Want an A7 IV, FX3 or ZV-E1 to record or stream for hours? Stacking NP-FZ100 packs is the expensive way to do it. The stable answer is a dummy battery fed by an AC adapter or a large power bank. The dummy takes the place of the pack in the compartment and passes through continuous power, so runtime is set by the external source instead of the 2280mAh / roughly 16.4Wh inside one battery. If you only record a few minutes at a time, two spare packs in rotation will do. Past an hour of continuous recording, or for a full stream, go external.
Four options compared
| Option | Runtime | Upside | Watch out |
|---|---|---|---|
| Rotating NP-FZ100 packs | About 80–130 min of 4K each | No extra gear, full mobility | Swapping cuts the take; needs a person |
| Dummy battery + AC adapter | Unlimited where mains exist | Stable, cool, affordable | Tethered to an outlet; mind cable length |
| Dummy battery + power bank | Set by bank size, often 3–8 hours | Works outdoors, stays mobile | Confirm output voltage and wattage match |
| USB-C power to the body | Varies by body | One less accessory | Some bodies only charge, don’t run, while shooting |
External power solves the energy problem, not the heat problem. Recording can still stop on thermal protection or hit a file-size limit. Keep air moving around the body and stay out of direct sun for long 4K takes.
What a dummy battery is, and how to choose one
How it works
A dummy battery — also sold as a DC coupler — is a regulation module shaped like a pack. It slots into the compartment, meets the body’s contacts and stores nothing; it simply converts external power to the roughly 7.2V the camera wants. Three things decide whether a given unit is right:
- Voltage and polarity. It has to match the body’s spec. Reversed polarity can damage the camera, so confirm the model with the seller — A7 III, A7 IV, A7R V, A9 II, FX3 and so on.
- Current headroom. The adapter or bank should exceed the body’s peak draw; leaving 30% or more spare is the comfortable margin.
- Door and cable routing. Most units use a flat ribbon cable that exits through a notch in the battery door. Check your door has that notch and never pinch or fold the cable.
Matching the power source to the job
- Fixed streaming rig: mains adapter. Stable, and it frees up your power banks.
- Shooting on the move outdoors: a power bank with enough output, kept in open air and away from the body’s vents.
- Car or van: a 12V socket adapter or inverter. Stop-start systems cut power momentarily, so a supply with some buffering is worth having.
Wiring it up: checks first, power last
Power details differ by body. Video shooters can cross-check against battery setups for FX3 and FX30 creators, and A7S III owners against the A7S III video battery plan.
- Confirm body and battery type. The NP-FZ100 fits the A7 III / A7 IV / A7R series / A9 series / A1 / A6600 / A6700 / A7C II / FX3 / FX30 / ZV-E1 and others. The A6400, A6500, A7 II and A7R II use NP-FW50 and can’t take an FZ100 dummy. The Sony mirrorless battery cross-reference settles it.
- Check voltage before it goes in. Meter the output of the adapter or coupler and confirm it’s inside the body’s range. If it’s off, don’t install it.
- Install with the camera off. Push the dummy in the same way as a real pack until the latch seats, and run the ribbon out through the door notch.
- Power the supply, then the camera. Energizing the source first avoids a surge at switch-on.
- Confirm the body reads it. After power-up, check the charge display. “Cannot recognize this battery” means power down, refit and check for debris on the contacts.
- Test-record five minutes. Before going live, confirm the camera doesn’t shut down, overheat or reboot from unstable supply.
- Keep a fallback. For streaming, a real pack in the bag with a plan to switch over beats a stream that dies when the mains blips.
Safety notes
- Skip unlabeled modules. Anything without stated voltage, current and supported models may lack over-voltage and over-current protection. Buy from a listing that publishes the spec.
- Watch the heat. Both camera and power module warm up over long takes. Don’t stack a power bank on the body where the heat collects.
- Weather sealing is compromised. A cable out of the battery door breaks the original seal, so add cover in rain or snow.
- A dummy battery doesn’t charge. Don’t put it in a charger, and don’t try to charge the camera while it’s wired up.
- Your real packs still need care. If you run external power most of the time, the NP-FZ100 packs sit idle — top them up every three months and store them at 40–60%.
FAQ
Will a dummy battery hurt the camera over a full day?
Not by itself. The risk isn’t the power path, it’s a mismatch: wrong voltage, too little current or poor ventilation. Selection and airflow matter more than the decision to use one.
How big a power bank do I need?
Work from the body’s draw. As a rough guide for common 4K settings, an hour consumes roughly the energy of one to two NP-FZ100 packs — somewhere in the teens to twenties in watt-hours. Size the bank from that and leave headroom.
My body takes USB-C power. Do I still need a dummy?
Depends on the body. Some will charge while off or idle but behave differently while recording, and that has to be tested on your unit. For work that can’t drop, a dummy battery is the more predictable route.
How many real packs should I keep around?
Two minimum for mobile work, as backup and fallback. On mains at a fixed position, one or two covers the times you need to move the camera.
Spend on power for a fixed rig and on packs for a mobile one. Our NP-FZ100 compatible battery is rated at 2280mAh / 7.2V / roughly 16.4Wh, around $17.89 per pack, around $22.93 with one charger and around $36.74 for two batteries plus charger; the higher-capacity TNP-FZ100 (2400mAh) runs about $19.66 / $24.70 / $39.92. Streaming teams and production houses buying batteries or complete power kits in volume should go through wholesale inquiry — orders above 100 units are quoted by batch.