Every prep raises this question, and for ten years the answer changed every eighteen months. Two recent releases put it back on the table: the Astera QuikBeam, a small 20 W Fresnel with a swappable battery, and the Nanlux Evoke 5C, a 6 W pocket source rated for immersion.
I have had neither on a set. What follows reasons from the published figures, sourced at the bottom, and from arithmetic anyone can redo. That is the useful part: on this subject, everything that matters can be checked with one division.
Two new fixtures, and what they say about the market
The Astera QuikBeam is a small Fresnel with a continuous 13 to 60° zoom, quoted at 20 W of draw for a stated 200 W tungsten equivalent. It weighs 1617 g, it is rated IP65, it carries CRMX on board, and its QuikBrick battery swaps by hand.
The Nanlux Evoke 5C fits in a pocket: 160 g, 6 W, IP67 to one metre for thirty minutes, an internal 3.7 V 1300 mAh cell, an eight emitter engine, a stated 1,000 to 20,000 K range, CRI and TLCI both quoted at 98. List price 219 dollars.
On the tungsten equivalence, the usual caution applies: a manufacturer quoting a 200 W equivalent is talking about illuminance at a point, not output. The QuikBeam concentrates 20 W into an adjustable cone and produces a good centre reading. Put diffusion in front of it and the equivalence evaporates, because a frame integrates everything that hits it instead of measuring one point.
The Evoke 5C photometry, by contrast, checks out in a single line. Nanlux publishes 2,026 lux at 0.5 m and 496 lux at 1 m. Inverse square gives 2,026 divided by four, or 507. Two per cent apart: the source behaves as a point, and you can extrapolate with confidence, roughly 124 lux at 2 m.
What these two releases say about the market is more telling than their spec sheets. Nobody has announced a 1,200 W head with a battery inside. Battery power advances where it fits, which is at the bottom of the range.
Ninety minutes, whatever the size of the head
Take four fixtures from very different classes and look at their runtime at full output. The Evoke 5C holds 50 minutes. The QuikBeam holds 1 h 20 on one QuikBrick. Astera's Titan Tube, 48 W of LED draw, holds 1 h 45. An Aputure LS 600c Pro at 720 W, fed by two 290 Wh V-mount blocks, will hold 48 minutes.
None of them does a day. None of them does half a day. And the order of magnitude does not follow the size of the head, because the battery is sized to the fixture: the more it draws, the bigger the block, and the ratio stays put.
So the long runtimes printed on spec sheets have to be read backwards. Astera quotes up to 20 hours on the Titan Tube. Its battery is around 84 Wh, so those 20 hours correspond to 4.2 W, less than a tenth of its full draw. The number is accurate and it describes no working setup.
Runtime is one division
Hours of runtime equals watt-hours on board divided by watts drawn. Everything else is margin.
On the Evoke 5C the arithmetic lands exactly. Its cell is quoted at 3.7 V and 1300 mAh, so 4.81 Wh. Divided by 6 W that gives 0.80 hours, or 48 minutes. The manufacturer states 50 minutes. In other words the published figure spends the entire capacity, with nothing held back for cold, cell ageing or converter losses.
Hence the rule I use in prep: divide, then take off a fifth. A 98 Wh V-mount on a 100 W fixture gives an hour on paper and three quarters of an hour on set. At five degrees on a night exterior, expect less again, and carry the margin in blocks rather than in optimism.
On a power station the division is the same but the loss is doubled. A 1,024 Wh EcoFlow Delta 2 feeding a 300 W COB gives 3 h 25 in theory, call it 2 h 45 in practice. The station puts out 230 V through an inverter, and the fixture's own supply rectifies it straight back to DC. You pay for the conversion twice.
No cable: what that actually changes on a location
The gain does not show up on a spec sheet. A fixture with no cable is a run you do not pull, a walkway you do not tape and flag, a location you do not drill and will hand back as you found it.
Above all it is a fixture you reposition in ten seconds. On a relight, that is where the day is won: the tube you set down somewhere else without wondering where it is fed from, the head you hand to someone for a backlight on the fly, the small fixture you wedge into a car. The Evoke 5C's IP67 rating adds rain and water to the list of places you can put it.
There is a third route everyone forgets: PoE. The QuikBeam runs off a network cable, up to 100 m from its injector. One thin cable carrying signal and power in the same jacket, and no power run to the position at all. It only works at this scale of draw. At this scale, it solves the problem better than a battery does.
The battery stock becomes a department of its own
The criterion that decides is not runtime, it is whether the battery swaps. The QuikBrick comes out by hand and returns to 80 % in 40 minutes. The Evoke 5C's cell is internal, so is the Titan Tube's: those fixtures do not get relieved, they get plugged back in.
The difference is brutal in practice. With two QuikBricks per head you run indefinitely: 1 h 20 of runtime against 40 minutes of charge, the maths works. With an internal cell, the fixture goes back on a power strip between setups. The power has not gone away, it has moved to the charging table, and the charging table is on mains.
Then there is travel. The IATA rules leave no room for interpretation: up to 100 Wh, a battery flies in the cabin with no paperwork; between 100 and 160 Wh you need the airline's written approval, a maximum of two spares, and cabin only; above 160 Wh it is forbidden in passenger baggage. A QuikBrick at roughly 27 Wh travels. A 290 Wh block goes as freight, or gets rented at destination.
On a small crew, somebody ends up spending an hour a day on chargers. It appears on no quote and it shows every day.
Where I put mains back
My threshold, and I stand behind it: below 50 W per fixture and for less than two hours of burn, battery wins outright. Accent lights, practicals, tubes in frame, anything you move constantly, none of it has any reason to be cabled any more.
Above 200 W per fixture, or as soon as you are running all day at full output, or beyond four or five heads, mains takes the advantage back. The argument is not a technical one. It is about cost, and about who does the work. The stock of blocks and the rotation time cost more than the run you would have pulled that morning.
In between, the location decides. Distance to the supply, whether you can tape and flag a walkway, and above all how often you move, which counts for more than the other two. A location where you shift every twenty minutes leans towards battery even at 150 W.
And there is a middle answer that is often the right one: the power station. Silent, no exhaust, feeding a normal distro. The catalogue lists several, from the 1,024 Wh EcoFlow Delta 2 to the 2.1 kWh Instagrid ONE and the 10 kWh Wattman. A station is not a battery fixture. It is a quiet substitute for mains, and on a night interior it settles more problems than either of the other two options.
So, caught up? At the bottom of the range, yes, and for a while now. Above 200 W, the answer is the one from five years ago: pull a run, or bring a genny.
Sources
- Astera, QuikBeam
- Astera, QuikBrick
- Astera, Titan Tube datasheet (PDF)
- Nanlux, Evoke 5C
- Aputure, LS 600 Pro power options
- IATA, travelling with lithium batteries
Frequently asked questions
Will a battery fixture last a shooting day?
No, and no class of fixture is an exception. At full output, runtimes go from around 50 minutes for a 6 W pocket source to 1 h 45 for a 48 W tube, and a 720 W head fed by two 290 Wh V-mount blocks will hold about 48 minutes. Since the battery is sized to the fixture, the ratio stays the same whatever the size. A day on battery means block swaps or recharges, and someone to handle them.
How do you work out the runtime of a battery fixture?
Divide the watt-hours on board by the watts drawn, then take off a fifth. A 98 Wh V-mount on a 100 W fixture gives an hour on paper and three quarters of an hour in real conditions. Manufacturer figures are generally worked out on total capacity: the Evoke 5C's 4.81 Wh cell divided by its 6 W draw gives 48 minutes, and the manufacturer quotes 50. Cold, cell age and conversion losses come out of your margin, not theirs.
Can you fly with set batteries?
Up to 100 Wh a battery travels in the cabin with no paperwork. Between 100 and 160 Wh you need the airline's written approval before boarding, a maximum of two spares, and cabin only. Above 160 Wh it is forbidden in passenger baggage and the block goes as freight. A QuikBrick at roughly 27 Wh gets through without trouble, a 290 Wh V-mount does not. Spare batteries never go in the hold, and their terminals get protected.
Above what wattage does mains become simpler again?
Below 50 W per fixture and for less than two hours of continuous use, battery wins. Above 200 W per fixture, or as soon as you run all day at full output, or beyond four or five heads, a mains run or a genny becomes cheaper and lighter to organise. In between, it comes down to how often you move and how far you are from the supply.
Can a power station replace a generator?
On low draws and short durations, yes, and it wins on noise every time. A station delivers a stock of energy, not unlimited power: 10 kWh on a 3 kW load is 3 h 20, whereas a genny runs as long as there is fuel. For a night interior with a few LED heads, the station is often the better answer. For an exterior with big units, the genny remains the only choice.