There are a number of battery technologies on the market for professional video equipment, and choosing the right power for your equipment in the field has become more complicated than ever. NiCad, NiMH, Li-Ion, and other options--what's the best solution?
How about all of the above?
"Actually, they should buy some of each," recommended Alex DeSorbo, president of Anton/Bauer. "The reason is that different chemical formulations of batteries offer different benefits, all of which can be useful to a videographer in the field. For instance, nickel cadmium (NiCad) and nickel metal hydride (NiMH) batteries are heavy cells that can deliver a lot of long-term power, and have the flexibility to support the extra wattage demanded by camera lights. These are the sort of batteries you want on your camera.
"For backup power, you want to tuck a lithium ion (Li-Ion) battery into your pocket," he continued.
"Although it doesn't have the same wattage flexibility and takes longer to charge than nickel, Li-Ion batteries weigh 50 percent or less than comparable NiCads and NiMH batteries."
If all this seems as clear as mud, then perhaps it's time to explain the functional differences between NiCads, NiMH, and Li-Ion batteries. We'll stay clear of the specific chemistry--suffice to say that all three types of cells create power through internal chemical processes which produces electricity.
Charging a battery doesn't put the power back; rather, it reverses the chemical process that produced electricity in the first place. This explains why batteries produce less power in cold temperatures; cold slows down the chemical reactions that generate electricity.
NiCad and NiMH batteries belong to the heavyweight class of batteries. They're the traditional workhorses of the ENG/EFP industry, the weighty bricks that sit on the back of camcorders worldwide.
"Both NiCads and NiMH can handle a wide range of power loads," said Jim Crawford, president of Frezzi Energy Systems, which produces a variety of battery types. "Their weight can also be a plus if you are using a full-sized camcorder and need some counterweight at the rear to counterbalance the lens."
One point worth noting: Although NiCads are cheaper than NiMH batteries, they don't offer as much battery life. "A typical professional NiCad on-board battery will deliver up to 75 watt-hours, whereas the same in NiMH will get up to 130 watt-hours," Crawford explained.
In contrast to NiCads and NiMH batteries, Li-Ion batteries are lightweight and compact. The downside is that they don't have the same ability to support a wide range of loads. In other words, if you ask a 90 watt Li-Ion battery for 120 watts of power, it won't be able to do it.
Li-Ion batteries were originally developed for laptop computers, a sector where a constant power supply built into a small package is top priority. Because laptop users rarely mount camera lights on their computers, Li-Ion batteries aren't designed to handle such extra loads on demand.
"The primary advantage of lithium ion is its power-to-weight ratio," said Barry Rubin, general manager of IDX. "To get 90 watt-hours, you can use a 1.5-pound Li-Ion battery, or a 4 to 5-pound NiCad/NiMH battery." Anton/Bauer's DeSorbo agreed: "If weight is your top priority, then you should choose lithium ion."
It's worth noting that IDX has developed a product called "PowerLink," which lets users connect two Li-Ion batteries in parallel. The result is a 130-watt power supply that has a 160 watt-hour rating, said Rubin.
If you're going to be shooting outdoors in a range of temperatures and power requirements, then NiMH and its long operating life is your best choice. But if cash is tight, use NiCad instead, bearing in mind that you'll need to carry a few more spares in the truck.
Li-Ion can be used in cold temperatures, too. Rubin said they'll show a power drop at initial startup, but will regain about 80 percent of their rated capacity. In contrast, he said, nickel batteries can lose up to 40 percent of their generating capacity in cold weather.
If temperature isn't a big issue and your power requirements will be relatively steady -- and you're using a DV camcorder or other lightweight unit -- then Li-Ion batteries are fine. Sure, they can take 3.5 hours to reach a full charge, compared to the hour or so need by today's NiCads and NiMH batteries, but "they will reach an 80 percent charge in around 60 minutes," said Rubin. If you've left enough head room on your power requirements by buying high-capacity Li-Ion batteries, then you could be OK with an 80 percent charge in most situations.
If long-term battery life is an issue -- you don't have the budget to buy new batteries every year -- then you would be safer with NiCads and NiMHs. "A NiCad or NiMH battery is like a V-8 engine that runs at low revs, while a Li-Ion is akin to a four cylinder running at high revs all the time," said DeSorbo. "Clearly, a V-8 will last longer than a four cylinder."
If you want the ability to charge your batteries in the car, then purchase a DC-to-AC power inverter. These units plug into a car lighter socket (more powerful inverters must be connected directly to the battery); just plug your charger into the inverter's three-pronged outlet, and you can top off your batteries while you drive.
Something Completely Different
If you're tired of the whole battery charging game, then you could break out of the mold and switch to hydrogen fuel cells. Jadoo Power Systems' NABII fuel cells come in a brick-style unit that fits on most camcorder battery plates. Simply connect the 4.7-pound power converter to the plate and slip in a 2-pound. soup can-sized hydrogen fuel. You now have a 60-watt (peakable to 75 watts) source that can run up to 145 watt/hours of power, according to Larry Bawden, Jadoo president and CEO.
When one canister is depleted, you just pop in another. As for recharging, the Jadoo Power System comes with a four slot Refill Station that uses hydrogen drawn from a standard commercial cylinder. Bawden estimated the cost of hydrogen for a year's use of the NABII system is less than $50.
Unfortunately, the word "hydrogen" tends to conjure up images of the ill-fated Hindenburg; the hydrogen-filled zeppelin that exploded spectacularly before U.S. newsreel cameras in 1937. However, it now appears that hydrogen got an undeserved bad reputation from this disaster. According to the U.S. Department of Energy, research from former NASA scientist Addison Bain and German scientist Ulrich Schmidtchen indicates that the fire was a result of chemical and electrical properties of the outer shell's paint, not the hydrogen.
"Jadoo stores hydrogen the same way a NiMH battery stores hydrogen as a solid in a metal hydride," explained Bawden. "The NiMH battery is really a nickel hydrogen battery where the hydrogen is stored as a solid that makes it safe."
To back its contention that hydrogen is safe, Jadoo has obtained an exemption from the Department of Transportation to ship these cartridges by cargo aircraft. "Independent testing proved the safety of Jadoo's fuel cartridges, even when they were thrown into a bonfire, and this is the reason the DOT gave us this exemption," added Bawden.
The risks associated with a hydrogen leak are actually less than with other commonly-used gases. "Hydrogen is much lighter than air," Bawden said. "If some should leak, it will disperse very quickly. Hydrogen is much safer than propane, which hovers close to the ground due to its weight."
Clearly, no one battery is perfect for all needs. Before you buy, it is imperative to analyze your own requirements and choose accordingly. That said, NiMH batteries are a strong option if you afford them. Not only do they deliver similar yet superior performance to NiCads, but they are a much better environmental choice (cadmium being a particularly nasty chemical).
However, don't ignore Li-Ion batteries: It makes good sense to have a pocket-sized backup power supply, and in some cases Li-Ion can be viable as a main power course. As for hydrogen fuel cells, they are worth a look, and broadcasters such as KOVR in Sacramento, CA, have already started using Jadoo's hydrogen power system.
Frezzi Energy Systems
Jadoo Power Systems
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