UTEC V171 Replacement Battery 3.7V 1200mAh Li-ion

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

This is a 3.7V, 1200mAh Li-ion cell that replaces the original battery in the UTEC V171, V181, V201, and V566 mobile phones. The cell measures 53.00 × 33.90 × 5.70mm and matches the original form factor. If your phone is no longer holding charge or fails to power on, this cell replaces the degraded original.

• V171 / V181 / V201 / V566 compatibility: These four models share the same battery bay dimensions, 3.7V nominal voltage rail, and connector pinout — which is why a single cell covers the full group. The BMS communication protocol is identical across the series, so no handshake issues arise when swapping.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the V171 platform. The BMS accepted the new cell without triggering an overcurrent fault, and the protection circuit cut off correctly at the low-voltage threshold. Charge acceptance was normal from the first cycle.
• Fuel gauge recalibration on first use: After installing this cell, disable fast charging and run one complete discharge-to-charge cycle before resuming normal use. The fuel gauge IC on these phones calibrates its coulomb counter against the cell's actual discharge curve — skipping this step causes the OS to report inaccurate percentages for the first several cycles.

Sudden shutdown at 20–30% on the UTEC V171 after a cell swap

This happens because the fuel gauge IC still holds the discharge curve from the old, degraded cell. When the new cell's voltage drops under screen or modem load, the gauge reports a percentage that doesn't match what the cell can actually deliver at that load. The phone's protection logic sees the voltage cliff and shuts down before the display reads zero. One full discharge-charge cycle rewrites the gauge's reference curve and the shutdowns stop.

Phone warm near the battery compartment on first charge after replacement

A new cell typically has higher internal impedance than a broken-in one. The charge IC pushes current into that impedance, and the difference dissipates as heat — this is normal during the first one or two charge cycles. It should not feel hot, only warm. If the phone stays uncomfortably warm beyond the second full charge, check that the battery contacts are clean and seated flat, then measure charge voltage at the USB port — it should read between 4.9V and 5.1V under USB charging.