HTC Desire 606w BO47100 Replacement Battery 3.8V 1800mAh

HTC Desire 606w / Desire 600 Series — 3.8V Li-ion Replacement Battery (BO47100)

This is a 3.8V, 1800mAh Li-ion replacement battery for the HTC Desire 606w, Desire 606t, Desire 600, and CP3 series smartphones. It replaces OEM part numbers BO47100, 35H00209-04M, and 35H00209-25M. Slot it in when the original cell no longer holds a usable charge through a normal day.

• Desire 600 series compatibility: The 606w, 606t, and Desire 600 share the same battery bay geometry, connector pinout, and BMS handshake protocol — one cell fits the entire line without modification.
• Bench tested on actual hardware: We cycled this cell on a Desire 606w and confirmed the BMS accepted charge handshake without fault codes, held voltage above 3.6V under sustained screen-on load, and reached full charge cutoff at 4.35V.
• First-cycle fuel gauge reset: After installation, run one full discharge down to automatic shutdown, then charge uninterrupted to 100% before using fast charging. This gives the fuel gauge IC a clean reference curve against the new cell — skip it and percentage readings will drift from the first hour.

Why the Desire 606w reports the wrong battery percentage after a cell swap

The Desire 606w uses a coulomb-counting fuel gauge IC that stores a learned discharge curve from the original cell. When you fit a new cell, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The gauge keeps reading against the old curve, so percentage display and the phone's low-battery threshold both drift. One complete discharge-charge cycle lets the IC recalibrate its reference points against the new cell's actual curve. After that cycle, percentage accuracy stabilises and low-battery shutdown triggers at the correct voltage.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage-cliff failure, not a capacity problem. Under high-current draw — active LTE modem, screen at full brightness, or GPS — the cell voltage sags sharply below the protection threshold before the displayed percentage catches up. The BMS cuts output to protect the cell, and the phone shuts off hard. It happens most on a new cell that hasn't completed a calibration cycle, because the fuel gauge overestimates remaining capacity. Run the first full discharge cycle, then check that the shutdown threshold in the phone's battery settings hasn't been raised by a previous app or power-saving profile — restore it to the default 3.4V cutoff.