BP-6M Nokia 3250 Replacement Battery 3.7V 1100mAh Li-ion

Nokia 3250 / 6280 / 9300i Series — 3.7V Li-ion Replacement Battery (BP-6M)

This is a 3.7V, 1100mAh Li-ion cell built to the BP-6M specification. It fits the Nokia 3250, 6280, 9300i, 3250 XpressMusic, and over ten additional Nokia handsets that share the same battery bay and connector. Drop it in when the original cell no longer holds charge through a normal day of calls and messaging.

• 3250, 6280, 9300i platform fit: These models share the BP-6M form factor — same 40.20 × 40.90 × 6.50mm footprint, same connector pin-out, and the same single-cell BMS handshake. A cell built to this spec seats and communicates correctly across all of them.
• Bench tested on actual hardware: We cycled this cell on a 3250 and a 6280. The BMS accepted the cell without error flags, charge termination triggered correctly at 4.2V, and the protection circuit tripped as expected at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first installation, run one full discharge down to automatic shutdown, then charge uninterrupted to 100% before using the phone heavily. The Nokia fuel gauge IC is calibrated to the old cell's discharge curve — one complete cycle resets the coulomb counter to the new cell's actual capacity.

Why the Nokia 3250 reports wrong battery percentage after a cell swap

Nokia's fuel gauge IC tracks capacity using a coulomb counter that was trained on the original cell's charge and discharge curve. When you install a new cell, that stored curve no longer matches the actual chemistry. The phone reads voltage against the old curve and reports a percentage that can be off by 15–25%. One full discharge-to-shutdown followed by a complete uninterrupted charge resets the counter and realigns the displayed percentage with true remaining capacity.

Sudden shutdown at 20–30% on the replacement cell

This happens when the fuel gauge IC still holds the degraded curve from the worn-out original cell. The phone thinks it has charge remaining, but the new cell's voltage profile at that state-of-charge drops below what the baseband processor needs under GSM transmission load. The BMS trips on undervoltage before the displayed percentage reaches zero. Force one complete discharge cycle — let the phone shut itself off naturally — then charge to 100% without interruption, and the cutoffs will align to the new cell's actual voltage curve.