How the Anton Bauer Cine Line Delivers High Power Output with Safe Design Principles
With respect to camera batteries today there are two main challenges facing shooters and production facilities:
- having sufficient high-capacity batteries to keep our power-hungry cameras running
- proper maintenance, charging, and transporting, of the larger lithium-ion battery packs.
The latest-generation large-sensor cameras are serious power hogs. The Arri Alexa, commonly used in high-end cinema production, can easily draw 100W or more when fitted with a Teradek wireless system, follow-focus, lens control, and on-board monitor. Likewise for the various Red models, Panasonic VariCam, and Sony F5/F55, all of which are only slightly less voracious consumers of power. Regardless of manufacturer, with every new camera model, the thirst for more amperes grows along with the increased processing loads.
It can be expensive, not to mention a significant hassle, to provide enough high-capacity batteries. Most camera batteries from Anton Bauer and other leading industry manufacturers were designed for small-format ENG cameras drawing a maximum current of 9A–10A. Today these batteries lack the capacity to power systems like the Alexa that require a constant 12A for the camera, along with the typical Christmas tree of accessories.
Providing 12A of constant power, Anton Bauer’s new Cine series batteries are specifically designed for high-draw cameras. The economic and practical stakes are high — a typical Alexa package ships with eight 120/150Wh batteries, each capable of running the camera and peripherals for approximately one hour.
The Cine series’ boxy shape cleanly accommodates the typical Christmas-tree array of umpteen cables, plugs, and boxes adorning today’s production cameras.
While providing sufficient battery power to the camera is mission-critical, cinematographers and filmmakers are also facing related challenges with respect to air transport. On a recent feature project in Japan, my Los Angeles rental house encountered serious problems attempting to ship two dozen high-capacity lithium-ion camera batteries to Japan. Because the palette had to be treated as hazardous cargo, the shipment incurred significant costs and delays that impacted production. The new IATA rules in effect as of April of this year imposed new, even stricter requirements on the transport of lithium-ion batteries on aircraft. The higher capacity batteries productions require these days only contribute to the hassle and expense of transporting these battery packs by air.
The potential dangers of lithium-ion batteries are well documented and recognized by the public, as evidenced in a recent YouTube video of a hoverboard engulfed in flames. A lithium-ion battery pack exploded, likely due to the lack of built-in battery protection and the high heat accumulated from overcharging. Lithium-ion fires have brought down jetliners and destroyed camera rental and television production facilities, so due caution should always be exercised in the handling, managing, and transporting of larger lithium-ion battery packs.
Lithium-ion batteries realize their high efficiency via a potent chemical reaction. It is not derived organically, as in the case of safer but less efficient nickel metal hydride (NiMH) cells. This is a key consideration. A lithium-ion battery may discharge in a slow trickle over time or in a moderate, more controlled way as in the normal running of a camera, or in an instantaneous release of energy that can result in an explosion or fire. Such a fire might result from an internal short circuit, or the battery could be overcharged with damaged seals or physically damaged in some way. But once a cell goes thermal, there is no extinguishing agent that can stop it. As each cell breaks down, it fuels the next explosion in an adjacent cell. Today’s high capacity lithium-ion batteries with many cells have an even greater potential for a devastating explosion or fire so proper design and care of the larger battery packs are especially critical.
In actual practice, such incidents of fire or explosions in properly designed batteries are virtually non-existent. Take Anton Bauer. The company claims that not a single one of its professional camera batteries has ever caught fire outside of its own carefully controlled laboratory tests. The company explains that the batteries are made inherently safe by maintaining physical space between cells. Moreover, the cells cannot be over-discharged. The Circuit Interruption Device built into each cell is pressure-sensitive, so if the heat and pressure rise excessively — say, from over-charging or over-discharging — the CID will trip and shut the battery down, limiting any fire hazard to the one affected cell.
The typical lithium-ion battery is like a pack of firecrackers. If one cell catches fire, the adjacent cells will also ignite. Some lithium-ion battery designs feature a separation between cells and a honeycomb structure to prevent thermal runaway.
Battery designs that pack the cells tightly against each other may increase the odds of a fire or explosion in the event of a single overheated cell.
To avoid over-charging or over-discharging the proper smart charger is imperative.
Over-charging a battery drives excessive voltage into the cells, destroying the inner seals and greatly accelerating the aging process. It also increases the risk of the lithium-ion chemical reaction running amok and sparking a thermal runaway.
For maximum safety and long life, a camera battery and its charger must be in constant communication. For example, Anton Bauer systems continuously monitor the state of the battery, so once a battery reaches 100% the charger effectively shuts down to prevent overheating. As the battery discharges naturally over time, the charger becomes aware and initiates a small trickle charge to maintain full capacity. The charger monitors temperature, cell voltage, and the charging interval; save for this communication, 99% of the time nothing is happening between an Anton Bauer battery and the corresponding charger. Shooters, television networks, and production facilities must understand that a battery can only retain maximum capacity when attached to a charger that understands and can respond to its actual present state.
For longest life and maximum capacity, a professional camera battery should be cycled through at least once every two months. When not in use, the best place to store a battery is connected to a charger that continuously monitors the health and state of the battery. Beyond four years, most camera batteries, regardless of type, will fall below the 70% capacity threshold and will likely need to be replaced.
While exploding hoverboards and cell phones seem well removed from the world of professional camera batteries, high-profile consumer incidents like the hoverboard fire can have a significant impact on how we operate and conduct our craft. Indeed, the hoverboard debacle seems to have prompted the IATA to adopt even more stringent restrictions on the transport of lithium-ion batteries in commercial aircraft.
This recent YouTube video of a Hoverboard catching fire (the action starts at about 1:50 in) drove home the potential peril of cheap lithium-ion batteries in consumer devices. Lithium-ion batteries can be especially hazardous aboard aircraft as superheated debris thrown off by burning cells can and has melted through the walls of aircraft cargo holds. The flames from a camera battery experiencing thermal runaway can shoot 10 feet into the air at a temperature of over 1000 degrees Fahrenheit!
As of April 1, 2016, lithium-ion batteries (regardless of capacity) may not be placed in checked luggage, unless they are attached to the piece of gear for which they are intended. Yes you can put your cell phone, beard trimmer, and Bluetooth earpiece in your checked bag, along with your Sony FS7 and affixed lithium-ion battery. This is allowable because the battery is attached to the device.
But additional lithium-ion batteries must be carried onboard. The number of carry-on batteries with a capacity of 100 watt-hours or less is subject only to the normal carry-on restrictions imposed by the airline. In addition, the battery contacts must be taped. Lithium-ion batteries over 100Wh capacity, up to 160Wh, may also be carried aboard but are limited to two batteries per passenger.
In April the IATA also adopted new regulations pertaining to the shipping of lithium-ion batteries. Lithium-ion batteries transported as cargo or in checked luggage cannot now exceed 30% of charge. From a practical perspective, the rule seems mostly aimed at manufacturers like Panasonic, Tesla, and Anton Bauer, and also some rental houses who ship large quantities of lithium-ion batteries in single shipments. The IATA rules apply to shipping via commercial aircraft and sea vessels only. The rules do not apply to private or chartered aircraft. In these cases the conditions of carriage are, as before, at the discretion of the pilot.