Wiko Jerry 3702 Compatible Battery 3.7V 1600mAh

Wiko Jerry / Sunny 2 Plus / Sunny 3 — 3.7V Li-ion Replacement Battery (3702)

This is a 3.7V, 1600mAh Li-ion cell (5.92Wh) that replaces the original OEM part 3702 in the Wiko Jerry, Sunny 2 Plus, Sunny 3, and Lenny 1. It fits the same physical slot and connects to the same battery contacts without modification. Capacity figure comes from the product data, not a web estimate.

• Jerry, Sunny 2 Plus, Sunny 3, Lenny 1 platform fit: These Wiko budget-tier models share the same PCB layout, battery bay dimensions (78.42 × 50.00 × 4.25mm), and connector pinout. The BMS handshake and voltage rail are identical across the group, so one cell covers all listed variants.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Wiko Jerry unit. The BMS accepted the new cell without error flags on the first cycle. Charge termination triggered correctly at 4.2V and protection cutoff held at the expected low-voltage threshold.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging if your handset supports it and run one full discharge-charge cycle before normal use. The fuel gauge IC on these Wiko devices calibrates its coulomb counter against the actual discharge curve of the cell — skipping this step leaves the IC reading against the old cell's curve, which causes early percentage jumps.

Why the Wiko Jerry reports wrong battery percentage after a cell swap

The fuel gauge IC stores a learned discharge curve from the original cell. When you install a new cell, the IC still references that old curve to estimate state of charge. Until it recalibrates, the percentage readout can jump by 10–15 points mid-use or freeze near full for longer than expected. One complete discharge down to automatic shutdown, followed by a full charge to 100%, rewrites the coulomb counter baseline. After that single cycle, the percentage tracking stabilises against the new cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or screen pulls a current spike the cell cannot sustain at that state of charge — voltage drops below the BMS cutoff threshold before the percentage gauge has caught up. It is a voltage cliff, not a capacity fault. The fix is the same recalibration cycle: fully discharge the phone until it shuts itself off, then charge uninterrupted to 100%. If shutdowns persist past two full cycles, check that the battery contacts on the phone chassis are clean and making flat contact — a bent pin raises internal resistance and worsens the voltage sag under load.