Video Batteries - Keys to Top Performance
Today’s broadcast and cine batteries are compact and powerful, allowing them to meet the combined load of both camera and accessories.
As any photographer or camera assistant will confess, a dead or dying battery during production quickly becomes a crisis. To avoid the predicament and maintain top performance from your kit of batteries here are some tips.
On any remote shoot, an adequate and reliable power supply for cameras and other gear should never be taken for granted. Tally up the power needs. Is there sufficient battery capacity to power all the gear? Batteries can be affected by temperatures, usually resulting in faster discharge rates. Is the battery pack sufficiently sized to go the distance, even in the most remote locations and extreme conditions? Are they being charged properly and used safely? And how easy will it be to get them to and from the shoot. If the crew is going by air, first read the latest IATA regulations for air transport of lithium-ion batteries.
As basic as power systems might seem, their proper use and care can mean the difference between success and failure for an entire shoot. In this article, we’ll explore best practices for getting maximum use out of today’s state-of-the-art broadcast and cinematic batteries – including power requirements, charging, safety, and transportation tips.
What’s Your Power Budget?
The amount of power you’ll need – and the battery type – depends on the production, the type of camera being used, and the additional gear that needs to be powered. A typical broadcast camera, say for ENG reporting from the field, is a lean-and-mean setup with few additional accessories (save an RF system for transmitting video or a top-mounted light).
A larger shoulder-mounted broadcast camera will typically require in the neighbourhood of 40 watts. Anton Bauer believe batteries targeted to the broadcast market should be rated at 10 amps of continuous current (and therefore 144 watts), which is more than adequate for most broadcast cameras and their accessories.
On the other hand, a cinematography setup is generally much more power-intensive. A top-flight digital cinema camera, such as the ARRI ALEXA SXT, might need upwards of 110 watts for its own operation, and then you have to consider all of the other power-consuming devices that will be feeding off the battery – monitors, recorders, lens motors, cinetapes and more. With a camera system like this, more power may be required than a standard on-camera battery can reliably deliver.
Video camera batteries often must power multiple accessories. Be sure you include the requirements of such devices when calculating power needs.
Consider also the latest breed of lightweight LED lighting fixtures. While they are a boon to on-location shoots because they can be powered from the camera batteries, they also need to be accounted for in the power budget.
In both of these situations, it’s best to use cinema-style batteries that are rated to deliver 12 amps continuous and at least 174 watts, offering an additional 30 watts of headroom for extra gear in complex setups of the latest generation of high output LED fixtures.
Types of Battery Mounts
It might seem fundamental, but we actually do get asked fairly often to explain the difference between the V-Mount and Gold Mount battery mounting systems. Gold Mount was the first truly universal battery mount, designed so that the battery bracket could be fixed to any type or brand of camera. Gold Mount uses a proprietary communications protocol that enables the battery to exchange percent-charged information with the powered device.
Anton Bauer Gold Mount battery plate.
Gold Mount batteries also work as a seamless unit with compatible chargers to ensure optimal and safe charging and maintenance. On the other hand, the V-Mount uses a standardized, open-source communications protocol that enables easy communication with a wide variety of devices, but it may also limit the types of communication that can take place.
Other key differences: While almost every camera can be adapted to either mounting format, Gold Mount batteries are dominant in North America – while V-Mounts are almost universal in Europe. V-Mount batteries mount from the top down, and Gold Mounts attach sideways, something to consider in a space-constrained situation where you might have more overhead room than side room, or vice versa.
V-Mount plates get their name from the large “V” capture groove on the back of the battery mount.
Prolonging Battery Life
Appropriate charging is another critical area that can’t be overlooked when working with broadcast or cinematic batteries. Batteries need to be ready to go with a full charge when they are needed. But, they also must be protected from overcharging and other abusive charging practices that can cut a battery’s life in half.
Therefore, it’s important to make the right choice in a battery charging system. While a budget charger might save the production money, the typical low-cost charger only does one thing – apply voltage until the battery can’t soak up any more energy. An intelligent charger, on the other hand, manages cell voltage and current draw actively to prevent overcharging or cell overheating. The better chargers will utilise proprietary algorithms that move through up to multiple distinct charging phases, with the last phase being a maintenance mode.
Users should store their batteries on an intelligent charger that will maintain constant communication with the battery to ensure that the voltage level of the cells stays within an optimum range. An intelligent charger also monitors external environmental factors, such as air temperature, to help the battery adapt while protecting the cells from heat damage.
Lithium-Ion battery chemistry is here to stay in the media and entertainment industry, because it offers the highest energy density and best performance. But are lithium-ion batteries safe? The answer is a resounding “yes,” if the batteries are handled correctly, and if they are manufactured by a reputable vendor that has taken care to design safety into the battery’s internal construction.
This Anton Bauer battery illustrates some safety features to consider in battery construction. Safety features in this battery include; a protection crush zone around the cells, which also promotes cooling airflow and a case made from high-strength ABS/PC material.
Before choosing your production’s power source, make sure to understand the battery’s safety features. In order to deliver the power and voltage needed for media applications, the typical broadcast or cine battery can bundle up to 24 Li-cells in a single pack.
This high density requires that the battery have a second level of safety design, one that will prevent individual cells from interacting with each other and igniting should one cell become damaged. Some batteries, for instance, feature a “double-skinned” architecture, in which the cells are individually contained in an impact-resistant, flame-retardant plastic honeycomb. A built-in air gap between cells further ensures cooling air circulation in the pack and that no cells can touch each other.
The Skinny on Transportation Regulations
Thanks to some isolated but high-profile incidents, involving Li-ion batteries, have led to some batteries being classified as hazardous cargo by the International Air Transport Association (IATA). The IATA and FAA now mandate that Li-ion batteries and cell packs need to be discharged to 30% of their rated capacity before they can be shipped as air cargo. And even then, that cargo may not travel in the hold of a passenger aircraft.
However, batteries charged to 100% can go in the cabin in carry-on luggage as long as they meet certain restrictions (just as with laptop batteries). For batteries with capacity less than 100 Watt hours (Wh), the IATA places no limit on the number that can be carried per passenger. It is always wise to check with the airline because some may impose even tighter restrictions.
For batteries rated between 100 Wh and 160 Wh, regulations stipulate that a passenger may carry one battery on a piece of powered equipment plus two spares. Batteries greater than 160 Wh may not be carried on and therefore must be shipped as cargo.
Of course, these regulations have a profound impact on users, because media production professionals are among the most frequent travellers in the world. Every week we hear from customers who have had their batteries confiscated – either because they weren’t up to speed themselves on the regulations, or because the gate security personnel were not properly educated. The best you can do is to arm yourself with the facts; know the regulations inside and out, and also make sure you understand the airline’s own rules, which are often even more stringent than those of the IATA.
To help combat this confusion, the battery industry is responding with dischargers. The automatic discharge function is typically provided as a function of a battery charger. The discharge mode will automatically drain batteries to the proper level for shipping. And on an even broader level, manufacturers are working together to lobby the regulatory bodies to make sure restrictions are only in place where it truly benefits the safety of all involved.
Conclusion – It’s All About Power
The bottom line is that the appropriate and effective use of Li-ion batteries really isn’t rocket (or battery) science. It really boils down to three things: ensuring power delivered and battery capacity are in line with the production’s requirements, effective charging and battery management to get maximum life and performance from the battery, and knowledge of safety rules and regulations. Keeping these factors in perfect balance can make powering a production one of the least worrisome aspects of your job.
Andrew Butler, Product Manager, Anton/Bauer
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