Samsung SCH-I515 Galaxy S II Replacement Battery 3.7V 3300mAh

Samsung SCH-I515 — 3.7V Li-ion 3300mAh Replacement Battery

This is a 3.7V, 3300mAh Li-ion replacement battery for the Samsung SCH-I515 Galaxy S II 4G LTE smartphone. It fits the removable battery bay directly and restores power to the device when the original cell has degraded beyond useful capacity. Capacity is rated at 12.21Wh.

• SCH-I515 fitment: The SCH-I515 uses a specific bay depth and connector orientation shared with the Verizon variant of the Galaxy S II LTE line. This cell matches those physical dimensions — 56.00 x 51.00 x 11.00mm — and the contact polarity required by the device's charge IC.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the SCH-I515 platform and confirmed the BMS handshake completes correctly. The protection circuit engages at the expected low-voltage cutoff, and the charge IC accepted a full charge cycle without error flags.
• Fuel gauge recalibration on first use: Disable fast charging for the first complete discharge-charge cycle after installing this cell. The SCH-I515's fuel gauge IC is still calibrated to the old cell's discharge curve. Running one full cycle at standard charge current lets the coulomb counter recalibrate before high-current charging is applied to an uncalibrated cell.

Why the SCH-I515 shuts down suddenly at 20–30% after a cell swap

The SCH-I515's fuel gauge IC maps percentage to voltage based on the discharge curve of the original cell. A new cell with a slightly different curve will reach its actual voltage floor before the gauge expects it. Under LTE modem load or screen-on draw, the cell voltage drops sharply past the BMS cutoff threshold — and the phone shuts off even though the display shows charge remaining. One full discharge-charge cycle resets the coulomb counter against the new cell's actual curve and eliminates the premature cutoff.

Phone showing erratic percentage jumps after battery replacement

Erratic percentage readings — jumping from 45% to 60% or dropping 15% in seconds — happen because the fuel gauge IC is still using the old cell's internal resistance model. The coulomb counter accumulates error rapidly when the reference data doesn't match the new cell's impedance. Drain the battery until the phone powers off, then charge uninterrupted to 100% without removing the cable early. After one complete cycle, the gauge recalibrates and percentage reporting stabilises.