Video Batteries: A Long Journey from Very Basic Cells to a Complex Mix of Chemistries

When RCA introduced the TK-76, the first broadcast-quality portable handheld video camera in 1976, the standard batteries included with the camera were Cine 60 nickel cadmiums (NiCd). Battery life for this power hog camera on a NiCd was about 20 minutes, which meant for a day of shooting it took a very heavy bag of expensive cells — each weighing several pounds.

Anton/Bauer photo of inside of a Li-Ion battery

Early NiCd batteries had a lot of problems. They were made of very toxic chemicals. They developed a memory effect, requiring “exercise” to prevent memory problems. The batteries had a high self-discharge rate and required frequent charging with very unsophisticated chargers that could easily damage the battery by overcharging it. They would lose their charge even after only a couple days of storage. Cheap chargers did in all the NiCds being used for daily professional use in a very short time.

NiCd batteries became such a problem in the field that Anton/Bauer, a leading battery company, released in the late 1970s a very expensive and delicate alternative battery called the silver cell. It had a very high energy to weight ratio. Two silver-oxide cells would run the RCA camera all day.

But silver cells were very expensive — at least $1,500 each plus a very sophisticated charger. The cells had to stand exactly upright or they would fail. Silver cells were so advanced they went to the moon, powering the Apollo lunar module.

Rapid advances in battery-manufacturing technologies throughout the second half of the twentieth century made cells increasingly cheaper to produce and far more reliable in operation. NiCd batteries began to be overshadowed with more efficient technology after the mid-1990s.

Nickel–metal hydride (NiMH) batteries are higher in density, mostly free of toxic materials and less prone to memory effect than rival NiCds. They have a 30 to 40 percent higher capacity than NiCads, but require more sophisticated charging technology. They are about 20 percent more expensive than NiCad technology.

Today, NiMH has mostly been pushed aside by Lithium Ion (Li-ion) chemistry, now the fastest growing battery technology. It is used where high-energy density and light-weight is of primary importance. It has a low self-discharge — less than half that of NiCd and NiMH. It is a low maintenance battery and needs no periodic discharge to protect it from memory issues.

Li-ion is especially useful now that power requirements on video shoots has increased. Some crews not only power the camera, but monitors, LED lighting and other accessories off the same battery.

On the negative side, Li-ion technology is a bit fragile and requires a protection circuit to limit voltage and current to assure safety. If not “provoked,” the battery is generally considered safe. It should be stored in a cool place and at a 40 percent state of charge to reduce the aging effect.

Li-ion batteries are expensive to manufacture, costing about 40 percent more than NiCd technology, though prices are falling due to better manufacturing techniques.

The federal government restricts Li-ion batteries for air travel. Generally, batteries 100 watt hours or less can be carried on-board airplanes in unlimited quantities. For Li-ion batteries 101 to 160 watt hours, a maximum of two batteries may be carried on and an additional battery installed on equipment. Li-ion batteries over 160 watt hours cannot be transported at all by law. There are no travel restrictions for NiMH batteries, which has kept the technology alive.

Graham Sharp, Snr. VP

Graham Sharp, senior vice president, product management and engineering at Vitec Videocom, which owns Anton/Bauer in Shelton, Connecticut, predicted that Li-ion is the battery chemistry that will be powering the video industry for the next five years. “It provides the best performance available today as it has a very high-energy density, is reasonably priced and is safe if handled correctly,” Sharp said.

The safety issue with Li-ion is not that it is inherently unstable, but that it can burn without external oxygen. Once on fire, it is hard to put the fire out since most methods of extinguishing fire involve removing the external source of oxygen.

Typically with Li-ion technology, the anode, electrolyte and cathode are constructed in thin layers and then rolled to create a cylindrical canister, often the size of a AA battery. Before a cell can be released to the market, it is tested both physically and electrically.

The cell is crushed, pierced, heated, overcharged and over-discharged. The battery can only be sold after passing these tests in quality control. Thus, a single cell is considered safe.

It’s the grouping of individual Li-ion cells with others where problems can arise. Sharp asked battery users to imagine that 12, 16, 20 or even 24 of these individual cells are combined in a battery pack, which is the configuration used to provide the necessary voltage for media applications. A second level of safety design is then required to make sure individual cells don’t interact with each other.

For example, if a battery is accidentally punctured or crushed, causing an anode and cathode to touch, it is not just a single cell that is affected. A fire can consume the entire battery pack.

To toughen its Li-ion batteries, Anton/Bauer uses a “double skinned” architecture where the cells are individually contained in an impact-resistant, flame-retardant plastic honeycomb, with a one millimeter air gap between them. This ensures that no cells can touch and allows air to circulate to keep the pack cool. 

Anton/Bauer illustration of inside a Li-ion battery

The entire cell pack is then “suspended” within an impact-resistant outer case, maintaining a five millimeter air gap around it and providing a “crumple” zone to prevent crushing and accidental penetration of the cells themselves by sharp objects.

Thermal sensors continually monitor the battery, and if a rise in temperature is detected, a switch is opened to prevent further charge or discharge. Similarly the charge and discharge currents are continually monitored, and if too much current is flowing, the battery switches off.

Another major battery manufacturer is Frezzi Energy Systems, a company based in Hawthorne, New Jersey that has been making batteries and lighting gear for more than 70 years. Frezzi has just announced its new Eylight, the first professional video camera light that includes an internal plug-in Li-ion battery that powers the 75-watt LED fixture for two hours. It’s the first video light integrated with a battery.

Frezzi 200 watt Li-ion batteries and charger

Frezzi makes two types of Li-ion camera batteries today — a 100 watt hour model that’s legal for air travel and a 240 watt hour model that cannot go on airplanes. All Frezzi battery packs work with both Anton/Bauer or V-Lock battery brackets.

Jim Crawford, president of Frezzi and an Emmy Award winner for pioneering advanced batteries and chargers for television, said virtually all of his company’s research is now going into Li-ion batteries. 

James Crawford (center), president of Frezzi

“In terms of your everyday professional news photographers, it’s all lithium today, Crawford said. “And that goes for the entire battery industry, not just for us. I’d say 90 percent of all business is now lithium.”

Crawford said users just have to be careful when operating with Li-ion batteries. “Professionals know what to with travel restrictions these days,” he said. “The Department of Transportation doesn't want anything packed into luggage. You can’t even put your lipstick in there today. It all has to be in the carry-on.”

Though lithium technology now dominates the industry, Crawford said his and most competing companies still make NiMH batteries for those who need them. “We make a 150 watt hour nickel metal hydride battery and you can travel with those,” he said. “There are certain customers that still use those types of batteries.”

The trend toward DSLR video cameras has widened the battery market to the makers of the individual cameras. Yet, for running several devices in a professional high power video shooting rig, the major makers of batteries include Anton-Bauer, Frezzi, IDX, PAG, JAG, VECT and, yes, Cine 60.

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