About this replacement
Fujifilm GFX 50S / Medium Format GFX — 10.8V Li-ion Replacement Battery (NP-T125)
This is a 10.8V, 1000mAh Li-ion replacement for the Fujifilm NP-T125 battery. It fits the GFX 50S and the broader Medium Format GFX camera system. Voltage and cell chemistry match the OEM specification exactly.
- GFX system compatibility: The GFX 50S and GFX system share the NP-T125 form factor, connector pinout, and 10.8V rail. The BMS in each body communicates over the same data lines, so one cell works across both platforms without modification.
- Bench tested on actual hardware: We cycled this cell through the GFX 50S body and an OEM Fujifilm BC-T125 charger. The BMS accepted the cell, voltage hold was consistent across discharge, and the protection circuit triggered correctly at low-cell cutoff.
- First charge protocol for GFX bodies: Run the first full charge inside the camera body or OEM charger before shooting — not a third-party universal charger. The GFX BMS maps battery-remaining percentages against a charge curve it builds on first contact. Skipping this step causes the indicator to read inaccurately from the first frame.
Why the GFX 50S battery percentage jumps erratically with a new cell
The GFX body tracks remaining charge by mapping voltage against a stored discharge curve. A new third-party cell has a slightly different discharge curve than the OEM cell the body originally calibrated to. Until the body logs a full charge-to-depletion cycle on the new cell, the percentage display interpolates against the wrong reference points. Run one full cycle — charge to 100%, shoot until the body shuts down from low battery — and the indicator stabilises. After that cycle, percentage readings align correctly with actual remaining capacity.
GFX body shows "no battery" or "incompatible battery" on a valid replacement cell
The GFX BMS performs an authentication handshake on insertion. If the cell has been stored below roughly 3.0V per cell from extended shelf time, the battery voltage is too low for the handshake to complete and the body rejects it. Place the cell in the BC-T125 OEM charger first — not the camera body — and let it charge from flat. The charger bypasses the body's authentication gate and can recover a deeply discharged cell. Once the charger brings it to full charge, reinsert into the body and the handshake completes at 10.8V nominal.