Camera Rig Battery Runtime Calculator
Short answer
Runtime in hours equals watt-hours divided by total watts, then multiplied by about 0.85 for conversion losses and cell ageing. A 99 Wh battery running a 28 W rig gives roughly 3.5 hours in theory and about 3 hours in practice.
A rig that dies at 3pm is a rig that is not working, and the arithmetic to prevent it is two lines long. For most working builds the SmallRig VB99 Mini V-Mount, 99Wh at around $160 is the right battery, because 99 Wh sits just under the airline carry-on ceiling and still runs a full camera assembly for a substantial part of a day.
Calculator
Runs in your browser
Enter the draw of each device in watts, or use the typical figures already filled in, and choose your battery capacity.
Total load
0 W
at 14.4 V nominal
Runtime per battery
0 h
theoretical figure
Total on hand
0 h
The formula, and the honest correction to it
Runtime in hours equals watt-hours divided by watts. A 99 Wh cell powering a 28 W rig gives 3.5 hours. That is the number on the box, and it assumes a new battery at room temperature with no conversion losses.
In practice, multiply by about 0.85. The V-mount plate converts 14.4 V to whatever the camera wants and the conversion is not free. Cold weather reduces usable capacity meaningfully, and cells age. Planning on 0.85 means the day works out; planning on 1.00 means you find out at the worst moment.
Typical draw by device
| Device | Typical draw | Note |
|---|---|---|
| Mirrorless body, recording | 8 to 15 W | Higher with the screen bright and a fan running |
| Compact cinema camera | 18 to 30 W | Active cooling and SDI output both cost power |
| Full size cinema camera | 30 to 60 W | Before accessories |
| 5 inch monitor | 5 to 10 W | Brightness is the main variable |
| 7 inch high brightness monitor | 10 to 18 W | A 2000 nit panel is not cheap to run |
| Wireless video transmitter | 6 to 12 W | Receiver draws similar at the other end |
| Wireless follow focus motor | 3 to 8 W | Only while actually driving the lens |
| Field recorder | 3 to 8 W | Phantom power adds meaningfully per channel |
| 200 W LED at full output | 200 W plus | Empties a 99 Wh cell in under half an hour |
Battery capacity classes
The three capacities that matter
50 Wh for travel and light rigs, 99 Wh as the working standard, 212 Wh for studio and vehicle days where nothing has to fly.
SMALLRIG
SmallRig VB50 Mini V-Mount, 50Wh
50 Wh is under every common airline limit, which is the deciding factor for a rig that flies.
- Capacity
- 50 Wh
- USB-C
- PD 45 W
Two of these beat one big one for travel.
Check price
SMALLRIG
SmallRig VB99 Mini V-Mount, 99Wh
99 Wh sits right under the usual 100 Wh airline ceiling, and PD 100 W out means it charges a laptop between setups too.
- Capacity
- 99 Wh
- USB-C
- PD 100 W
The default V-mount for a documentary kit.
Check price
SMALLRIG
SmallRig VB212 V-Mount, 212Wh
212 Wh runs a camera, monitor and transmitter through a full day, at the cost of being unflyable in a carry-on.
- Capacity
- 212 Wh
Studio and vehicle work only.
Check priceThe 99 Wh figure is not a coincidence. The widely applied airline threshold for lithium batteries in carry-on baggage without special approval is 100 Wh, so manufacturers build right up to it. A SmallRig VB212 V-Mount, 212Wh is a better battery in every respect except that it cannot fly with you, which for most working shooters is disqualifying.
The Anton Bauer Titon Micro 90 V-Mount is the professional alternative at 98 Wh. You pay for build quality and for the fact that rental houses standardise on it, which matters when a battery spends years being dropped on concrete.
Wiring it up
Turning a battery into a rig power system
A plate to mount the cell and break out D-Tap and USB-C, a dummy battery cable to feed the camera, and a dual charger so a day never waits on one bay.
SMALLRIG
SmallRig Foldable V-Mount Battery Plate
The plate that puts a V-mount on a cage or a rod, with D-Tap and USB out so the monitor and transmitter stop needing their own cells.
- Outputs
- D-Tap, USB
This is what makes one battery power the rig.
Check price
SMALLRIG
SmallRig NP-FZ100 D-Tap Dummy Battery
The cable that turns a V-mount into camera power for Sony bodies, which is the whole reason to carry a V-mount at all.
- For
- Sony NP-FZ100 bodies
Match this to your camera's battery shape.
Check price
SMALLRIG
SmallRig Dual-Channel V-Mount Charger
Two bays, because one charger and three batteries means an overnight queue rather than a charged kit.
- Bays
- 2
Buy with your second battery.
Check priceThe SmallRig Foldable V-Mount Battery Plate is the piece people underestimate. Without it, a V-mount battery is a large object with no way to reach your camera. With it, one cell powers the body through a SmallRig NP-FZ100 D-Tap Dummy Battery dummy battery, the monitor over D-Tap and a transmitter over USB-C.
NP-F, and where it still makes sense
NP-F cells are around 47 Wh in the 970 size, which is roughly half a V-mount. They are cheap, light and almost every monitor and small light has a plate for them. The NEEWER NP-F970 Two-Battery Kit with Charger is the right first purchase for powering accessories on a starter rig.
What NP-F should not do is power a camera on a working rig, because that adds a second charging system and a second thing to monitor. The V-mount versus NP-F comparison works through the crossover point.
Worked example: a full documentary rig
A cinema body at 24 W, a bright seven inch monitor at 14 W, a transmitter at 10 W and a recorder at 5 W totals 53 W. A 99 Wh battery at the realistic 0.85 factor gives roughly 1.6 hours. That is a shock the first time you calculate it, and it is why professional documentary kits carry four batteries rather than two.
Drop the transmitter and the bright monitor for a five inch panel and the load falls to roughly 37 W, giving about 2.3 hours per cell. This is the actual reason experienced operators strip accessories they are not using: every watt is minutes off the day.
Charging plan
A single 99 Wh battery on a single-bay charger takes a couple of hours. Four batteries on one charger is an overnight queue that runs past your alarm. The SmallRig Dual-Channel V-Mount Charger with two bays is the minimum for a working kit, and the rule is to start charging the moment you get back rather than after you have offloaded the cards.
Next, from here
- Camera rig power guide
D-Tap, dummy batteries and wiring order.
- Best V-mount batteries
Capacities, plates and chargers.
- Runtime reference chart
Capacity against load in one table.
- V-mount versus NP-F
When the cheaper format is still right.
- Rig weight calculator
What that battery adds to what you carry.
- Run and gun working build
A rig built around one battery on purpose.
Common questions
- How do I work out battery runtime in hours?
- Divide watt-hours by total watts. A 99 Wh battery running a 25 W load lasts about four hours in theory. Then apply a real-world factor of about 0.85, because voltage conversion is not free, cells lose capacity in cold weather, and a battery that has been through many cycles no longer holds its rated figure.
- What does a camera rig actually draw?
- A mirrorless body draws roughly 8 to 15 W while recording, a cinema camera 20 to 35 W, a five inch monitor 5 to 10 W, a seven inch bright monitor 10 to 18 W, a wireless video transmitter 6 to 12 W, and a wireless focus motor 3 to 8 W in use. A fully loaded documentary rig commonly totals 40 to 60 W.
- Why is my battery not lasting as long as the maths says?
- Three usual reasons. Conversion losses in the plate and cables cost you something. Cold weather reduces usable capacity noticeably, sometimes by twenty percent or more near freezing. And cells age: a battery three years and several hundred cycles old may hold well under its rated watt-hours while still reporting full.
- What is the airline limit on camera batteries?
- The widely applied threshold is 100 Wh for carry-on without airline approval, which is why 99 Wh V-mount cells exist and why almost every travelling kit uses them. Batteries between 100 and 160 Wh usually require airline approval and a limit on quantity, and above 160 Wh they are generally not permitted. Always confirm with your carrier.
- Can one battery run my whole rig?
- That is exactly what a V-mount plate is for. A plate with D-Tap and USB-C outputs takes one battery and feeds the camera through a dummy battery cable, plus the monitor and a transmitter. It removes several charging systems and several failure points, and it is usually the single best upgrade on a working rig.
- Do lights change the calculation?
- Completely. A 200 W LED at full output empties a 99 Wh battery in under half an hour, and a 400 W class fixture does it in about fifteen minutes. Battery capable lighting is real but it is a short-run tool, so plan around output percentage, several large cells, or mains power where any exists.
Totalling your own rig weight against your gimbal payload? The Camera Rig Build Planner is the paid version of these pages: 8 printable worksheets you fill in with your own numbers, plus the full PDF, $29.