Wiko Rainbow Jam 5222 Replacement Battery 3.7V 2000mAh

Wiko Rainbow Jam — 3.7V Li-ion Replacement Battery (5222)

This is a 3.7V Li-ion cell rated at 2000mAh (7.4Wh), built to the dimensions of the original Wiko 5222 battery at 70.00 × 60.00 × 4.40mm. It fits the Rainbow Jam, Freddy, Rainbow Lite 4G, and the 9669 handset. Swap it when the original cell no longer holds enough charge to get through a day of calls and messaging.

• Rainbow Jam and Freddy compatibility: These models share the same battery bay dimensions, connector pinout, and BMS handshake protocol, which is why a single cell covers the entire group. The voltage rail is identical across all listed models, so the fuel gauge IC reads the new cell without requiring a firmware patch.
• Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the Rainbow Jam. The BMS accepted the cell without triggering an overvoltage cutoff, and charge termination occurred correctly at 4.2V.
• Fuel gauge recalibration after swap: On the first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This allows the fuel gauge IC to map the new cell's discharge curve before high-current charging pushes into an uncalibrated coulomb counter.

Sudden shutdown at 20–30% on the Rainbow Jam after a cell swap

This happens because the fuel gauge IC is still using the discharge curve from the old, degraded cell. The new cell has a steeper voltage cliff at low charge, so the phone reads 25% right up until the cell voltage drops below what the modem and screen load demands — then it cuts out instantly. The fix is one full uncalibrated discharge cycle: let the phone run down until it shuts off on its own, then charge uninterrupted to 100%. After that cycle, the coulomb counter recalibrates and the percentage readings stabilise.

Phone warm near the battery slot during the first few charges

A fresh cell arrives with higher internal impedance than a broken-in one. The charge IC on the Rainbow Jam pushes current into that resistance, and some of it dissipates as heat. This is normal for the first two or three charge cycles and decreases as the cell's impedance settles. If the phone is still noticeably warm after five full cycles, check that the replacement cell is seated flat with no gap at the connector — a partially seated connector raises contact resistance and keeps the temperature elevated.