About this replacement
Wiko Sunny 2 Plus — 3.7V Li-ion Replacement Battery (S104-U59000-038)
This is a 3.7V 1800mAh Li-ion battery for the Wiko Sunny 2 Plus and V2600 smartphones. It replaces part numbers 2600 and S104-U59000-038. Install it when the original cell can no longer hold a charge or the phone shuts down unexpectedly before reaching 0%.
- Sunny 2 Plus and V2600 fit: Both the Sunny 2 Plus and V2600 share the same 3.7V battery bay, connector pinout, and BMS handshake protocol — one cell covers both. No adapter or wiring modification needed.
- Bench tested on actual hardware: We cycled this cell on the Sunny 2 Plus platform and confirmed the BMS accepted the charge handshake without fault codes. Voltage held steady across screen-on and modem-active loads.
- Fuel gauge recalibration on first use: After installation, disable fast charging and run one full discharge-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.
Sudden shutdown at 20–30% on the Sunny 2 Plus
This happens when the fuel gauge IC is still calibrated to the old, degraded cell's discharge curve. The new cell has a steeper voltage drop under combined modem and display load than the IC expects. When voltage sags below the cutoff threshold during a high-draw moment, the phone treats it as a dead cell and shuts down — even though charge remains. One full discharge-charge cycle at standard rate corrects the coulomb counter and stops the early cutoff.
Phone reports wrong battery percentage after cell swap
The Sunny 2 Plus stores the previous cell's capacity data in the fuel gauge IC. Swapping to a new 1800mAh cell does not automatically reset that data. The percentage shown on screen reflects the old curve until the IC recalibrates. Drain the phone to automatic shutdown, then charge uninterrupted to 100% — after that single cycle, the displayed percentage will track the new cell accurately.