Wiko VOIX Replacement Battery 3.85V 3300mAh Li-Polymer

Wiko VOIX / U616AT — 3.85V Li-Polymer Replacement Battery (PT34H406082J)

This 3.85V, 3300mAh Li-Polymer cell replaces the original battery in the Wiko VOIX and U616AT smartphones. It matches the OEM footprint at 80.70 × 59.80 × 3.80mm, so it seats flush inside the chassis without any modification. Capacity figure is taken directly from product data — 12.71Wh.

• VOIX and U616AT compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell fits both without any wiring changes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS accepted the charge IC handshake correctly, held voltage under screen-on and modem load, and tripped protection at the expected cutoff without false positives.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging and run one full discharge down to automatic shutdown, then charge to 100% uninterrupted. This gives the coulomb counter a clean reference curve before high-current charging pushes current into an uncalibrated cell.

Sudden shutdown at 20–30% on a replacement cell

This is the most common complaint after a cell swap on the VOIX. The fuel gauge IC was calibrated against the old cell's discharge curve, so it reads voltage incorrectly near the bottom of the new cell's range. Under modem or display load, actual cell voltage drops faster than the gauge predicts, and the BMS trips protection before the OS gets a low-battery warning. One complete discharge-charge cycle resets the coulomb counter. After that cycle, the phone should shut down at or below 5% rather than cutting out at 20–30%.

Phone won't power on after the replacement cell sat in storage

Li-Polymer cells self-discharge during storage. If this cell dropped below roughly 2.5V per cell before installation, the BMS enters lockout mode and blocks all current flow to protect the cell from damage. Plugging straight into a fast charger won't break the lockout — the charge IC needs to see at least a trickle-charge pulse first. Connect to a slow 5V/1A USB charger and leave it for 20–30 minutes without pressing the power button. Once the cell recovers above 3.0V, the BMS releases and the phone will power on normally.