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Thursday, June 1, 2006

Gadget Bag: Batteries

What you need to know for reliable power in the field


If you've ever wondered how the flashlight got its name, here's the secret. When flashlights were first invented more than 100 years ago, the batteries that powered them were weak and the light lasted for very short periods of time.When turned off, the chemistry in the cells rejuvenated, and the batteries recovered a portion of their power. Then they were ready to flash again. Sounds puny, but considering that the height of portable lighting technology up to that point was a flaming torch, this was a real technological breakthrough. Thankfully, mobile power has come a long way since then.

Modern batteries are capable of supplying power to electronic devices for extended periods of time. Like most other electronic components, some batteries are better suited for a particular task than others. Digital cameras and camcorders have specific battery requirements, but often we still have options.

One-Time-Use Batteries
All batteries fall into two general categories: one-time use and rechargeable. Let's look at the first category. Although marketing departments prefer to refer to them as "one-time use," it's environmentally safe to discard them in small quantities with household waste, so it's okay to call them "disposable." There are three important things to remember: Never mix old and new cells in the same device, as it can create a situation that promotes battery leakage; never dispose of them in a fire; and never attempt to recharge any cell unless it's clearly labeled "rechargeable."

Where digital cameras are concerned, the most common disposable batteries are the cylindrical 1.5-volt AA "penlight" type. Cells of this size got a bad rap in the early days of digital photography because alkaline AAs couldn't deliver enough power for a long enough period of time. Alkalines still lag behind in performance, but developments in battery chemistry have led to the creation of new generations of AA cells with greatly improved characteristics.

One of the most promising new chemical formulations is found in the Oxyride battery, which was developed by Matsushita for Panasonic. The oxy nickel hydroxide battery uses smaller chemical particles and a new manufacturing process to pack the particles closer together. The result is a higher-density energy cell that delivers anywhere from 1.5 to two times as much power as a standard alkaline. Despite their superior performance, these batteries are priced close to their less-gifted cousins, and typically cost only pennies more than conventional alkaline. Best of all, they're available from many national retailers. Expect to pay a bit more than a dollar per cell.

In the Energizer camp, we find the e2 Lithium, a high-performance AA battery that employs an altogether different chemical formulation. Energizer claims its e2 Lithium AA batteries can take up to 600 pictures under the same conditions, whereas an ordinary alkaline battery from a leading manufacturer can take only 90 pictures. Although results may vary depending on the camera, in actual field tests, the e2 Lithium delivered results that make these claims easy to believe. Also, the e2 Lithium cells boast a 15-year shelf life and weigh one-third less than standard alkaline batteries. You'll pay a premium price for this premium battery, but if it's to be deployed in a digital camera, MP3 player or similar high-drain application, you'll quickly recoup the cost difference. If your digital camera uses AA cells, it's wise to toss a couple packages of e2 Lithium cells in your gadget bag when you travel. Even if you normally use rechargeables, the day will come when you're glad to have this high-capacity alternative at hand.

Rechargeable Batteries

For rechargeable AA batteries, nickel metal hydride (NiMH) is the most common chemistry type. NiMH batteries are memory-free, environmentally green (i.e., landfill-friendly) and can survive up to 500 or more charges before suffering a chemical breakdown. Best of all, they're affordable, often costing less that $3 per cell. When you amortize the cost of rechargeable NiMH batteries and charger over 500 recharge cycles, they become ridiculously inexpensive.

For example, Maha Energy offers a set of four PowerEx 2500mAh cells for $13. Its MH-C204W One Hour Worldwide Travel Conditioning Charger ($30) weighs only four ounces and performs complete battery-reconditioning functions. Duracell, Energizer, Panasonic, Kodak and many other high-profile manufacturers also offer rechargeable NiMH batteries in AA, AAA, 9V and other sizes. It's a buyer's market, and as long as you stick to a major brand, you'll do okay. Just keep in mind that the milliamp hour rating (mAh) is the key to how long you can expect to continue taking pictures. Don't buy anything rated lower than 2300mAh. Read more.



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