unit and confirmed the BMS accepted charge from both standard and fast-charge inputs. The protection circuit tripped correctly at low-voltage cutoff and reset cleanly on reconnection.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC build an accurate discharge curve against the new cell before high-current charging pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the Desire 825 after a cell swap

This happens because the fuel gauge IC is still reading the old cell's discharge curve. The new cell has a steeper voltage drop under modem and display load, so the phone hits the hardware cutoff before the reported percentage reaches zero. The phone shuts down not because the battery is faulty, but because the coulomb counter hasn't mapped the new cell yet. One full discharge-to-zero and uninterrupted charge cycle resolves it in most cases.

OS reporting incorrect battery percentage after replacement

The Desire 825 stores learned capacity data from the old cell in the fuel gauge IC. After swapping the cell, that stored data no longer matches the new cell's actual charge curve. The result is percentage readings that jump, stall, or read full when the cell is partially discharged. Drain the battery until the phone powers off, then charge uninterrupted to 100% — this forces the IC to recalibrate against the new cell's actual characteristics.