Kyocera Finecam S3 Replacement Battery BP-800S 3.7V 1000mAh

Kyocera Finecam S3 Series — 3.7V Li-ion Replacement Battery (BP-800S)

This is a 3.7V, 1000mAh Li-ion replacement cell for the Kyocera Finecam S3, Finecam S3L, and Finecam S5R digital cameras. It replaces OEM part numbers BP-800S, BP-900S, and BP-1000S. Voltage and physical footprint match the original — 68.20 × 24.85 × 6.50mm.

• Finecam S3, S3L, and S5R compatibility: These three bodies share the same battery bay dimensions, connector pinout, and BMS voltage thresholds. A single cell spec covers all three without modification.
• Bench tested on actual hardware: We cycled this cell through charge, rest, and discharge on compatible hardware. The BMS accepted the cell without error flags, and protection circuits triggered correctly at low-voltage cutoff.
• First-install charge cycle: Insert the battery and run a full charge inside the camera body or OEM charger before your first shoot. Some Kyocera BMS implementations need one full in-body charge cycle to calibrate the battery-remaining indicator accurately.

Flash recycling slowing down toward the end of a shoot

As a Li-ion cell approaches the lower end of its discharge curve, internal resistance rises and the current available for capacitor recharge drops. The Finecam's flash capacitor draws a sharp burst of current to recycle — that burst takes longer when the cell voltage sags below roughly 3.5V. The result is a noticeable pause between shots in flash mode, even though the battery indicator still shows charge remaining. If recycling lag appears early with a new cell, confirm the charger brought the pack to 4.2V before the shoot.

Battery percentage jumping or reading 100% then dropping suddenly

The Finecam maps remaining charge to a voltage-threshold table calibrated for the OEM cell's discharge curve. A replacement cell with a slightly different curve can cause the indicator to misread — showing full for longer, then stepping down sharply. This is a calibration issue in the camera's fuel gauge, not a fault in the cell itself. Running two or three full charge-to-cutoff cycles inside the camera body typically re-aligns the indicator to the new cell's actual discharge profile.