Nokia BL-4S 7610 Replacement Battery 3.7V 800mAh

Nokia 7610 / 7610 Supernova / 3600 Series — 3.7V Li-ion Replacement Battery (BL-4S)

This is a 3.7V, 800mAh Li-ion replacement for the Nokia BL-4S cell. It fits the Nokia 7610, 7610S, 7610 Supernova, 3600, and eight additional Nokia models sharing the same battery footprint. If your original BL-4S no longer holds a charge or the phone shuts down unexpectedly, this cell restores normal operation.

• 7610 / 7610S / Supernova / 3600 compatibility: These models share the same BL-4S form factor, connector pinout, and 3.7V charge cutoff. The battery slots in without modification and the charge IC on each device recognises the cell immediately.
• Bench tested on actual hardware: We cycled this cell on a Nokia 7610 and 3600 unit. The BMS accepted the charge handshake on first connection, held the 4.2V upper cutoff correctly, and the protection circuit triggered cleanly at the low-voltage threshold without latching.
• Fuel gauge recalibration on first install: After fitting this cell, run one complete discharge down to auto-shutoff, then charge uninterrupted to 100% before normal use. The Nokia fuel gauge IC calibrates its coulomb counter against the new cell's discharge curve during that first full cycle — skip it and the percentage readings will drift.

Why the Nokia 7610 reports wrong battery percentage after a cell swap

The 7610 uses a simple fuel gauge IC that tracks charge state against a stored discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The gauge reads voltage and maps it to an incorrect percentage. One full discharge-to-shutoff followed by an uninterrupted charge resets the reference and brings the displayed percentage back in line with actual capacity.

Sudden shutdown at 20–30% on the replacement BL-4S

This happens when the cell voltage drops below the load-sustain threshold before the displayed percentage reaches zero. Under combined screen and RF transmit load, the 7610 draws enough current to pull cell voltage below 3.4V while the gauge still shows charge remaining. The phone's power management circuit trips on undervoltage and shuts down instantly. If this occurs repeatedly, confirm the cell has completed at least one full calibration cycle — if shutdowns persist after that, check that the battery contacts on the phone are clean and making firm contact with the cell terminals.