Lark Bjorn LARK SP-220 Replacement Battery 3.7V 750mAh Li-ion

Lark Bjorn SP-220 / SP-230 Dual SIM — 3.7V Li-ion Replacement Battery

This is a 3.7V Li-ion cell rated at 750mAh (2.78Wh), sized at 53.00 × 33.90 × 5.70mm. It fits the LARK SP-220, LARK SP-220 Dual, SP-230 Dual, and SP-230 Dual SIM smartphones. Capacity and voltage figures come from the product data, not estimated from third-party sources.

• SP-220 and SP-230 Dual SIM compatibility: Both the single-SIM SP-220 and the Dual SIM SP-230 variants share the same battery bay dimensions and 3.7V supply rail. The cell footprint — 53.00 × 33.90 × 5.70mm — seats correctly in both housings without modification to connectors or tabs.
• Bench tested on actual hardware: We ran charge and discharge cycles through the BMS on this cell format. The protection circuit triggered correctly at low-voltage cutoff, and charge acceptance was consistent across cycles with no anomalous heat at the connector tab.
• Fuel gauge recalibration on first use: After fitting this cell, disable fast charging for the first complete discharge-charge cycle. The fuel gauge IC on these Lark handsets calibrates its coulomb counter against the cell's discharge curve on that first full cycle — skipping this step leads to inaccurate percentage readings for weeks.

Sudden shutdown at 20–30% on the SP-220 after a cell swap

The SP-220's fuel gauge IC stores a discharge curve learned from the original cell. A new cell with a different internal impedance hits a voltage cliff the gauge doesn't expect — the phone reads 25% but the actual cell voltage under modem load drops below the shutdown threshold. This isn't a faulty replacement; it's a calibration mismatch. Run one full discharge to near-zero, then a full uninterrupted charge, and the gauge rewrites its reference curve. After that cycle, shutdowns at partial charge stop.

Phone shows wrong battery percentage for days after replacement

The coulomb counter in the SP-220's power management IC tracks charge in and out relative to a stored full-charge capacity figure tied to the old cell. Swapping the cell doesn't reset that figure automatically. The percentage display drifts — sometimes reading 100% after a short charge, or dropping 15 points suddenly under screen load. Force a full recalibration by draining the phone until it auto-shuts off, then charging to 100% without interruption. One complete cycle resets the stored capacity reference to match the new cell.