Nokia BL-4C Replacement Battery 3.7V 750mAh Li-ion

Nokia 107 / 108 Series — 3.7V Li-ion Replacement Battery (BL-4C)

This is a 3.7V, 750mAh Li-ion replacement cell for the Nokia BL-4C battery slot. It fits the Nokia 107, 108, 1265, 1325, and over 34 additional Nokia models that share the same BL-4C footprint. If your phone is shutting down unexpectedly, failing to hold charge, or not powering on at all, this cell replaces the degraded original.

• BL-4C cross-model compatibility: All listed models share the BL-4C form factor — same 53 × 34 × 4.80mm dimensions, same 3.7V nominal voltage rail, and the same spring-contact connector. No adapter or modification required.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a BL-4C compatible handset. The BMS engaged charge cutoff correctly at 4.2V and the low-voltage protection tripped as expected. No thermal event or anomalous voltage drop was recorded.
• Fuel gauge recalibration on first use: After fitting this cell, run one complete discharge-to-charge cycle before relying on the battery percentage indicator. The Nokia 107's fuel gauge IC holds calibration data from the old cell — one full cycle rewrites it against the new cell's discharge curve.

Why the Nokia 107 reports wrong battery percentage after a cell swap

The Nokia 107 uses a simple coulomb-counting fuel gauge that builds its percentage model from repeated discharge cycles on the original cell. When you install a new cell, that learned curve is still in memory — it no longer matches the new cell's actual voltage-to-capacity relationship. The result is percentage readings that jump or stall, typically showing full charge for an extended period then dropping suddenly. One complete discharge-to-charge cycle forces the gauge to resample the new cell and correct its model.

Phone shuts off suddenly at 15–25% on the replacement cell

This happens when the fuel gauge reports remaining capacity but the cell voltage drops below the BMS cutoff threshold under load — typically during a call when the RF transmitter draws a brief current spike. The old fuel gauge curve predicts voltage incorrectly, so the phone has no warning before the BMS trips. It is not a faulty cell. Run one full discharge cycle until the phone auto-shuts off from low voltage, then charge to 100% without interruption. After that cycle, the gauge recalibrates and the sudden shutdowns stop.