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

Avant S6 / S4 / S5 — 3.7V Li-ion Replacement Battery (NP-900)

This is a 3.7V, 600mAh lithium-ion cell that replaces the NP-900 battery in the Avant S6, S4, and S5 digital cameras. It shares the same footprint and connector as the original cell — 43.70 × 31.30 × 7.00mm. When the original cell no longer holds charge, this cell restores full camera operation.

• S6, S4, and S5 compatibility: All three models use the same NP-900 form factor, voltage rail, and connector pin-out. One cell works across the entire range without modification.
• Bench tested on actual hardware: We cycled this cell through the S6 body using the OEM charger. The BMS accepted the cell, reported charge state correctly, and held voltage above 3.5V through a standard discharge sequence.
• First-install charge cycle on the S6: Run the first full charge inside the camera body or OEM charger — not a generic USB adapter. Some camera BMS firmware needs one supervised charge cycle to map the new cell's discharge curve to the battery-remaining indicator accurately.

Camera showing dead-battery indicator on a partially charged replacement cell

The Avant S6 reads remaining capacity by mapping open-circuit voltage to a lookup table calibrated against the original cell's discharge curve. A new third-party cell may have a slightly different curve, so the camera sees a voltage point it maps to empty — even when the cell still has charge. One full charge-discharge cycle inside the camera body recalibrates the indicator. After that cycle, the percentage display should track the actual charge state within a few percent.

Battery percentage jumping erratically between shots

At 600mAh, the NP-900 cell has a small buffer. Each shot draws a burst of current for shutter actuation, image processing, and LCD refresh. If the indicator jumps — say, 80% to 50% — between shots, the BMS is seeing a momentary voltage sag and recalculating state-of-charge in real time. This usually settles after the first full charge cycle. If it persists past cycle two, check that terminal voltage at full charge reads 4.15–4.20V using a multimeter before re-inserting the cell.