JOE MURTHA /
06.01.2011 12:00 PM
Choosing the right battery
Quality varies, and price shouldn't be the only consideration.

Not so long ago, choosing a battery for your camera was a fairly simple process involving a few offerings from a small number of manufacturers. Today, with new technologies, different chemistries and varying price ranges, selecting a power system for your camera is more complex. It takes some research to find the battery that is not only the best fit for your needs, but also includes the highest quality, reliability and safety features available. Assessing the capacity, load-carrying abilities, charger options and safety mechanisms of today's two main battery varieties, nickel-metal hydride (NiMH) and lithium-ion (Li-ion), will help make this process easier.

Today's batteries vary widely in quality. Therefore, it's important to understand a bit about the manufacturing process so you can weed out the poorly made batteries early in your research. Ask the manufacturer how it obtains its battery cells and builds the battery itself. If the maker is buying standard cells in bulk from wholesalers, chances are its batteries are not well-made, using inexpensive housings and rudimentary electronics. The cost of these batteries may be low, but chances are so will the quality. You have to ask yourself if it is worth it to save a few dollars at the risk of the safety and performance issues you may run into with these batteries.

In contrast, there are other manufacturers of batteries that take more care in their creation, purchasing premium cells directly from well-known cell makers. These cells often come pretested and matched for balance, allowing for longer life. The batteries themselves are precisely crafted in clean rooms, with housings developed to spread impact. Their onboard electronics are of considerably greater sophistication and quality. These tend to cost more but are generally of higher quality and last longer, making them the better investment in the long run.

A battery's capacity, or run time, is a major indicator of quality. Though no battery, even a top one, is immortal, it is fair to say that the better quality the battery, the longer it will last. Look for a battery that includes an indicator depicting remaining run time at a current run load in hours and minutes. The better batteries have these along with access to a test charger, which can cycle the battery and document the results, allowing precise indications of life expectancy.

When reviewing the capacity options of batteries, keep in mind a solid estimate of the average load your equipment and applications draw. For example, if your camera carries 45W and your light 35W, the load will be around 57W. (Fill lights are typically used a third of the time.) Lights feed off power taps, and if your camera cannot regulate this, you should add about 25 percent to your estimate, changing your light load from 35W to 43W. Add into the estimate any other piece of equipment that will need battery power, such as onboard monitors and wireless transmitters. In general, you'll want an average run time of at least two hours so that you don't have to contend with multiple unplanned battery changes, especially in ENG and production applications.

With batteries, the initial start-up creates a spike in power. If, for example, you run a 45W camcorder, a 35W light and 10W accessories, your continuous load is 90W. Check the specs of the battery you are researching to find the maximum continuous load it will support. If this number is 73W, you'll need a battery that can handle a higher load. Some battery manufacturers do not provide these specifications, leaving your power supply to chance. If this is the case, move on to a manufacturer that does have the specs.

The charger should be among the biggest considerations you make when choosing a battery. Look for ones that can last up to 20 years, as these tend to be of better design. If the manufacturer of the battery you're considering claims that it can be used with any type of charger, it's unlikely the design is sophisticated enough for long-term professional use. The battery may even pose a safety hazard. Look for a charger that has two-way communications with the battery and the ability to test and calibrate. It should also have temperature channels and the ability to be upgraded with future algorithms as technology develops.

Safety is the ultimate bottom line when it comes to choosing the best battery for your operations. While NiMH batteries are generally safe, Li-ion batteries are another matter. The Li-ion electrolyte has a low flashpoint and a low tolerance to overcharge, and it can become volatile if over-discharged. Poorly made batteries have a greater chance of one bad cell igniting the entire pack. In the United States, from March 1991 to August 2010, there were more than 100 air incidents recorded involving batteries. Those occurrences prompted the government to issue a total ban on transporting Li-ion batteries over 300Wh and limitations on hand luggage and check-in for Li-ion batteries between 100Wh and 300Wh.

A well-designed Li-ion-based battery will have built-in safety mechanisms. One such example is the honeycomb design, where the individual battery cell is contained in its own housing. This prevents cells that are damaged from affecting undamaged cells, as the thermal heat transfer is minimized. It also protects the person handling the battery by preventing fuel leakage. A beneficial side effect of this design is that it also increases the battery life.

In conclusion, don't choose a battery simply because of its lower cost. As has been noted, manufacturers of low-quality batteries often scrimp on features required for safe and reliable operation. You may end up having to buy more batteries, as poorly designed ones malfunction or don't last nearly as long as their higher-priced, higher-quality counterparts. Also make sure to buy batteries that adequately support your power load. You don't want to lose a crucial shot just because you underestimated the power load.

Choosing a battery for your camera has become a bit more complex due to the wide array of offerings on the market. To take some of the guesswork out of this process, assess the capacity, load-carrying abilities, charger options and safety mechanisms of potential batteries. The more of these features that are present in the battery, the better the battery.

Batteries and air travel

Passenger carry-on
Under 100Wh: Unlimited (attachment on device not required)
Between 101Wh-160Wh: Limit two batteries uninstalled*; additional batteries must be installed on a device
160Wh or more: Forbidden
Passenger checked bagged:
Under 160Wh: Must be installed on device
160Wh or more: Forbidden

*Batteries not installed on equipment must be individually protected to prevent short circuits by placement in the original packaging or by otherwise insulating terminals (tape over terminals, each battery in a separate plastic bag, etc.)

Note: These are Anton/Bauer's recommendations based on IATA regulations. It is recommended that travelers consult the IATA and DOT websites. Li-ion carry-on and check-in are ultimately subject to individual airline and TSA approvals.

Joe Murtha is the engineering manager for Anton/Bauer.



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