Minox NP-900 Replacement Battery 3.7V 600mAh Li-ion

Minox DC 6311 / DC 4211 Series — 3.7V Li-ion Replacement Battery (NP-900)

This is a 3.7V, 600mAh Li-ion cell that replaces the NP-900 battery in Minox compact digital cameras. It fits the DC 6311, DC 4211, DC 5222, and DC 6011. Dimensions are 43.70 × 31.30 × 7.00mm — the same footprint as the original cell.

• DC 6311, DC 4211, DC 5222, DC 6011 compatibility: These four models share the same battery bay geometry, NP-900 connector pinout, and 3.7V voltage rail. One cell works across all four bodies without modification.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the DC 6311 body. The BMS accepted the cell on the first charge cycle and reported remaining capacity without fault flags.
• First-use charge cycle on DC series bodies: Insert the battery and charge it fully inside the camera body before shooting. Minox DC series firmware maps the battery-remaining indicator against a charge curve logged during the first in-body cycle — skipping this step causes the indicator to read erratically from the start.

Battery percentage jumping on the DC 6311 display after fitting a new cell

The DC 6311 maps its battery indicator against voltage thresholds calibrated to the original cell's discharge curve. A new replacement cell has a slightly different curve at mid-charge, which causes the indicator to skip readings or drop suddenly between shots. This is a display calibration issue, not a cell fault. Run one full in-body charge cycle from flat to full and the firmware re-maps to the new cell's curve.

Flash not recycling fully between shots near end of charge

The flash capacitor on the DC 6311 draws a sharp recharge current after each shot. When cell voltage drops below approximately 3.5V under load, that recharge current sags and the capacitor does not reach full charge before the next frame. The result is visibly dimmer flash output or a longer-than-normal ready light delay. If flash output drops noticeably, check cell voltage under load — at or below 3.4V the cell needs recharging.