About this replacement
Sony A7 Mark 3 / A7R Mark 3 / Alpha 1 — 7.5V Li-ion Replacement Battery (NP-FZ100)
This is a 7.5V, 2050mAh Li-ion cell built to the NP-FZ100 specification, fitting the Sony A7 Mark 3, A7R Mark 3, Alpha 1, Alpha 7C, and over 50 additional Alpha-series bodies. It slots into the same battery compartment as the OEM cell and communicates with the camera's battery management system over Sony's standard data line. Capacity is 15.38Wh — identical to the rated spec of the original.
- Alpha-series compatibility: Every listed body shares the same NP-FZ100 form factor, 7.5V nominal rail, and three-pin data interface. The BMS in each body reads cell voltage and temperature from the same contact points, so one replacement covers the full range without rewiring or adapters.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an A7 Mark 3 body, monitoring BMS handshake over the data pin. The cell was accepted on first install, reported accurate remaining charge after one full cycle, and held voltage within spec under continuous autofocus and EVF load.
- First-cycle conditioning on Alpha bodies: Sony Alpha bodies map the battery-remaining percentage to a learned discharge curve. Run the first full charge inside the camera body or OEM charger — not a third-party multi-charger — so the BMS can calibrate its fuel gauge against the actual cell from the start.
Why flash recycling slows before the battery indicator reaches zero
The A7 Mark 3 uses an internal capacitor to fire the flash, and that capacitor pulls a sharp recharge current spike between shots. As the cell approaches the lower end of its discharge curve — typically below 7.0V under load — it can no longer supply that spike fast enough to keep recycle time consistent. The camera body may still show one or two bars of charge because the BMS reads resting voltage, not load voltage. If flash recycling noticeably slows mid-shoot, the cell is near its actual cutoff even if the indicator disagrees. Swap the battery rather than waiting for the indicator to hit zero.
Battery percentage jumping erratically on the A7 Mark 3 display
Sony's fuel gauge maps percentage to a voltage-threshold table calibrated during BMS initialisation. A new replacement cell that hasn't completed one full charge-discharge cycle inside the camera body hasn't given the BMS enough data to anchor that table accurately. The result is percentage readings that jump — often dropping suddenly from 60% to 20%, or holding at a fixed number for long periods then falling sharply. One complete charge cycle from empty to full inside the camera body, not a third-party charger, resets the mapping. After that cycle, percentage readout on the A7 Mark 3 display will track the actual cell state correctly.