About this replacement
Wiko Robby — 3.7V Li-ion Replacement Battery (5212)
This is a 3.7V, 2000mAh Li-ion cell for the Wiko Robby smartphone. It replaces OEM part number 5212 and fits the Robby's battery bay directly. Capacity is rated at 7.4Wh, matching the original cell specification.
- Wiko Robby fit: The Robby uses a single-cell 3.7V Li-ion pack with a fixed connector and BMS handshake tied to that nominal voltage rail. Any cell outside that spec will be rejected at the charge IC level — this replacement stays within the required parameters.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Robby platform. The BMS accepted the cell without fault flags, and the charge IC held termination voltage at 4.2V as expected.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current charging runs against an uncalibrated reference.
Why the Robby reports wrong battery percentage after a cell swap
The Robby's fuel gauge IC builds its percentage model from the discharge curve of the previous cell. When a new cell goes in, that stored curve no longer matches actual cell behaviour. The IC may report 50% while the real state of charge is significantly lower or higher. One full discharge down to automatic shutoff, followed by an uninterrupted charge to 100%, forces the IC to write a new reference curve against the replacement cell.
Sudden shutdown at 20–30% on the replacement cell
This happens when the cell voltage drops below the modem's or display's minimum operating threshold under load, even though the fuel gauge still shows charge remaining. It is a voltage-cliff failure — the cell cannot sustain the voltage rail when the modem fires a transmission burst or the screen draws peak current. The fuel gauge IC has not yet mapped where this cliff sits on the new cell. Run one full calibration cycle first, then check whether shutdowns continue. If they do, verify resting cell voltage with a multimeter — it should read at or above 3.7V when the phone shows 30%.