Samsung AB653850CA SCH-i220 Replacement Battery 3.7V 1100mAh

Samsung SCH-i220 / SGH-T939 Series — 3.7V Li-ion Replacement Battery (AB653850CA)

This is a 3.7V, 1100mAh Li-ion battery for the Samsung SCH-i220 flip phone and compatible models including the SCH-I627 and SGH-T939. It replaces OEM part AB653850CA and its variants. Fit the battery when the original cell no longer holds charge through a normal day of calls and messaging.

• SCH-i220, SCH-I627, and SGH-T939 compatibility: These models share the same 3.7V cell format, connector pinout, and BMS communication protocol. One cell fits the full group — no firmware differences affect the handshake.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the SCH-i220 platform. The BMS accepted charge current correctly and terminated at the expected cutoff voltage without fault flags.
• Fuel gauge recalibration on first use: On first use after installation, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before enabling any fast-charge option. This gives the fuel gauge IC a clean reference curve against the new cell — skipping this step is the most common cause of erratic percentage readings on a fresh install.

Why the SCH-i220 reports wrong battery percentage after a cell swap

The fuel gauge IC stores a discharge curve calibrated to the original cell's internal resistance and capacity. A new cell has different characteristics, so the IC maps charge state against the wrong curve. The phone may show 40% remaining and then jump to 10% with no load change. One full discharge-charge cycle without interruption forces the IC to re-learn the curve against the replacement cell.

Sudden shutdown at 20–30% on the replacement cell

This happens when the phone places a brief high-current draw — an outgoing call connecting, backlight at full brightness, or radio searching for signal — and the cell voltage drops below the BMS cutoff threshold faster than the fuel gauge IC expects. The IC still reads 20–30% because it hasn't recalibrated, but the cell voltage has already hit the floor. Complete the recalibration cycle first. If shutdowns persist after calibration, confirm resting cell voltage reads above 3.6V with a multimeter before reinstalling.