SVP C4D10T Nokia Tango Compatible Battery 3.7V 950mAh

SVP Tango / Deco Pro — 3.7V Li-ion Replacement Battery (C4D10T)

This SVP C4D10T is a 3.7V, 950mAh Li-ion cell that replaces the original battery in the Nokia Tango and Deco Pro smartphones. It slots in where the factory cell has degraded and can no longer hold a usable charge. Voltage and connector match the original, so no modification is needed.

• Tango and Deco Pro compatibility: Both handsets share the same battery bay dimensions, 3.7V nominal voltage rail, and contact layout — one cell fits both. The BMS on each device uses the same charge termination voltage, so the replacement cell charges correctly on either platform without a firmware change.
• Bench tested on actual hardware: We cycled this cell through full discharge and charge sequences on a Nokia Tango unit. The BMS accepted the replacement without triggering a protection cutoff, and the charge IC reached the correct 4.2V termination point on the first cycle.
• Fuel gauge recalibration on first use: On first installation, disable fast charging if the option is available and run one full discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the phone's fuel gauge IC one complete reference cycle against the new cell's discharge curve before it starts reporting accurate percentages.

Why the Tango reports wrong battery percentage after a cell swap

The Nokia Tango uses a fuel gauge IC that builds its charge estimates from a learned discharge curve stored during previous cycles with the old cell. When a new cell goes in, that stored curve no longer matches the new cell's actual voltage-to-capacity relationship. The IC reads a voltage that maps to the wrong percentage on the old curve, so the display shows figures that don't reflect real remaining charge. One full uninterrupted discharge-charge cycle resets the reference point and brings the reported percentage back into alignment with actual capacity.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display pulls a short burst of high current and the cell voltage drops sharply — past the BMS undervoltage threshold — even though the gauge still reads 20% or higher. It is a voltage cliff, not a capacity problem. A new cell that has not been calibrated yet can trigger this repeatedly in the first few cycles. After two or three full discharge-charge cycles, the fuel gauge IC recalibrates its curve and the shutdowns stop. If they continue past three cycles, check that the battery contacts are clean and making firm contact — a high-resistance connection amplifies the voltage drop under load.