Up until now, however, rechargeables haven't been a perfect solution for gadget users on the go. One of the most irritating things about rechargeable batteries is that they aren't charged when you buy them in a store.
Because most rechargeable batteries lose 90 percent of their energy over a few months' time, you can't immediately use the batteries you purchase at retail, no matter how desperate your gizmos are for some juice. You must first power up the batteries for several hours in a charger.
Fortunately, a new technology is about to change that, and batteries that take advantage of the new technique are already showing up in shops.
The Battery That Won't Die on a Shelf
The rechargeables that hold their charge, and come to you almost fully powered from retail stores, include the UniRoss Hybrio (photo, left). Similar technology also powers competing brands, such as the Sanyo Eneloop and the Rayovac Hybrid.
I wish I could tell you that all these batteries share a snappy, memorable name in common. Unfortunately, the best the makers have been able to come up with so far is to call these things "hybrid NiMH." (NiMH stands for nickel metal hydride.) NiMH is the technology inside ordinary rechargeable batteries, the ones that self-discharge rather rapidly. The new moniker isn't sexy, but "hybrid" is the label we're stuck with using for now.
The last time I wrote about batteries was in my Executive Tech column of Jan. 17, 2006. The subject back then was whether Panasonic's new Oxyride batteries were superior to Energizer's Lithiums. I concluded that the Lithiums lasted longer, but since they cost more than the Oxyrides, using either brand in a digital camera would produce about the same number of pictures per dollar. Rather than buying these disposable batteries, however, I recommended that you get rechargeables instead.
The advent of hybrid rechargeables makes this more true than ever. Now that hybrids can hold most of their charge for years, many of the objections to using rechargeables fall apart. You still have to periodically recharge such batteries, of course. But rechargeables pay for themselves as early as your second or third charge, compared with buying disposables and throwing them away.
Testing the Hybrid Battery Claims
I received a sample of four Hybrio AA batteries during a press event at the Consumer Electronics Show last month in Las Vegas. I put the batteries into a portable CD player, and -- without charging the batteries first -- they worked fine. That's hardly a scientific test, however.
Fortunately, independent reviews of hybrid rechargeables are starting to appear. Michael Hains, a blogger who's been conducting tests of batteries for years, recently published one of the first head-to-head comparisons.
He found that a 2,100-milliamp Hybrio AA battery that had sat in a store for at least five months lasted for more than 2 hours and 18 minutes in a torture test. (The batteries would almost certainly last longer in real-world use.) "That is fantastic performance for a Ni-MH battery," Hains writes.
A Sanyo Eneloop, with a slightly smaller capacity of 2,000 milliamps, lasted almost as long as the Hybrio: 2:04 out of the box and 2:36 after several recharging cycles. (Hains hasn't yet published results of the Hybrio after recharging.)
Neither of the hybrids run as long as the best rechargeables in Hains's testing. The prize is held by Sanyo's own 2,500-milliamp conventional NiMH rechargeables. They've lasted as long as 5:21 after several cycles. These higher-capacity Sanyos, of course, suffer from the same fast self-discharging problem as all other ordinary NiMH batteries. You'll have to decide for yourself whether the hybrid advantages of instant usefulness and long life are worth it to you.
You Get What You Pay For
Hybrid rechargeables will take a while to shove ordinary NiMH batteries out of the market. The price of hybrids is noticeably higher, for one thing. A pack of four AA Hybrios has a street price of about $10 at the moment. Four of Sanyo's 2,500-milliamp conventional NiMH batteries are going for about $8.
As the hybrid technology becomes better understood and is manufactured in larger quantities, however, the older rechargeables will eventually disappear, I predict. Many people, even now, are willing to pay a little more for hybrids just to ensure that their digital cameras and other electronic devices will still have power, even after they've been left unused in a closet for a few months.