UTEC V171 Replacement Battery 3.7V 1000mAh Li-ion

UTEC V171 / V181 / V201 / V566 — 3.7V Li-ion Replacement Battery

This is a 3.7V 1000mAh Li-ion battery for the UTEC V171, V181, V201, and V566 smartphones. It fits the same cell bay across all four models and matches the original voltage rail and connector footprint. Capacity is 1000mAh (3.7Wh), identical to the factory specification.

• V171 / V181 / V201 / V566 platform fit: These four models share the same 3.7V single-cell architecture, connector pinout, and BMS handshake protocol — which is why one cell covers all of them. The charge IC on each device communicates with the same battery management registers.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a V171 unit. The BMS accepted the cell without rejection flags, and the charge IC completed a full constant-current/constant-voltage cycle without interruption.
• 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 map the new cell's discharge curve before applying high-current charging to an uncalibrated state-of-charge register.

Why the V171 reports wrong battery percentage after a cell swap

The fuel gauge IC on the V171 stores a learned discharge curve from the old cell in its coulomb counter registers. When a new cell goes in, those stored values no longer match the actual cell chemistry. The OS reads from the cached curve, not the real cell state, so percentages appear inflated or jump unpredictably. One full discharge-to-shutdown followed by an uninterrupted charge to 100% resets the calibration baseline.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display triggers a current spike and the cell voltage drops below the BMS cutoff threshold — even though the gauge still reads above 20%. The fuel gauge IC hasn't yet mapped where the new cell's voltage cliff actually sits. It cuts power to protect the cell before the display percentage catches up. Run two full discharge-charge cycles and the gauge IC will shift its low-voltage cutoff reference to match the new cell — shutdowns at 20–30% should stop after the second full cycle.