Panasonic Lumix S1 Replacement Battery DMW-BLJ31 7.4V 2200mAh

Panasonic Lumix S1 / S1R — 7.4V Li-ion Replacement Battery (DMW-BLJ31)

This is a 7.4V, 2200mAh Li-ion replacement for the DMW-BLJ31 battery. It fits the Panasonic Lumix S1 and S1R full-frame mirrorless cameras. Slot it in where the original sits — same dimensions at 72.56 × 41.60 × 21.26mm.

• Lumix S1 and S1R compatibility: Both cameras run the same 7.4V battery bay and share the DMW-BLJ31 connector pinout and BMS handshake protocol. One battery covers either body without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the S1 body. The BMS authenticated correctly, the battery-remaining indicator tracked accurately across discharge, and no false low-battery warnings triggered during sustained 4K recording.
• First-use charge cycle on S1 / S1R: Run one full charge cycle through the camera body or the OEM DMW-BTC13 charger before your first shoot. The S1 BMS maps its percentage display to the cell's discharge curve during that initial cycle — skipping it can cause erratic battery-level readings for the first few sessions.

Why the Lumix S1 drains this battery faster under continuous video than stills

The S1's full-frame sensor, Dual I.S. 2 stabilisation system, and heat management all draw from the same 7.4V rail simultaneously during video recording. Stills shooting is burst-and-idle — the processor and sensor cycle down between frames. Video keeps every subsystem active at once, so current draw is sustained rather than intermittent. At 4K 10-bit, the combined load pulls considerably more than the rated still-shot count suggests. If video is your primary use, budget for a second cell.

Battery percentage jumping erratically on the S1 display

This happens when the camera's BMS hasn't yet mapped the new cell's discharge curve. The S1 reads voltage thresholds and compares them against a stored profile — a new third-party cell discharges slightly differently than the OEM profile expects, causing the indicator to jump. The fix is straightforward: fully charge the battery via the camera body, discharge it completely through normal use, then recharge fully. After one complete cycle the indicator stabilises. If jumping persists beyond two cycles, check that the battery contacts on both cell and body are clean and making full contact.