I-Mobile 112 BL-75 Replacement Battery 3.7V 1200mAh

I-Mobile 112 / 213 Series — 3.7V Li-ion Replacement Battery (BL-75)

This is a 3.7V, 1200mAh Li-ion cell (4.44Wh) for the I-Mobile 112, 213, 225, and 1200 series smartphones. It replaces OEM part numbers BL-75 and BL-77. If your original battery swells, fails to hold a charge, or shuts down unexpectedly, this cell fits the same bay and connector.

• 112 / 213 / 225 / 1200 compatibility: These models share the same battery bay dimensions (53 × 34 × 5.70mm), voltage rail, and connector pinout — so a single cell covers the full group without adapter or modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on compatible hardware. The BMS accepted charge from USB without cutoff errors, and cell voltage held within spec under screen-on and call loads.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before high-current charging pushes current into an uncalibrated cell.

Why the I-Mobile 112 reports wrong battery percentage after a cell swap

The fuel gauge IC stores a learned discharge curve from the old cell. When a new cell goes in, that stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The phone reads voltage, maps it to the old curve, and reports an inaccurate percentage — often jumping or stalling at fixed values. One full discharge down to automatic shutdown, followed by an uninterrupted charge to 100%, forces the IC to rewrite its reference curve against the new cell.

Sudden shutdown at 20–30% on a freshly installed cell

This happens when the cell voltage drops sharply under modem or display load — a voltage cliff the OS percentage reading doesn't anticipate. The phone's low-battery threshold triggers a hard shutdown before the displayed percentage reaches zero. It is not a faulty cell. Run one full calibration cycle as described above, then confirm the shutdown no longer occurs below 3.6V under load. If it persists after two full cycles, check that the connector contacts are seated flush with no debris on the pins.