In Part One we looked at how to read camera battery specifications, how to calculate battery life and what the ideal size of a battery should be. In this part we’ll look at:
- What constitutes a battery ‘system’ and why we need one,
- How to find the right camera battery system for your gear, and
- A detailed example of calculating which and how many camera batteries one needs for a Canon C300 system.
IMPORTANT! Tinkering with electricity is dangerous, and can be fatal to you or your gear if you don’t know what you’re doing. Instructions presented here are just broad suggestions and are not to be copied. Please consult a certified electrician or engineer for practical use. I’m not responsible if you follow my suggestions and something bad happens.
The battery system
A ‘system’ by definition means a collection of parts. There’s the battery, and then there are other things. All said and done, the primary purpose of any battery system is to provide power to a camera rig. In addition, the system has to:
- Connect physically to the camera or rig in an ergonomic fashion,
- Allow for adapters and cable management,
- Provide charging, testing and display features,
- Provide voltage and power management features.
Let’s see why all these things are important.
Core parts of any battery system
Here are the basic building blocks of a battery system. First, the battery:
As we saw in Part One, this is a Li-ion battery and probably has four 3.6V cells, which is why it’s huge. It is designed to do three ‘more’ things than a regular battery:
- Provide more power per ‘battery block’ (some also call it a ‘brick’) because more than one device needs to be powered,
- Protect the battery from the weather, bumps and daily professional use, and
- Balance a shoulder mounted camera system by acting as a counter weight.
Since this brick won’t directly plug into (or fit into) the camera battery compartment, you need to find a way to physically attach this thing to a camera or rig.
For this reason, the battery is mounted on a battery plate or bracket or mount:
The bracket is screwed on or slid into (if there’s a matching connector) to the rig. Every time you need to change the battery you don’t need to bring out the screwdrivers. Also, when a battery dies for good, which it will at some point, you don’t need to pay for the plate again. Metal plates with gold connectors are not cheap.
This methodology also allows a battery manufacturer to produce standard batteries and different brackets for different cameras. A race car changes tires depending on track conditions – you don’t change the whole car every time you need to change tires! This is a truly modular system, where each part not only complements each other, but together they do more than the sum of their parts (a synergy).
Sometimes the bracket can also charge the battery (optional; only used under certain conditions):
Now that you have batteries, you’ll need a charger to charge them:
The bigger the battery, the more time it takes to charge them (all other things being equal). Therefore, on a professional battery system, it is wise to have a dual (space for two batteries) or quad (four batteries) charger that can charge all batteries plugged in at the same time.
Ways to connect the system to your camera and gear
A camera has a certain size and type of DC connector. An external monitor or viewfinder, etc., might have different connectors; not to mention different voltage requirements.
Leaving aside the voltage bit, how can one battery be connected to different devices with different connectors? Simple, we need a standard connector (like XLR for audio and SDI for video) that everyone can adapt to. For this reason, professional battery systems have what is called a Power tap or P-tap or D-tap connector, from which you run a cable that connects to your camera.
Let’s start with the camera first, the most important part of the rig. Usually, a battery mount is custom-made to fit the DC port of your camera, like this:
Each mount also has one or more P-taps or D-tap ports. To connect your devices to the mount, you can buy (sometimes free with your device) adapters based on the voltage and size of your devices’ DC ports:
The above has a voltage regulator to power a Blackmagic Cinema Camera. Some devices are fine with the voltage provided directly from the battery:
If the number of P-taps are limited, and you want to add that ‘one more thing’, then you can split P-taps to power more devices:
It is designed to provide a uniform voltage across all taps, but that might not always be the case.
The P-tap forms a standard at the battery end. At the other end (the device), you have multiple options like DC, XLR, LEMO, another P-tap, etc. There are adapters for all kinds of connectors, like this one for example:
Some battery manufacturers make direct converters with voltage regulation built in, but no manufacturer can account for every device out there. To convert DC voltages, you’ll need something that’s called a buck-boost converter. Take great care, as an error here will destroy your gear. If you don’t know what you’re doing, don’t do it.
Let’s recap. A battery system has:
- Mount with P-tap connectors
- Cable adapters that connect to the P-tap connectors
- Splitters (optional)
- Voltage Regulators and buck boosters (optional)
If you need to upgrade batteries, you can, without changing everything else. The charger can take many kinds of batteries, too. When you change your camera, all you need to do is change an adapter cable and maybe the voltage. As we saw in the first table in Part One, most cameras have a safe voltage range over which it can operate, so you have some leeway.
A typical battery on a broadcast camera helps it become ‘center-back’ heavy. A smaller, lighter battery does not provide for much support.
If you’re using DSLRs and nothing else, one piece of gear to consider is the vertical battery grip:
This fits at the bottom, and comes with two trays – one for the original battery and another for 8 AA batteries. The battery grip is more of a photographer’s necessity, but it has the advantage of taking another battery if you have no other recourse.
I always recommend using the grip the manufacturer provides.
How to find the ideal battery system for your gear
Ideally, the battery system should:
- Power other devices on the rig
- Balance the front-heavy load of the camera and lens
- Provide a constant voltage for as long as possible
- Be rugged enough to withstand the production environment (temperature, heat, shock, etc.)
- Come with a fast robust charger
Don’t take the ‘power other devices on the rig’ too literally. Sometimes it’s just not possible to power every device with one battery system. Sometimes, as we shall see, it doesn’t make sense. and it might be simpler to keep track of different batteries than troubleshooting electrical problems on set. Remember, a set is a place to tackle creative problems, not technical ones – create a system that is easy to fix and control, and you’ll be most productive. Doing things in a convoluted way might seem cheaper and smarter but you’re really shooting yourself in the foot.
I also am a firm believer of the battery being a device that balances load on a shoulder rig. If your spine isn’t that valuable, no worries. If you are smart, you can spend a few days designing the perfect rig for your body type and save yourself years of pain and medical bills later.
Having said that, just because heavy battery systems balance out a camera rig doesn’t mean you should get one. The rule of thumb I would follow is: Only opt for heavier battery systems if it simplifies your power needs. If separate batteries are good enough, don’t get a heavy system just to balance out a rig. Rationale? A heavy battery is just dead weight anyway in this particular case, so why spend money for an expensive dead weight when you can just buy weights!
To find the ideal battery system for your gear, follow these steps:
- Make a list of all the items in your rig that need external power.
- Prepare a table of power draws, voltages and ampere draws, as I have shown. Sort it from high to low or whatever.
- Against each device note down the kind of connector it uses to draw power – is it a DC jack, XLR or LEMO input, USB, or custom port?
- Look at the battery systems you are interested in and figure out how many devices it can support.
- Imagine scenarios where you might have to add or remove devices on the fly – is the system capable of being adapted conveniently? Don’t forget to factor in special setups and circumstances. Is everything portable? Is this the simplest setup possible?
- After filtering down your list you will be left with a few options, or at least one option. If you don’t have any options you’re expecting too much and you might want to rethink your ideal battery size (as I’ve shown earlier) and find the systems that provide the exact Wh or mAh that you need for your rig. You can always have two systems or more if the situation warrants it.
- Stick to the manufacturer that offers the best value for money and service. Consider the manufacturer’s pedigree in video. When in doubt, choose the more conservative option. Price should be your last consideration.
If you do everything right, you’ll be blessed with a flexible battery system that will last you through many cameras and productions. To complete this guide, let’s look at a real-world example. Be sure to read to the end, though, because it’s a roller coaster ride!
Battery system for the Canon C300
For practice, let’s see how we can build a battery system for the Canon EOS C300. The Canon C300 needs 11.7 Watts, so for every hour we’ll need to supply the camera body with 11.7 Wh of juice.
I like my battery to have 4 hours worth of juice, so I’m looking at a battery with capacity of 46.8, or roughly 50 Wh (about 5,500 mAh).
Now, I want to use the following devices with my camera:
- AJA Ki Pro Mini Recorder
- Marantz PMD661 Portable SD Recorder
- Marshall 9″ V-LCD90MD Monitor
- Cineroid Pro EVF4RVW
- Sennheisser ME66/K6 Shotgun microphone
- Senneheisser G3 Wireless lavalier Kit
For simplicity’s sake, I’m neglecting the power drawn by the lens for Image Stabilization, Autofocus, etc.
This rig of mine is lightweight but of professional quality. On the field I use the viewfinder on the camera, a 20″ Panasonic monitor and record to the internal 50 Mbps 4:2:2 codec. But let’s complicate matters a bit.
I have a major choice to make – separate batteries or one battery system?
Here’s a chart showing these components with their power draw, voltage and connector type (Click to enlarge):
I have also listed one ‘recommended’ battery for each device, though it might not be the ideal one in a standalone scenario. E.g, the Canon LP-E6 battery is common between the monitor and EVF, so I’ll only have to get one charger if I’m going that route. The ‘better’ option is the BP-911 or BP-915.
The C300 has four battery options, of which I’ve listed two. The best option is probably the BP-970G, which gives about 5.8 (5 hours and 48 minutes) hours.
The first thing I look for are the things I can’t control. The Ki Pro mini has no option for batteries, so it’ll need an external battery system supplying power to it through its 4-pin XLR port. If I’m forced to use a brick, I might as well power the camera with it, too.
Both the Marshall monitor and the Cineroid EVF has the same option, of being connected to the brick, so why bother with the LP-E6 or any other battery system?
It becomes pretty obvious that all the four devices can be powered by one brick, and that would be the most convenient option, as long as the budget doesn’t play spoilsport.
What about audio? The Marrantz will provide phantom power to the shotgun mic, so that’s covered. The G3 can only take AA batteries, and is connected to the Marrantz via a 3.5mm jack. The recorder itself has a DC jack with a voltage rating different from every other component already on the brick. For this reason, I decide that the audio solutions will have its own power. I’ll get 5 hours with AA batteries anyway, and I’m covered. I can always go to the nearest store and get more AA batteries if I’m in trouble.
Therefore, I decide to use rechargeable AA batteries for my audio gear. I’ll carry a bunch of alkaline spares just in case.
Putting together the system
So, we’re gaining speed now. The total power requirement of all the devices (except audio) is 47.6 W, or about 50 Watts. With a 50 Wh brick I’ll get one hour. For 4 hours I’ll need a 200 Wh brick.
Oops. Speed kills.
Anton Bauer makes a line of high capacity batteries called the Cine Series, but that’s overkill, not to mention huge for my particular rig. The best option I have is the HCX with 124 Wh. I’ll get 2 hours with it.
It looks like I need to either break my own four-hour rule. Back to the drawing board.
One way to improve our ‘situation’ is to run the monitor on its own battery. I could use a BP-970G, which will give me 4 hours. The same battery will also power the C300 if necessary. If I go this route, what’s the improvement I get? Another hour, on average. Is that worth the trouble of juggling two battery systems?
Not for me. I’m already paying for the Anton Bauer, so why not stick to it? So, 2 hours it is. To reliably run this system, I’ll need at least 6 Dionic HCX bricks (12 hours worth) and if I’m following my own 24-hour rule, I’ll need 12.
Six batteries is about $3,500 at the time of this writing. To charge these bricks, I’ll need a dual charger, the Anton Bauer Dual 2722 Charger. It will also give me 70 Watts of supply when connected to the mains.
The compatible gold mount plate for the C300 is the Anton Bauer QRC-CA940:
This gives me three Power tap outputs – one for each of my three devices. We’re looking good:
To connect to the monitor, I use the free Marshall Power tap to XLR adapter. For the recorder, I opt for the Power tap to XLR adapter from Anton Bauer. The length depends on the rig, but usually I go for 3 feet (the maximum). This gives me the greatest flexibility if I want to place my monitor, recorder or EVF further away for some reason. The Cineroid comes with a free D-tap to mini-XLR adapter so I don’t need to buy anything extra.
Here’s the final list:
- 6x Dionic HCX bricks – $3,500
- 1x Dual 2722 Charger – $1,200
- QRC-CA940 Gold Mount – $330
- 2x Power Tap to XLR adapters – $130
- 1x Power Tap to mini-XLR adapter – $75
I have two additional adapters just in case the ones provided by the manufacturer fails.
Total? $5,235, or about one-third the price of my camera body. Is it expensive? Of course. Is it worth it? You bet.
Let’s consider another possibility: What if we eliminate the Ki Pro Mini?
One battery at full charge will power both camera and monitor for 1.75 hours (1 hour and 45 minutes). That’s similar performance to the HCX! I could buy 8 of these for only $1,160, and a couple of Pearstone Compact Chargers for $60. To power the Cineroid, I could use the same charger or the Dekcell Camcorder Battery Charger to use BP-911 batteries, since that mount comes for free with the EVF package.
I could put together a fully functional battery system without any cables for less than $1,500. $1,500 or $5,000? You decide:
How much are you earning from your productions?
Are you changing rigs often?
Do you own many cameras and types of gear?
Are you often working under tough conditions with a minimal crew?
Are you comfortable juggling many batteries and keeping tabs on charging them?
Is luggage weight a concern? Do you have to trek for hours?
What do I use when I rent the Canon C300? The Canon batteries of course. I don’t need the Anton Bauer setup for my workflow, because I don’t use an external recorder or a small external monitor.
I hope this example has given you ideas on how to assemble the right battery system for your production. Sometimes the choices are not that cut-and-dried, and this is when you need to find a quiet corner, sit down and follow the steps I’ve outlined above.
In no-time you’ll have a system you will be happy with, at least on paper.