Rollei Movieline SD50 Replacement Battery 3.7V 1100mAh

Rollei Movieline SD50 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 1100mAh Li-ion battery for the Rollei Movieline SD50 compact digital camcorder. It fits the SD card-based recording body directly and restores power to video capture and playback functions. Voltage and cell dimensions match the original: 38.25 × 38.15 × 9.50mm.

• Movieline SD50 fitment: The SD50 uses a compact single-cell 3.7V Li-ion pack with a specific footprint and tab connector orientation. This cell matches that footprint. No adapter or modification needed.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a calibrated rig, confirming the BMS responds correctly at both low-voltage cutoff and full-charge termination. Charge acceptance and cell balance behaved within spec across multiple cycles.
• First charge on the SD50: Run the first full charge cycle through the camcorder body itself, not a standalone charger. Some compact camcorder BMS implementations need one in-body charge cycle before the battery-remaining indicator tracks the new cell's discharge curve accurately.

Dead battery indicator showing on a partially charged replacement cell

The SD50 maps its battery-remaining display against a fixed voltage-threshold table calibrated to the original cell's discharge curve. A new third-party cell can sit at 3.6V — functionally charged — yet the camera reads it as flat because the resting voltage after shipping doesn't match the threshold the body expects at that point in the curve. One full in-body charge cycle resets that mapping. After that cycle, the indicator tracks normally.

Battery percentage jumping in large steps during recording

Compact camcorder bodies like the SD50 sample cell voltage at intervals rather than continuously. When a replacement cell has a slightly steeper discharge curve than the original, the body catches up in jumps — 80% to 55% with no warning, for example. This is a display calibration behaviour, not a cell fault. It typically smooths out after two or three full charge-discharge cycles as the BMS learns the new cell's curve. Run those cycles before a critical shoot.