Rollei NP-900 Prego DP5200 Replacement Battery 3.7V 600mAh

Rollei Prego DP5200 Series — 3.7V Li-ion Replacement Battery (NP-900)

This is a 3.7V 600mAh Li-ion cell built to the NP-900 form factor. It fits the Rollei Prego DP5200, DP4200, DP5700, and DP6200 compact digital cameras, along with several other Prego-series bodies sharing the same battery bay. Dimensions are 43.70 × 31.30 × 7.00mm — same footprint as the original cell.

• Prego DP-series compatibility: These Rollei Prego models share the same battery bay geometry, contact layout, and 3.7V supply rail. The BMS handshake requirement is consistent across the DP4200, DP5200, DP5700, and DP6200, so one cell covers all four bodies without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on a Prego-series body. The BMS accepted the cell, reported charge state correctly after one full charge cycle, and held voltage within the expected discharge curve under both still capture and playback draw.
• First-use charge cycle on the Prego body: Run the first full charge from within the camera body or the OEM charger before any shooting. Some Prego BMS firmware maps battery-remaining display against a charge curve it only calibrates during the first in-body cycle — skipping this step causes the indicator to read inaccurately from the start.

Dead battery indicator on a partially charged NP-900 replacement

The Prego body reads battery state by comparing measured cell voltage against a stored discharge curve. A new third-party cell can have a slightly different resting voltage profile than the original Rollei cell, which causes the camera to interpret a partially charged state as empty. This is a calibration issue, not a faulty cell. Run one complete charge cycle from flat to full inside the camera body — the BMS resets its reference point against the actual cell voltage and the indicator stabilises from that point forward.

Battery percentage jumping erratically during a shoot

Erratic percentage jumps happen when the camera's voltage-threshold map doesn't align with the new cell's discharge curve. The Prego firmware was calibrated against the original NP-900's specific voltage steps — a replacement cell discharging along a slightly different curve triggers multiple threshold crossings in quick succession. The display jumps because the BMS is re-evaluating state at each threshold crossing rather than interpolating smoothly. Charge the cell fully in-camera once, then discharge it fully through normal shooting to let the BMS remap its thresholds against the actual cell.