Nokia BL-6C 2115i Replacement Battery 3.7V 1100mAh

Nokia 2115i Series — 3.7V Li-ion Replacement Battery (BL-6C)

This is a 3.7V, 1100mAh Li-ion cell built to the BL-6C specification. It fits the Nokia 2115i, 2116, 2116i, and 2125, along with 34 additional compatible models. If your original BL-6C has degraded or stopped holding a charge, this cell restores the phone to factory power levels.

• 2115i series compatibility: These Nokia models share the same BL-6C connector pinout, 3.7V nominal voltage rail, and physical footprint. The BMS handshake across the lineup is identical, so one cell covers the full compatibility list without modification.
• Bench tested on actual hardware: We ran the BL-6C cell through full charge and load cycles on a 2115i unit. The BMS accepted the new cell without a protection trip, and the charge IC stepped through its constant-current and constant-voltage phases cleanly at the rated 3.7V nominal.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to automatic shutoff before recharging. The Nokia 2115i's fuel gauge IC is calibrated against the old cell's discharge curve — skipping this step causes the phone to report inaccurate percentages from day one.

Why the Nokia 2115i reports wrong battery percentage after a cell swap

The 2115i uses a fuel gauge IC that tracks charge by mapping voltage against a stored discharge curve from the original cell. A new cell has a slightly different impedance profile, so the stored curve no longer matches real-world voltage readings. The gauge then reports percentages that are off — sometimes by 15–20%. One full discharge-to-shutoff followed by a full charge resets the coulomb counter reference points and brings the displayed percentage back in line with actual cell state.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under load — a voltage cliff — before the fuel gauge registers empty. On mid-2000s Nokia hardware, the processor and RF transmitter draw bursts of current that cause uncalibrated cells to sag below the BMS cutoff threshold around 3.2V. The phone shuts off even though the displayed percentage still shows charge remaining. The fix is the same calibration cycle: discharge fully to shutoff once, then charge uninterrupted to 100% to anchor the gauge to the new cell's actual 3.2V cutoff point.