BP-3L Nokia 303 Replacement Battery 3.7V 1300mAh Li-ion

Nokia 303 / Lumia 710 / Asha 303 — 3.7V Li-ion Replacement Battery (BP-3L)

This is a 3.7V, 1300mAh Li-ion replacement cell for the Nokia BP-3L battery slot. It fits the Nokia 303, 603, Lumia 710, Asha 303, and seven additional Nokia models that share the same BP-3L footprint. Dimensions are 66.00 × 43.90 × 4.60mm — the same physical envelope as the original.

• Multi-model Nokia platform fit: The 303, 603, Lumia 710, and Asha 303 share the BP-3L connector pinout and BMS handshake voltage thresholds. One cell covers the full range because Nokia standardised the charge IC communication across these models.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the Lumia 710 and Asha 303. The BMS accepted the charge handshake on the first cycle and held cutoff at 4.2V without thermal flags.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge to the auto-shutoff point before recharging. Nokia's fuel gauge IC calibrates its coulomb counter against the actual discharge curve — skipping this step causes the percentage display to read incorrectly for the first several cycles.

Why the Lumia 710 and Asha 303 report wrong battery percentage after a cell swap

Nokia's fuel gauge IC stores a discharge profile from the original cell. When a new cell goes in, the IC still references that old curve, so the percentage it displays drifts from actual state-of-charge. The fix is one full discharge-to-shutoff followed by an uninterrupted charge to 100%. After that single cycle, the coulomb counter resets its baseline to the new cell's actual capacity and the percentage readout stabilises.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem or screen draws a current spike and the cell voltage drops below the BMS protection threshold — even though the gauge still shows charge remaining. It is a voltage-under-load event, not a capacity problem. A new cell behaves this way before the fuel gauge IC has mapped its actual discharge curve. Complete the first full calibration cycle and the shutoff point will track correctly; the BMS cutoff sits at approximately 3.0V under load.