Verizon XV6600 Replacement Battery 3.7V 4200mAh PH26B

Verizon XV6600 — 3.7V Li-ion Replacement Battery (PH26B)

This 3.7V Li-ion cell replaces the original PH26B battery in the Verizon XV6600 Windows Mobile smartphone. Capacity is 4200mAh (15.54Wh). It fits the XV6600 directly using the original battery compartment and connector.

• XV6600 fit specifics: The XV6600 uses a single-cell Li-ion pack with a proprietary connector keyed to the AHTXDSSN form factor. The BMS handshake is straightforward — no encrypted authentication chip — so the replacement cell communicates with the fuel gauge IC without additional pairing steps.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the XV6600 platform. The BMS held charge cutoff at 4.2V and low-voltage protection tripped correctly before cell damage could occur.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to auto-shutdown, then charge uninterrupted to 100%. The XV6600's fuel gauge IC was calibrated against the original cell's discharge curve — one full cycle resets that reference against the new cell so percentage readings stay accurate.

Why the XV6600 reports wrong battery percentage after a cell swap

The XV6600 uses a coulomb-counting fuel gauge IC that tracks charge in and out relative to a stored discharge curve. When you swap cells, the IC still references the old cell's profile — so a 4200mAh cell gets measured against a worn, lower-capacity baseline. This causes the percentage display to jump, stall, or read 100% well before the cell is actually full. One full discharge-to-shutdown followed by an uninterrupted charge resets the coulomb counter and aligns it to the new cell's actual capacity.

Sudden shutdown at 20–30% on the XV6600 after replacement

This happens when the fuel gauge IC hasn't completed its first full recalibration cycle and the voltage estimate is running ahead of actual cell voltage. Under screen-on or radio load, the cell voltage dips sharply near the lower end of its curve — faster than the uncalibrated IC predicts — and the BMS trips the low-voltage cutoff. The phone shuts down even though the display still shows 20–30%. Complete one full discharge-to-shutdown cycle, then charge to 100% without interruption. After that cycle, the IC recalculates the voltage cliff point and shutdown behaviour normalises.