Vodafone 702NK Replacement Battery 3.7V 1000mAh

Vodafone 702NK / V804NK Series — 3.7V Li-ion Replacement Battery

This 3.7V, 1000mAh Li-ion cell replaces the original battery in the Vodafone 702NK, 702NKII, and V804NK smartphones. It fits the same battery bay and connector as the factory cell. Capacity is 1000mAh — identical to the original specification.

• 702NK, 702NKII, and V804NK platform fit: These three models share the same battery bay dimensions (53.00 × 33.90 × 5.70mm), voltage rail, and connector pinout. The cell slots into each device without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the bench. The BMS held voltage through the full discharge curve without triggering early cutoff, and charge acceptance was consistent across multiple cycles.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-charge cycle. This lets the fuel gauge IC map its calibration against the new cell's discharge curve before any high-current charging pushes current into an uncalibrated cell.

Why the 702NK reports wrong battery percentage after a cell swap

The fuel gauge IC in the 702NK stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual cell chemistry, so percentage readings drift — often reading 30–40% when the cell is nearly full. The fix is one full discharge down to automatic shutdown, then a full uninterrupted charge. After that single cycle, the fuel gauge IC resets its reference points against the new cell and percentage accuracy returns to normal.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or display draws a burst of current and the cell voltage drops below the BMS cutoff threshold — even though the gauge still shows charge remaining. It is a voltage cliff, not a capacity problem. The cell cannot sustain voltage under high instantaneous load at low state-of-charge. Run two full discharge-charge cycles to let the BMS and fuel gauge IC align on the actual low-voltage floor, typically around 3.0V under load.