About this replacement
Nokia 1220 / 1260 Series — 3.7V Li-ion Replacement Battery (BLC-2)
This is a 3.7V, 950mAh Li-ion replacement battery for Nokia 1220, 1221, 1260, 1261, and 32 additional compatible models. It uses OEM part numbers BLC-2, BLC-1, and BMC-3. The cell fits the standard battery bay on these Nokia handsets and connects via the original three-contact terminal strip.
- Nokia 1220/1260 platform compatibility: These models share the same 3.7V single-cell architecture, identical bay dimensions (53 × 39 × 7.50mm), and the same three-pin contact layout. One cell covers the full range without modification.
- Bench tested on actual hardware: We cycled this cell on a Nokia 1260 and monitored the BMS through charge cutoff and low-voltage protection. The BMS triggered correctly at both ends — no false cutoff, no thermal event during the CC/CV charge transition.
- Fuel gauge recalibration on first use: After fitting this cell, run one complete discharge-to-charge cycle before trusting the percentage readout. The phone's fuel gauge IC holds the old cell's discharge curve in memory. One full cycle overwrites it against the new cell's actual characteristics.
Why the Nokia 1220 reports wrong battery percentage after a cell swap
The fuel gauge IC on these Nokia handsets tracks charge state using a stored discharge curve from the previous cell. When a new cell goes in, the IC has no reference data for it. The percentage it displays is calculated against the old, degraded curve — so a full new cell might show 80% or lower. One complete discharge cycle from 100% down to the automatic cutoff point forces the IC to log the new cell's actual voltage behaviour and recalculate from there. After that first cycle, the readout stabilises.
Sudden shutdown at 20–30% on a replacement cell
This happens when the cell's internal resistance causes a voltage sag under the load of an active call or backlight burst. The phone's protection circuit reads the sag as a critically low voltage event and shuts down — even though the fuel gauge still shows charge remaining. It is not a faulty cell; it is an uncalibrated fuel gauge pairing a voltage cliff with a percentage that does not yet reflect the new cell's curve. Run the phone down to automatic shutoff once, charge it uninterrupted to full, and check the shutoff voltage resets above 3.4V on the next cycle.