You’ve built a solid rig. Camera, monitor, wireless follow focus, transmitter, maybe a small on-camera light. Everything’s connected, everything’s on. Twenty minutes into the shoot, the battery dies.
It’s a scenario most working camera operators have experienced at least once. And almost every time, it’s avoidable — not by carrying more batteries, but by calculating how much power your rig actually draws before you arrive on set.
Understanding your rig’s power requirements is one of those professional fundamentals that separates well-prepared operators from operators who are constantly scrambling. Here’s how to do it properly.
The Key Unit: Watts
Everything in your rig consumes power measured in watts. Your battery stores energy measured in watt-hours (Wh). The relationship between the two tells you exactly how long your rig will run on a given battery.
The formula is straightforward:
Runtime (hours) = Battery capacity (Wh) ÷ Total rig draw (W)
A 98Wh battery powering a rig drawing 50W will run for just under two hours. The same battery powering a 90W rig runs for just over an hour. That difference determines whether you’re swapping batteries mid-interview or not.
Step One: Know Your Camera’s Draw
The camera itself is typically your largest single power consumer. Most professional cameras publish their power consumption in their specifications — look for a figure in watts or amps at 14.4V. As a general reference:
- Compact camcorders and mirrorless cameras: 10–25W
- Mid-size ENG shoulder cameras (Sony PXW, Panasonic AU series): 20–40W
- Larger broadcast shoulder cameras: 40–60W
- High-end cinema cameras (ARRI Alexa, RED): 50–90W, more with full accessories
Always verify with your specific camera’s documentation. Enabling certain features — high frame rates, in-camera recording to multiple codecs, active viewfinder heaters — increases draw.
Step Two: Add Your Accessories
This is where operators most commonly underestimate their power needs. Each D-Tap or regulated output powering an accessory adds to your total draw. Common accessories and approximate consumption:
- 5″ field monitor: 8–15W
- 7″ field monitor: 12–25W
- Wireless video transmitter: 5–18W depending on range and output
- Wireless follow focus receiver: 2–5W
- Wireless audio receiver: 1–3W
- On-camera LED light (small panel): 10–30W
- Wireless IFB/comms: 2–4W
Add these alongside your camera draw and you have your total rig consumption. A Sony PXW-FX9 at 30W, a 7″ monitor at 18W, a wireless transmitter at 12W, and a follow focus at 3W gives a combined draw of 63W. A 98Wh IDX V-Mount battery at that draw rate delivers just under 90 minutes of runtime — before accounting for battery inefficiency.
Step Three: Apply a Safety Margin
Published watt-hour ratings represent ideal conditions. In practice, battery capacity degrades over charge cycles, cold temperatures reduce output, and load variations mean your real-world runtime will be slightly less than the theoretical maximum.
A 15–20% safety margin is sensible for professional work. Using the example above, instead of planning for 90 minutes, plan for 70–75. If your shoot requires 90 minutes of uninterrupted runtime, you need either a higher-capacity battery or a swap plan.
IDX’s CinePower range is designed precisely for high-draw rigs and extended shooting windows where downtime for battery swaps isn’t acceptable.
Multiple Outputs From One Battery
Many professional V-Mount batteries provide multiple outputs simultaneously — typically a main 14.4V output for the camera, plus one or more D-Tap outputs for accessories. IDX’s V-Mount plates and accessories include distribution options for operators running multiple powered accessories from a single battery source.
Some operators prefer to power their camera from one battery and their accessories from a separate, smaller unit. This adds complexity to the rig but gives more granular control over runtime and reduces the risk of a single battery failure killing your entire setup.
On larger productions with multiple accessories, a proper power distribution box fed from a high-capacity V-Mount battery is often the cleanest solution — single battery, managed outputs, clear draw visibility.
Building a Power Inventory for Regular Jobs
If you work repeating formats — weekly sports fixtures, regular corporate shoots, a recurring documentary series — it’s worth building a power inventory for each setup. Document your standard rig, calculate the draw, note the battery capacity you use, and record actual runtime from experience.
Over time this becomes a reliable reference. You’ll know that your standard ENG setup runs for four hours on two 98Wh batteries. You’ll know that adding the wireless kit reduces that to three. You’ll know exactly what to pack for a six-hour shoot day.
That kind of preparation is what separates professional operators from operators who are constantly caught short. If you want to explore the full IDX range and find the right battery for your specific rig, browse the battery catalogue, or contact your nearest IDX dealer for advice.
